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Item 5.1 - Workshop on Amateur Radio Antenna Regulations,t OF POLY �Y City of Poway TyF roq ��¢� COUNCIL AGENDA REPORT C,I IN THE CO DATE: February 18, 2014 APPROVED APPROVED AS AMENDED ❑ (SEE MINUTES) DENIED ❑ REMOVED ❑ CONTINUED Resolution No. TO: Honorable Mayor and Members of the City Council FROM: Tina White, Interim City Manager (l, INITIATED BY: Robert J. Manis, Director of Development ServicesP4 Rich Whipple, City Planner Jason Martin, Senior Planner SUBJECT: Workshop on Amateur Radio Antenna Regulations Summary: On October 15, 2013, the City Council approved a staff work plan to evaluate potential regulations for amateur radio antennas that could be incorporated into the Poway Municipal Code (PMC). Since then, City staff has met with representatives from the local amateur radio community and other community members that are interested in the topic. The purpose of this workshop is to discuss the potential updated regulations. Recommended Action: It is recommended that the City Council direct staff to return to the City Council with an Ordinance amending the PMC with updated amateur radio antenna regulations. Background: The Federal Communications Commission (FCC) has regulatory and licensing oversight responsibility for amateur radio operators. California Government Code Section 65850.3 codifies in State law that the FCC has a limited pre - emption over local regulations governing amateur radio antenna facilities. FCC standards, however, do not fully pre -empt the City's ability to regulate amateur radio antennas under its local zoning authority. The degree to which a local jurisdiction can regulate under its zoning authority has been the subject of an FCC issued order ( "PRB -1 "), FCC issued clarifications of PRB -1, and numerous court cases. Ultimately, it has been concluded that a jurisdiction must make "reasonable accommodations" for amateur radio operators and installations. Amateur radio antennas, which are commonly referred to as "ham" radio antennas, are currently allowed in the City as accessory uses in all residential and commercial zones, as well as the Business Park, and are subject to the development standards and procedural requirements of Chapters 17.37 and 17.52 of the PMC. Additionally, amateur radio antennas are subject to the standards of the underlying zoning district in which they are located. A Minor Development Review Application (MDRA) is required to establish an amateur radio antenna that has a dimension greater than six feet in height or length. 1 of 30 February 18, 2014 Item # .7.1 Workshop on Amateur Radio Antenna Regulations February 18, 2014 Page 2 On December 6, 2005, City staff brought forward to the City Council a proposed PMC amendment to add/update regulations for amateur radio antennas. Staff had developed the PMC amendment in consultation with the City Attorney and with l input from representatives from the local amateur radio community. At the December 2005 public hearing, the City Council took no action on the proposed PMC amendment. On September 3, 2013, the City Council discussed the potential waiver of the MDRA processing fee for amateur radio antennas. The City Council acknowledged the benefits of amateur radios during emergencies when other forms of communication fail, and the assistance that the City and region receive in disaster preparedness. During the discussion on the MDRA fee waiver, a number of speakers raised the issue of regulations for amateur radio antennas. At the conclusion of the discussion; the City Council directed staff to prepare a Resolution amending the Master Fee Schedule to waive the MDRA fee for amateur radio antennas and directed staff to prepare a work plan to evaluate potential regulations for amateur radio antennas that would be in an amendment to the PMC. On October 15, 2013, the City Council approved a Resolution to waive the MDRA fee for amateur radio antennas and approved the workplan to evaluate regulations. Staff met with representatives from the local amateur radio community and with other community members that have expressed interest in the matter in January 2014. Findings: Current Regulations and Procedures Current regulations require that proposed amateur radio antennas that have a dimension greater than six feet in height or length be processed through a MDRA, with staff level approval. Through the MDRA process it is verified that the installation will comply with all applicable regulations, which include specific setback requirements from property lines and a 35 -foot maximum height limit. Additionally, through the process, staff works with the applicant to ensure that the installation is sited such that its visibility is limited to the maximum extent possible by placing the antenna behind existing structures or landscaping, or providing additional landscaping. The MDRA process includes a notice to adjacent property owners. It has been staff's experience that as a result of the noticing process, or after an approved facility is installed, nearby residents have expressed concerns regarding negative visual impacts to the neighborhood since the antennas cannot be fully screened. Representatives from the local amateur radio community and the City Attorney have indicated that the current regulations should be updated to comply with FCC standards. Regulations In Other Jurisdictions Staff has surveyed other jurisdictions in San Diego County regarding their regulations. The survey of other jurisdictions is included as Attachment A. Some of the jurisdictions surveyed have limited regulations regarding amateur radio antenna installation, others 2 of 30 February 18, 2014 Item # 5, Workshop on Amateur Radio Antenna Regulations February 18, 2014 Page 3 have more stringent regulations. For example, the cities of Carlsbad, Escondido, Vista, Encinitas, San Diego, and Chula Vista, and the County of San Diego, allow antennas with no specified height limit (or a relatively high limit of 100 feet or greater) without requiring any type of discretionary permit review. Others, such as Coronado, San Marcos, Santee, La Mesa, Oceanside, and Solana Beach, allow antennas up to a specified height (ranging from 15 feet to 66 feet, depending on the city) with no required discretionary review. For installations beyond the specified height limit in these cities, some type of discretionary review is required, but no maximum height limit is identified. The City of Del Mar requires discretionary permits for all antenna installations regardless of height, and has a height limit of 36 feet. Nearly all the surveyed jurisdictions do not allow installations in the required building setbacks of the subject zone, and do not have a limit on the number of antennas allowed on a site. Updated Regulations In updating/ adding amateur radio antenna regulations, the City is interested in input from not only the amateur radio community, but also other community members. Additionally, the City is interested in having the regulations necessary to preserve the visual qualities of the City, while still ensuring the reasonable accommodation of amateur radio operations. In meeting with representatives from the amateur radio community and other community members, staff used the draft PMC amendment from 2005 as a basis for discussion. The proposed 2005 PMC amendment would have allowed certain types of antennas with no discretionary permit review; others with an MDRA; and others with a Minor Conditional Use Permit. The proposed 2005 PMC amendment included the following: • Establishment of a category of exempt antennas that require no review or permit from the City, but are subject to placement requirements and are limited to three in number. The exempt antennas are characteristically slender, with a diameter of four inches or less, and are not supported by a structure (although guy wires may be used in some instances). Some of these vertical antennas could have slender horizontal antennas also. They are similar in appearance to roof - mounted television antennas. They would comply with the 35 -foot height limit, be outside of required setbacks for the zone, and be located on the site to minimize their appearance. A primary objective in developing the list of exempt antennas was to meet the needs of many amateur radio operators, and thereby create a situation where a typical operator would not have to go through any City discretionary process. • Require an MDRA for non - exempt antennas /support structures up to a height of 35 feet. • Clarify the development standards for these antennas /support structures. • Require a Minor Conditional Use Permit (MCUP) for antennas higher than 35 feet, up to 50 feet. The MCUP process would also allow an applicant to request an antenna/support structure higher than 50 feet, upon demonstration that the 3 of 30 February 18, 2014 Item # 5-, I Workshop on Amateur Radio Antenna Regulations February 18, 2014 Page 4 regulations prevent reception of a signal of acceptable quality and with special findings to be made by the City Council. At the January 2014 meeting with representatives from the local amateur radio community, which included their attorney, they indicated their belief that the 2005 proposed PMC amendment was too stringent and burdensome to amateur radio antenna operators. They questioned the fees for MDRAs and MCUPs. Prior to the City Council waiving of the MDRA fee for amateur radio antennas it was $719. The MCUP fee is currently $1,542, plus additional environmental fees which may be necessary based on the particular project. Additionally they questioned whether the regulations would be compliant with the FCC requirements and requested several modifications. They submitted a proposal for amendments to the PMC, which is included as Attachment B. In support of their proposal they submitted a technical analysis, which is included as Attachment C. The local amateur radio antenna community proposal includes the following: ® Distinguishing between the actual antenna and the antenna support structure as it pertains to height and setbacks. The antennas are typically long and slender, can be either vertically or horizontally oriented, are sometimes- comprised of an array or clustered, and sometimes will be adjusted to change the direction the antennas are pointing. The antennas are attached to a support structure which can be a simple pole or sometimes will be a more substantial lattice style tower. Sometimes the antenna support structure can be raised or lowered to change the height of the antennas. a Exempting antennas from any height limit and setback requirement regardless of the antenna support structure height or location. Requiring antenna support structures to comply with setback requirements of the applicable zone but the antennas themselves can project to the property line. • Allowing, without a MDRA, antenna support structures up to 65 feet in height. ® Allowing, with a MDRA, antenna support structures over 65 feet in height. o No limit on number of antennas. At the meeting with other community members, they acknowledged the need for the City to comply with the FCC requirements and indicated a general support for the regulations that were included in the proposed 2005 PMC amendment. They did agree, however, that the number limit on exempted antennas, which was three, be eliminated. They agreed that antenna support structures must comply with the setback requirement, but that the antennas could be allowed to encroach up to 20% into the side and /or rear yard setback. They also agreed that a roof mounted antenna/antenna support structure that is no more than 35 feet (combined total) in height measured from ground be allowed with no MDRA. 4 of 30 February 18, 2014 Item # 51 Workshop on Amateur Radio Antenna Regulations February 18, 2014 Page 5 The staff proposal includes revisions to the proposed 2005 PMC amendment that were made in response to the input received from the local amateur radio antenna community and other community members that met with staff. A summary of the City's existing regulations, the staff recommended regulations, the proposal by the representatives from the local amateur radio community, and the input from other community members are shown in the table included as Attachment D. City Council options include the following: 1. Direct staff to return to City Council with an Ordinance to amend the PMC with updated regulations, pursuant to the staff recommendations outlined in this report. 2. Direct staff to return to City Council with an Ordinance to amend the PMC with updated regulations with modifications discussed at this workshop. 3. Direct staff to discontinue work on this matter. Environmental Review The matter of this workshop discussion is not subject to the California Environmental Quality Act (CEQA). Any subsequent action by the City Council to amend the PMC would be subject to additional environmental review. Fiscal Impact: None. Public Notification: Notice of this Workshop was published in the Poway News Chieftain and sent to representatives from the local amateur radio antenna community and other community members that met with staff on this matter, individuals who have expressed interest in this matter to the City in writing, individuals that have spoken on this matter at past City Council meetings, and the current contact person for Home Owners Associations which are known to be active. Attachments: A. Survey of Regulations in Other Jurisdictions B. Proposal From the Local Amateur Radio Antenna Community C. Technical Report On Amateur Radio Antennas D. Summary of Existing Regulations, Staff Proposal, Local Amateur Radio Antenna Community Proposal, and Other Community Member Input Wplanning \14 Reports \Workshop\amateur radio \rpt.docx 5 of 30 February 18, 2014 Item # S, I Amateur Radio Antenna Standards in San Diego County 6 of 30 ATTACHMENT A February 18, 2014 Item # S.t Type of Discretionary City Permits He! ht Location Number Carlsbad None No Limit Not in required No limit building setbacks Coronado None for antennas up to 66 feet No Limit Not in required No limit in height, Special Use Permit for building over 66 feet setbacks Chula Vista None No limit No locational No limit requirements Del Mar Design Review Permit 26' ground, Subject to Design 36' roof Design Review Review Encinitas None for antennas up to 100 No Limit Not in required No limit feet in height, Major Use Permit front yard MUP if over 100 feet setback Escondido None No Limit Not in required No limit building setbacks La Mesa None for antennas up to 15 feet No Limit Not in required No limit in height, CUP for over 15 ft. front yard setback Lemon None for antennas up to 100 No Limit Not in required No limit Grove feet in height, CUP if over 100 front yard feet setback Oceanside None for freestanding antennas No Limit Not in required No limit up to 51 feet and roof- mounted building antennas up to 15 feet, CUP for setbacks over 51 feet freestanding /over 15 feet on roof - mounted San Diego None No limit Not in required No limit (City) building setbacks San Diego None for antennas up to 200 No limit Not in required No limit County feet in height, MUP for over 200 building feet setbacks San Marcos None for antennas up to 60 feet No Limit Not in required No limit in height, CUP for over 60 feet building setbacks Santee None for antennas up to 50 feet No Limit Not in required No limit in height, CUP for over 50 feet building setbacks Solana None for antennas to 40 feet in No Limit Not.in required One over Beach height, CUP if over 40 feet building 30 feet setbacks Vista None 100 feet Not in required No limit building setbacks 6 of 30 ATTACHMENT A February 18, 2014 Item # S.t ORDINANCE NO. AN ORDINANCE OF THE CITY OF POWAY, CALIFORNIA, CREATING CHAPTER _ OF THE POWAY MUNICIPAL CODE CONCERNING AMATEUR RADIO ANTENNAS (ZONING ORDINANCE AMENDMENT_--) WHEREAS, amateur (HAM) radio is recognized as a reliable emergency communication system, a valuable method of supporting international and regional goodwill, and a low - cost tool to encourage technology education and innovation by authorized amateur radio operators pursuant to 47 US Code of Federal Regulations Part 97; WHEREAS, the City Council prepared this Chapter in o1 to provide standards that are more specific to amateur radio antenna installations; a, WHEREAS, on 20_, the City Cou c1 eld§ a duly a Q Vertised public hearing to solicit comments from the public, both pro a.. . con, relative to this application. NOW, THEREFORE, THE CITY COUNCIL OF T t JTY OF `I3 WAY DOES 0 -' '� N AS FOLLOWS: Section 1: The City Council finds that the adopfir n of this Ordinance is exempt from the provisions of the California Environmental Qual't ct (CEQA), pursuant to Section 15061(b)(3) of the CEQA Guidelines,, because the Ordinance entails the update of existing regulations involving procedural chnges, and other de etopment standards that would allow amateur radio (HAM) antennas as limited ccesso I structures that would comply with height and setback requirements. A term s t a.t do not comply with the standards would be subject o fher discretion permit and environmental review. C. To reasonablyeaccommodate effective amateur radio communications, and to impose no unreasonable cost on the amateur radio operators. D. To provide the minimum practical regulation necessary to satisfy the aesthetic, health, safety and welfare concerns that have prompted these minimal restrictions on amateur radio antennas and their supporting structures. 7 of 30 ATTACHMENT B February 18, 2014 Item # S•( 17. .020 Amateur Radio Antennas Amateur radio antennas may be installed, erected and maintained within all zones in the City in accordance with the following provisions contained in this Section. A. Definitions. Whenever, in this Chapter, the following terms are used they shall have the meaning ascribed to them in this Section. 1. "Amateur radio antenna" means any antenna that is used for the purpose of transmitting and receiving radio signals in con).unction with an amateur radio station licensed by the Federal Communications Commission. "Antenna '9 -,1 2. Antenna structure means an amateur radio antenna s supporting mast or tower, if any. 3. "Reasonably effective radiac m unicatio.ns" refers to a ninety percent (90 %) minimum rate of successfu amat ur adio signal transmission and reception under the changing variab" "lest at impact such communications. B. Amateur radio antennas and ante na structures are a empt from the standard height limitations described for each zone in Title 17 of the Poway M n ^icipal Code and shall be subject solely to the provisions of this Chapter 17. C. Installation of an antenna structure up to height 65 `feet requires a building permit. An electrical permit sha;l also be req ' ed for anya tenna structure operating on 25 volts of power or more: D. Installation of an antenna Structure excee J, 5 feet in height, shall require approval of a minor develop t r vie. E. Develop ,1 e § t Standa - All antenn structure installations shall comply with the following unies, otherwise specified in this Chapter. 1. Permitted Heig 151r' e height of any antenna structure described in this Section shall be measured from the natural grade at the point the antenna structure touches, or if extended would touch, the ground. 2. Siting /Setbacks. An amateur radio antenna and /or an antenna structure shall bsconsidered to satisfy siting and setback criteria if: No portion of the amateur radio antenna or the antenna structure is permanently located within any required setback area. b. The amateur radio antenna and the antenna structure are located on the property to minimize its visibility from the street, while allowing reasonably effective radio communications from the installation. F. Application for Permit. When a minor development review permit is required, submittal 8 of 30 February 18, 2014 Item # S.I G H shall be on a form supplied by the Development Services Department and shall be accompanied by the following information, maps and plans: 1. A scale drawing showing the proposed location of the amateur radio antenna and antenna structure, if applicable, in relation to property lines. 2. Manufacturer's specifications of the amateur radio antenna and antenna structure, if applicable, including the wind loa AS the manufacturer's specifications are not available, applicant may alternatively provide the specifications in a report signed and stamped by a California licensed civil or structural engineer. 3. Elevations drawn to scale. Installations over 65 feet. The Director sha l grant a minor develop men review permit for an antenna structure over 65 eet in' , height upon 4 Ii i that: 1. The requested height of the insta I'ation i§ necessary to 4ccommodate reasonably effective radio communicaf 'on on the site; 2. The installation is located in such a mann " as to minimize visibility to the closest public street I wn possible, fam adj "scent property owners. Where screening is equ'rretl by the Director it may not substantially interfere with reasonably effective radio communications; and 3. There ire no other reaso ably feasib a alternatives. Alternatives which wo d su atantially increase the cost oinstallation shall not be considered reasonably easible alternatives. The appiicant s �find:inas can be r evidtnce necessary to document that the above �mpt AMINO , The fiol owing types of antennas shall be exempt from the permit uirements of this Section p {pvided all the conditions identified below are met: 1. Antennas legally established prior to the effective date of this Ordinance. Very gh Frequency (VHF) and Ultra High Frequency (UHF) antennas, whetter roof or ground mounted. 3. ,Vertical amateur radio antennas. Antennas of any type, whether roof or ground mounted, substantially projecting solely in the vertical plane. 4. Temporary antennas. Antennas of any type, whether supported, attached or otherwise affixed in, on or to a tree, wire, cord, or other non - permanent structure. Antennas which are regularly permanently affixed are not exempt under this Section. 9 of 30 February 18, 2014 Item # E. ( Amateur Radio Use. The use of amateur radio communications shall be deemed a permitted accessory use in all zones in the City. J. Binding Effect. This Ordinance shall apply throughout the City of Poway but shall in no way supersede any covenants, conditions, and restrictions relating to antenna placement or height on a given lot. EFFECTIVE DATE: This Ordinance shall take effect and be in fora thirty (30) days after the date of this passage; and before the expiration of fifteen (15 da s after its passage, it shall be published once with the names and members votin 'fo, and against the same in the Poway News Chieftain, a newspaper of general circuf do ublished in the City of Poway. Introduced and first read at a regular meeting of the C t ouncil of the Cit. of Poway held this day of 2014 and therea461 SSED AND ADOPTED at a regular meeting of said City Council held the d 20_, by the fo lowing roll call vote. AYES: ison, Mayor 10 of 30 February 18, 2014 Item # S. EFFECTIVE AMATEUR RADIO COMMUNICATIONS IN POWAY By Charles Ristorcelli, NN3V Executive Summary- This technical analysis identifies the minimum antenna height. needed for effective amateur radio communications in Poway, by analyzing the principal factors impacting long range radio communications. Effective communications are a 90% probability of achieving the desired communication. The analysis describes the components needed for a typical amateur radio station, identifies how environmental factors - influence radio propagation, and then studies the technical decisions and component selection for the radio station that lead to a compromise antenna height for a licensed amateur radio operator (Ham) to effectively communicate. The analysis is centered on a Poway Ham living on a standard lot size property, erecting at least a single permitted antenna, and desiring to operate the amateur radio station as a hobby, for experimentation, and as an. emergency communication service for Poway and San Diego County residents in event of a natural or man made disaster The uncontrollable laws of physics impacting the probability of achieving effective communications are examined and are considered that they "are what they are ". A radio station's elevation above sea level impacts long distance effective communication To study all possible radio location elevations in Poway, the analysis would. have to address - innumerable locations. Therefore, the analysis uses a 's eta. earth" a ptio -The impact of the assumption in effect lowers the analytical antenna height. This is considered a reasonable compromise. Antenna height is the core issue of concern surrounding the City of Poway proposed amateur radio antenna ordinance. This study .proves antenna height is the single most important controllable variable influencing effective communications at long distance, and technically specifies the needed compromise height. The analysis proves that the compromise antenna height needed for effective communication in Poway is 65 feet. 11 of 30 ATTACHMENT C February 18, 2014 Item # S.( Discussion "Effective radio communication" is achieved when there is a 90% probability of completing the communication. In the, aggregate of all possible factors influencing this situation, this is ultimately driven by four factors: the radiated power of the transmitting station antenna in the direction of the intended receiving antenna, the ionosphere, the receiver sensitivity, and the receiver selectivity The Electroma_grzetic Reciprocity Theorem states that the transmitted characteristics of an electromagnetic wave mirror those influencing its reception (Reference 1). This analysis concentrates on the transmitted signal and relies on reciprocity to apply the analysis to the received signal. The ionosphere is a region of the upper atmosphere lying between 55 miles and 370 miles above sea level. The ionosphere contains atoms and molecules that are highly charged by solar incidence and activity. The dominant influence on radio wave propagation is the ionosphere' -s condition. The ionosphere is not controllable; therefore the radio operator must be aware of its condition and choose a radio frequency suitable for the conditions and the target communication. The ionosphere reflects and refracts HF/VHF radio waves, permitting long range communication as illustrated in Figure 1. 2 12 of 30 February 18, 2014 Item # 5'• l Figure 1. - Radio signal propagation paths. Wrong Frequency Earth 'N As shown above, the ionosphere bends the transmitted wave directing it back to earth. Choosing the wrong frequency for a specific time of day and condition of the ionosphere does not bend the transmitted wave enough, so the signal escapes, as shown in Fig 1. With proper choices; the signal bends-back down, creating one or possibly many hops. Each hop covers a "skip distance " of about 2,500 miles. Multiple hops result in even greater communication range. The "critical angle " is the largest angle at which a radio wave of a specified frequency can be returned to Earth by the ionosphere. HF/VHF radio waves departing the antenna at or near tangent to the earth are more likely to provide the longest communication range. In the illustration in Figure 1, the signal that departs the transmitter tangent to the earth's surface is said to depart at "zero elevation ate. It travels the farthest to reach the ionosphere. Many other factors influence transmitted radio signals. Soil conductivity, moisture in the atmosphere, objects in the near and far fields of the propagation envelope, passing automobiles, lightning, etc. are not practically controllable by the operator. They too "are what they are" and must be tolerated. Topography influences propagation. While Poway presents innumerable hills and valleys, analyzing every possible location for a transmitter in Poway represents an insurmountable task. This analysis assumes a smooth earth surface. This is a routine assumption for propagation studies. For the objective of this study, this results in an acceptable compromise. 13 of 30 February 18, 2014 Item # S • ( Conditions at the radio station intended as the receiver "are what they are ". It is presumed the receiver operator has carried out a careful selection of components, and consequently maximized the receiver station sensitivity and selectivity. Operationally, the Poway Ham operator will use amateur radio for long range, ground based, terrestrial, point -to -point communication. The communication will be performed without assistance from other communications technologies i.e. intereet, telephony and relay points. The transmitter will be operated within its modulation and power limits. Living in the city, this operator will be situated permanently on a regular size city lot, and will design a modest cost amateur radio station. The steps in this analysis- consider the controllable environmental and operational factors influencing radio wave transmission. The Poway Ham must deal with these influences to achieve effective communications. Five fundamental factors must be considered to maximize any effective radio communications capability Antenna Type o Antenna installation height o Operating Radio Frequency e Maximum Effective Transmitted Power o Time of Day As a hobby or experimenter, the Poway Ham can choose any time to operate. However, we said there is interest in assuring the radio station is able to assist Poway residents with communications in the event of an emergency or disaster (major earthquake, fire, terrorist act, etc.). So the communication may have to be at any time (365 x 24 x 7), on the amateur radio bands most commonly used for communications within the United States, or to other countries. With limited residential property size, and considering practical and affordable amateur radio installations, this means operation on the 40 through 6 Meter amateur radio bands (HFNHF) using at least one permitted antenna. This is the most common amateur radio station configuration in the - world. Long range HFNHF communication is analogous to trying to illuminate an outdoor scene at night. You need the brightest possible light beam pointed only toward the scene, without illuminating objects outside the scene, or between the light and the scene. E 14 of 30 February 18, 2014 Item # S• l There are three things the Poway Ham can do to achieve effective communications: 1. Avoid terrain interference of the signal transmitted toward the receiver. This means avoiding hills, trees in the face of the antenna, large metal barns in front of the property, etc. 2. Maximize the station's effective transmitted signal power in the direction of the intended receiver. This is achieved by delivering the maximum possible transmitter power to the antenna, and ensuring the antenna can focus the transmitted power towards the intended receiver. 3. Minimize the departure angle of the transmitted signal radio wave toward the horizon. This is accomplished by ensuring the antenna is at the proper height above ground for the chosen operating frequency. The technical design, and operational decisions needed to-achieve the above are analyzed in detail in what follows. ANTENNA Points where "Impedance" must be matched RADIO TRANSMITTER - - - - - -= — COAXIAL CABLE Figure 1. - An amateur radio station Figure 1 is representative of a simple amateur radio station. To avoid propagation interference, the station should be at the highest point possible, devoid of hills, trees, and obstacles in the desired direction of propagation. For this analysis those factors are considered to be whatever they are, and we presume a smooth earth. The effect on the analysis at best is no impact, and at worst is to require 'a higher antenna installation. This is a reasonable compromise. 15 of 30 February 18, 2014 Item #5- Maximum radio signal power in the direction of an intended receiver is achieved by three conditions: ensuring that maximum power generated by the transmitter is transferred to the transmission line (wire) to the antenna; minimizing the loss of that power along the transmission line; and selecting an appropriate antenna for maximum directive gain towards the receiver. Power loss between the radio transmitter and antenna is minimized through proper transmitter design; transmission line choice; and minimum Standing Wave Ratio (SWR) on the transmission line. A standard, commercially available amateur radio transmitter manufactured to current technology standards is the basis of the analysis. The transmitter must transfer all of its power to the antenna. The key to this power transfer is the transmitter output impedance. All commonly available amateur radio transmitters and transceivers are manufactured with an output impedance of 50 ohms. The electromg netic maximum power transfer theorem shows that maximum power is transferred between a generator (transmitter) and a load (transmission line plus antenna) when the transmitter output impedance is equal to the load impedance. (Reference 2). In this case, the load impedance is the impedance seen by the transmitter at the transmission line input. This is a combination of the transmission line characteristic impedance plus the antenna impedance. Given the transmitter construction stated earlier, to transfer maximum power, the load impedance must be 50 ohms. There are many available choices for connecting a transmitter to an antenna. The conditions specified for this case narrow the selection. -A low visibility, easily installed, multi band capable transmission-line is needed. A coaxial transmission cable fills this need. Given that the transmitter output impedance is 50 ohms, the installation requires a 50 ohm coaxial cable. Two of the most common 50 ohm coax types are RG -58 and RG -8. Electromagnetic wave propagation along a coaxial cable will create what is known as a "standing wave " (Reference 3). The measure of the amount of standing wave present on a transmission line is known as the Standing Wave Ratio (SWR). SWR is a measure of the efficiency of power transfer, and is determined with a commercially and readily available instrument. While the effects of a standing wave on the operation of a transceiver and antenna are very complex, they can be best summarized by recognizing that the lower the SWR, the higher the transmitted power and the more effective communication. 16 of 30 February 18, 2014 Item # 5 , I Maximum power transfer to the antenna is achieved as shown in Reference 3 when the SWR on the line is 1 to 1 (a minimum). This takes place as predicted by the maximum power transfer theorem, when the coaxial cable characteristic impedance matches the load (in this case the antenna) impedance. The antenna needed must present 50 ohm input impedance. The antenna is the amateur radio station component with the greatest impact on effective communications, and antenna choices are truly innumerable. (Reference 4) For this case, the choices are conveniently limited by the operating constraints. The antenna must be multi -band capable, in the HFNHF range. Its characteristic impedance must match the transmission line impedance (50 ohms), and it must direct the transmitted signal toward the intended receiver. The most common and popular antenna in amateur radio is the 1/2 wave center -fed dipole (Reference 4). It consists of a wire parallel to the ground, split in the center where the, feed line from the transmitter is attached. The length of the wire is 1/2 the wavelength at the specifically transmitted frequency. An example is seen in Figure 2 Length (L) Figure 2. - Illustration of a 1/2 wave center fed dipole antenna While not capable of satisfying the operational need for multiband operation for the Poway Ham, it serves to illustrate important antenna properties. At resonance, as shown in the figure, the impedance presented by the antenna at the coax to the transmitter is 50 ohms. Again, by matching impedance, the antenna will accept all the power delivered by the transmitter to the coaxial feed line. Figure 3 shows the radiation pattern of a 1/2 wave center fed dipole antenna. This is a representation of the energy dispersed from the antenna suspended in free space. 7 17 of 30 February 18, 2014 Item # S. Signal energy Signal energy ran NIV Figure 3. Half wave center fed dipole radiation pattern in free space. (Reference 5) The transmitted signal energy leaves the antenna in a doughnut shaped pattern, with maximum power travelling at right angles to, and minimum power along, the antenna wire. Concentrating the signal power in a specific direction is what is known as "antenna directive gain ". Antenna directive gain is a measure of the power effectively transmitted by the antenna in the intended direction of transmission (Po), relative to the power delivered by the transmission line (Pi). It is measured in "decibels " abbreviated "db ". It is a logarithmic ratio of the output to the input power given by the formula: Gain = 10 log Po / Pi (Reference 4) If the directive gain of an antenna as given by the formula is 3 db, the radiated power from the antenna in the intended direction is twice the input power. Antenna gain is calculated in many ways. One way is to apply electromagnetic propagation theorems to antenna numerical models on the assumption they are in free space. This leads to the isotropic measure of gain, and is abbreviated dbi. The gain of a center fed i/2 wave dipole antenna is 2.15 dbi (Reference 4). Therefore the transmitted power in the maximum gain direction is 1.64 times greater than the power produced by the transmitter and delivered to the antenna. 8 18 of 30 February 18, 2014 Item # S. Without -the ground's influence, the '/2 wave dipole's radiation pattern is shaped like a pair of balloons (Figure 3, right). Proximity to the ground "squeezes the balloon ". As the balloon is squeezed, it collapses in some areas, and expands in others. The extent of the squeeze will vary with the height of the antenna over the ground (Reference 6). A half wave center fed dipole at %2 wavelength above ground has one lobe at 30 degrees. A half wave center fed dipole at, one wavelength above ground shows two lobes of radiation, one at 50 degrees elevation and the other at about 15 degrees. The ground effect is such that the higher the antenna is placed above ground, the closer the lowest lobe of radiation will be to the best departure angle for longest propagation distance. The effect is shown in Figure 4. Dspole, = -Wave High 0. dB -1 :") `M eve High 0 deg. Figure 4. - Pattern of radio signal energy transmitted into the ionosphere from two 1/2 wave center fed dipole antennas, each at a different suspension height above ground. (Reference 6) 19 of 30 February 18, 2014 Item # S.1 Analysis of all antennas reveals two important facts (Reference 6): 1. The departure angle at which a wave leaves the antenna is the key factor determining effective communication distances beyond line -of- sight: It is directly related to antenna height. The higher the antenna, the lower the departure angle, and the longer the resulting skip distance. For maximum long distance, the departure angle must be as low as possible. 2. In general, placing an amateur antenna system higher in the air enhances communication capabilities and also reduces electromagnetic interference with neighbors. Figure 1 illustrated the effect of the ionosphere on radio wave propagation. It showed that a radio wave leaving the antenna at the lowest departure angle is the one that propagates farthest. This is the effect the Poway Ham needs to achieve'. Figure 4 illustrates how a higher- antenna - produces a lower lobe. Consequently the higher an antenna is placed above ground, the- farther it will communicate because of the resulting lower radiation angle. Theoretical analysis, and millions of hours of communication operations show that a center fed '/z wave dipole antenna is not the most effective antenna for reliable 24x7x365 day multi -band communications. It is only resonant on one frequency band, creating high SWR values if operated at non - resonant frequencies, and -only provides modest gain in many directions, where a high gain in a single direction is needed. To transmit,a strong signal toward a chosen direction requires rotating the antenna. In the case of the center -fed %2 wave dipole, this requires antenna disassembly and repositioning, with all the attendant installation complications. Engineering research and design considerations have proven that multiple '/2 wave dipoles can be combined in various configurations to increase gain and directivity. The analogy of the balloon applies. The more dipoles, the greater the number of radiation pattern balloons, and the greater the squeezing effect of the ground. Obviously assembling multiple %2 wave center fed wire dipoles, of long lengths of wire, is very impractical. 10 20 of 30 February 18, 2014 Item # s. I This led to the design of what are called "directive beam antennas ". There are many commercially available for reasonable prices. They all offer increased gain, enhanced directivity, ease of erection and installation, and 50 ohm input impedance. One particularly well known type of beam antenna is called a Yagi, named after one of its Japanese inventors. The common television antenna is an example. Second to the Y2 wave center fed dipole, the yagi is the most popular amateur radio antenna (Reference 4). A 3 element yagi is illustrated in Figure 5. Figure 5. Three element yagi antenna consisting of the reflector element (far left), the feed element (middle), and the director element (far right) Depending on design, the yagi combines number of elements of varying lengths, separated by varying distances along a support boom. Electromagnetic design principles, too complex to describe here, allow multi -band operation (HFNHF) capability with an input impedance of 50 ohms. The antenna radiation patterns, vertical and horizontal, of a 4 element yagi antenna above ground are shown in Figure 6. The figure illustrates the directional gain achieved by a typical yagi antenna, in both the vertical and horizontal planes of radiation. �4. E _ Vertical Ili: Horizontal Figure 6. Yagi antenna radiation patterns. no D am 11 21 of 30 February 18, 2014 Item # 57•1 22 of 30 The construction of a yagi eliminates the disadvantages associated with' /2 wave center fed dipoles. Common commercially available yagi antennas are rugged, lightweight, and low profile. They can easily be rotated to aim their primary transmitted lobe in any direction. Their input impedance of 50 ohms meets our criteria for matched impedance and minimum SWR. In the IVNHF frequency range they produce horizontal polarization. Figure 7 shows a commercially available 4 element yagi antenna. f 1 J 1 ' Figure 7- Four element Yagi multi -band antenna designed to operate on the 40 — 6 meter amateur radio band. The second and third elements from the left are one continuous loop, and are the feed point for the antenna. 12 February 18, 2014 Item # S. I 23 of 30 Table 1 presents the performance specifications for the yagi shown in Figure 7. Performance for ]Licensed 'Bands 4E Gain 4>E ]Front to 30/40 Option 30/40 option Front to Rear, amateur radio operator gDlBn DBi ][dear, ➢Dl$ gain, lDBi DB 40M[ n/a n/a 1.8 n/a 30M[ n/a n/a 2.1 n/a 20M[ 9.5 21 17M[ 10 20 15M1 10.2 27 12M[ 10.4 21 10M[ 10.6 11 6M[ — 4 elements 7.8 4 Table 1. - Performance specifications of the yagi antenna shown in Figure 7. http://ww--,v.steppir.com/4-element-yagi The table shows that depending on the operating frequency, the antenna produces modest to substantial directive gain. In the case here illustrated for example, we find that: 1. In the 40 meter band, the antenna produces a gain of 1.8 dbi (1.5 times power gain) 2. In the 20 meter band, the antenna produces a gain of 9.5 dbi (8.9 times power gain) 3. In the 6 meter band, the antenna produces a gain of 7.8 dbi (6:0 times power gain) There are many other commercially available directional beam HFNHF multi band antennas besides the Yagi. Their application to an amateur radio station and the analysis of how their operation will satisfy the conditions we imposed for this analysis is the same as carried out above. The resulting hei ght for antenna installation is independent of antenna type, however different antennas will show variations in gain on some bands (depending on nature of the feed element or reflecting elements), the size of the boom on which the elements are attached, etc. Up to this point, the analysis has shown all the important technical decisions the Poway Ham must make in assembling an amateur radio station that delivers the requisite signal to a directive multi band antenna. 13 February 18, 2014 Item # 5.1 24 of 30 The final decision needed is a choice of the antenna support structure. The question is: Given the equipment selected, what is the minimum acceptable antenna heijeht for effective worldwide communications from Poway? As stated earlier, the best height must result in the lowest radiation departure angle, and that is frequency dependent. This poses a challenge. For the multi -band capability needed, different antenna heights are needed for each band. One might envision a structure that would raise and lower the antenna as a function of operating frequency. Such a structure would seem to be the commercially available "crank -up tower ". Unfortunately they are not built for that purpose. Instead they are intended to occasionally raise and lower the antenna for maintenance or experimentation Furthermore, any antenna selected for use as described would not survive the vibration stresses induced by the continued raising and lowering of the structure, and the apparatus used to raise and lower the antenna would have to be of special design to assure reliability. Neither is commercially available. So how can the necessary antenna height for 90% communications effectiveness on the HFNHF bands be decided? A compromise solution is to choose an antenna height optimized for the lowest departure angle at the highest HF frequency of operation. In this case that is the l Om meter band. The rationale for doing so will be explained in what follows. At the transmitting antenna, a detailed study of departure angles requires dealing with the effects of the "near field radiation pattern ". That is much too complex for this analysis. Fortunately, the near field effects disappear in the far field, where the receiving station is located. The earlier cited electromagnetic reciprocity theorem shows that the effects at the receiving antenna are identical to the effects at the transmitting antenna. Figure 8 shows a simplified view of the electromagnetic field effects at the receive antenna, "the far field ".. 14 February 18, 2014 Item # S• I Arrival angle, T ® o o ®v - T0 Dc Reflection point Standing A X W R wave Figure 8. Simplified depiction of incident (transmitted) electromagnetic energy arriving (departing) a receive (transmit) antenna. By analyzing the effect of the propagation path on the signal arriving at the receiving antenna, we get an understanding of the antenna height needed at the origin and reception antennas in order to achieve 90% communication effectiveness. The analysis must consider two electromagnetic waves. The wave arriving directly from reflecting off the ionosphere, and the wave bouncing from the earth's surface. Depending on the antenna height, the waves will arrive in or out of phase at various heights above ground, reinforcing or cancelling the resulting received signal. The effect creates a standing wave surrounding the antenna as illustrated by the sinusoidal pattern shown at the right of figure 8. Highest SWR (the humps to the right in the sinusoid) will vary in height depending on the frequency of operation. The antenna must not be placed at a height of maximum SWR, as that will minimize the received signal. The antenna installation height must also consider the radio wave arrival angles. The lower the angle of arrival, the longer the propagation from where the wave originated. The angles will also vary by operating frequency. Expected arrival angles for waves direct from the ionosphere for HF propagation are listed in Reference 8. They show that half the arrival angles are less than 6 °, and that 90% of the arrival angles are smaller than 16 °. 15 25 of 30 February 18, 2014 Item # 5.1 For multi -band HF signals, to achieve 90% probability of communication, the transmission and reception antennas must be at heights that exploit arrival angles up to 16 o. The Poway Ham must optimize the antenna height accordingly. The optimum heights to achieve minimum elevation angles for various frequency bands between 7 and 54 MHz are shown in Figure 9. The curves show four different minimum angles. The green curve shows optima for a V arrival angle, the red curve for 2 °, the blue curve for 3 °, and the black curve for 4 °. Increasing angles very scale somewhat with frequency, but not linearly. 80 60 50 40 30 20 10 Antenna height, 7 10 14 20 30 40 50 60 Frequency, MHz Figure 9 — Optimum antenna heights over even terrain for various frequencies. As shown above (Reference 7), to operate with the lowest possible arrival angle on the 10 meter band, the antenna height should be 19.9 Meters (65 feet). 10 Meters is the amateur radio band that, under satisfactory ionosphere conditions allows the longest range communications with the lowest necessary effective transmitted power (Reference 5). 16 26 of 30 February 18, 2014 Item # S. 32 in I `�.--- -- — — - — — — — - -. - -- ----- - - - - -- Best .Height I - Tmim.um — 15 m 1 deg 2 deg deg deg 7 10 14 20 30 40 50 60 Frequency, MHz Figure 9 — Optimum antenna heights over even terrain for various frequencies. As shown above (Reference 7), to operate with the lowest possible arrival angle on the 10 meter band, the antenna height should be 19.9 Meters (65 feet). 10 Meters is the amateur radio band that, under satisfactory ionosphere conditions allows the longest range communications with the lowest necessary effective transmitted power (Reference 5). 16 26 of 30 February 18, 2014 Item # S. Studying Figure 9 shows that as the operating band is lowered, the antenna height to achieve the lower angles rises. However, even when operating on the 20 meter band with an antenna height of 654 feet, an arrival angle of 4 degrees is achieved. That is an acceptable compromise, as other ionosphere factors compensate with multi -hop paths at the lower frequencies. The analysis does not ignore the lower 40 — 30 meter bands. While an antenna height of 65 feet leads to higher direct arrival angles (implying shorter propagation path), the utility of the bands for emergency communications are enhanced for medium range distances. Additionally, the utility of the lower bands during daylight for hobby operation is limited by the high ambient noise created by the ionosphere condition. Thus, with 65 ft antenna height, the Poway Ham achieves a station design that accomplishes, with a compromise to lower antenna height, a 90% probability of success for long range communications any time of day or night, regardless of the ionosphere condition. The Poway Hann should install the multi -band BF/VHF antenna at a compromise height of 65 feet. 17 27 of 30 February 18, 2014 Item # 5• I Reference 1. - Wikipedia. http:Hen.wikipedia.or- /wild /Reciprocity %28electromagnetism %o29 Reference 2. - Wikipedia http: / /en.,,viki edp ia.org /wiki /Maximum power transfer theorem Reference 3. ARRL Handbook For Radio Communications, Chapter 20, Section 20.1 Reference 4. - ARRL Handbook For Radio Communications, Chapter 21, Section 21.1 Reference 5. - ARRL Handbook For Radio Communications, Chapter 21, Section 21.2.1 Reference 6. - "Antenna Height and Communications Effectiveness ", Second Edition, by R. Dean Straw, N6BV, and Gerald A. Hall, K1 TV, Reference 7. - "An Optimum Height for an Elevated HFAntenna ", QEX May 2011, by Kazimierz "Kai" Siwiak, KE4PT Reference 8. - The ARRL Antenna Book, 18th. Edition, April 1997, Chapter 20. About the author. - Mr. Ristorcelli has been a Licensed amateur radio operator radio operator (NN3V) since 1976. A graduate engineer; he holds a B.S.E.E, M.S.E.E. and M.S.C.S, and the Degree Electrical Engineer (PhD, ABD) specializing in electromagnetic propagation and communication systems. During 35 years as a U.S. Navy officer he commanded ships, and was the Commanding Officer of Naval Electronics Systems Engineering Center, Portsmouth . Virginia, responsible for the procurement, installation, and maintenance of the Navy's worldwide communication system. During the last 8 years of Navy service as the Director of Navy Electronic Combat Surveillance Systems, he was responsible for the design, procurement, installation, and maintenance of the Navy's afloat and ashore HF/VHF/UHF surveillance network. 18 28 of 30 February 18, 2014 Item # 5.1 29 of 30 ATTACHMENT D February 18, 2014 Item # 5,/ LO cz c vi 0 o c L d = cz ° i C C O O c,= cz N - p O Q o tC C �' ++ a) Q C O Q a � 0 U , i a) 0- p O} � C c� U � � L E a) C } Q a) > C r O 0 O1 0'.- yL. p O O cc E C cz i) -c O O (� Y E CZ 70 -p. 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O Y E d O cz O a) C _ a) 00 O C Vg Uco C�cncocztn(0QacnCNUU) N CZ +' 0 cn E CZ _ cz -2 O O O (D i._ . cz N •Q + Q. � cz d vim N� Ea) o��M Ln to c O O d) 'Q -p U Q p CL 75 0- cn'Q �N a) " O`n N t CO N O O U U Q Q N E �� xQWacZ c�Q>' c- a) E �� a) xa- o00� w� E C (na) o Z o cn c CZ o CZ � a� = �� 3 � o .�c c Q � 0 <0 � ai CD a) cz Q N cz U)i'UZ cz0 Q 3 ONQ°n 0 o w��0� z O • • . . • 0 C C N Q a O a) E w U •x Di U ,_ O a) Q O C C U +. a) O O O Z H CZ U CO N Z Z C O cn cz Q C a E cz _ E Q O cn Q N X= O Z (f) w cz U U 30 of 30 February 18, 2014 Item # S, I