Section 15.219(b) Suggestions

Hello,

I hope this post is something cool to read?

Note: Intentional Radiator herein means as is mentioned in 15.219(c) a transmitter, and not to be confused with the antenna radiator.

Hello,

I hope this post is something cool to read?

Note: Intentional Radiator herein means as is mentioned in 15.219(c) a transmitter, and not to be confused with the antenna radiator.

The following is how I suggest new rules for Section 15.219(b) read. I have the specific explanations of the individual rules, and a useful software analysis design of the most efficient antenna that can possibly be made, from the vision of the antenna herein these suggestions. Drafted up in a main text with graphics for the analysis and data figures. Those things will be made available soon.

I believe that when the antenna design is published for your review you will like it. However the antennas envisioned below is not limited in these suggestions to a particular design or model. Only to physical height with certain guideline limitations on coil sizes (1 meter diameter coil max) and no limit on the coil length other than it can not exceed the 3 meter antenna height. Hence the entire antenna can also be a helical resonator (3 meters long only). Capacitance hats allowed. There will be some text data on the antenna design at the end of this text.

Remember that these are only rule suggestions and are not the official rules and are only submitted here for public review.

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Section 15.219 Operation in the band 510 – 1705 kHz.

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(a) The total input power to the final radio frequency stage (exclusive of filament or heater power) shall not exceed 100 milliwatts.

(the above wording is not effected by the following suggested rules)

…New rule suggestions begin now in section (b)…

(b) The total length of the transmission line, antenna and ground lead (if used) shall not exceed 3 meters. Wherein the 100 milliwatt transmitter does not comply with the following alternative antenna radiator rules below: otherwise, only use of an antenna radiator system as specified in this paragraph is allowed when the transmitter does not comply with the following specifications.

~ Those transmitters as defined above in 15.219 (a) who do not meet with the specifications of those things numbered below are subject to the specification of 15.219 (c). Whereas the following alternative application and Augmented Class of operation will conform to 15.219 (c) by reason of better devise specifications. These rules for an alternative antenna radiator system are for use only with a Part 15 unlicensed community station of 100 milliwatt as a small broadcast station only, and shall only apply to such a station and shall not be for use with any other Part 15 device of the “unintentional radiation types” and herein only applies to this section herein of 15.219. Where the 100 milliwatt type accepted transmitter utilizes the following specific technology features and operates in the Medium Wave “Regional Band” spectrum only as specified herein:

(1.) The type accepted transmitter for this class of use (as an Augmented Part 15 Intentional Radiator Class). Must have it’s signal generated by a crystal controlled oscillator, or a phase lock loop. Or by a digitally stabilized VFO, or a direct digital synthesizer (DDS) if the later is filtered. And hence must be stable; and well filtered if the signal generation method requires filtering. And can be either solid state and, or, vacuum tube technology. And hence can include a solid state/vacuum tube hybrid design.

(2.) The audio input bandwidth must be filtered down by 48 dB @ 20 kHz via a low pass audio filter after the audio peak limiting controlled stage.

(3.) The modulation peaks must be limited either by a automatic level control (alc) sampling circuit in the rf output, or a sampling control in the modulation stage, or audio compressor. And the sample must go back to control the level of the audio input stage before the audio bandwidth filter section. The filter must be after the controlled section. And the filtered output is used for the final stage modulation amplification or may directly go to the final amplifier. Performance of the filter is however best if placed before a last stage of modulation amplification where constant audio change of the circuit load is not as critical. The station in this section of 15.219 must not use an audio expander; only a compressor if that is the method of modulation peak limiting used.

(4.) The modulation must be capable of being monitored, via a modulation level meter. And the rf output should be monitored, however it is required that the swr ratio be monitored often, so that a condition of mismatch can be corrected. The station type accepted transmitter will have both a modulation meter and a swr meter either within the 100 milliwatt transmitter or external to it in the rf output transmission line.

(5.) The rf output to the antenna must pass through an acceptable low pass rf filter of at least 5 elements minimum (a double Pi network filter) with cutoff at -50 dB or more at or before 1780 kHz (and preferably if possible at 1750 kHz or below).

(6.) The feed point of the alternative antenna radiator herein must be fed with a LC matching network at the antenna feed point to prevent mismatch and possible coax cable outer shield radiation. And to offer another (medium) level of attenuation of in band and out of band spurious products.

(7.) The coax will be buried in the ground out to the radiator by a minimum depth of 12 inches. And may be of any length required “only” to reach the radiator. The coax on the antenna end shall not protrude more than 1 meter out of the ground to the feed point. Type accepted coax for use herein shall be a coax that utilizes 95% copper shield braid rated for underground use, or 100% foil shield with copper shield braid. (This coax specifications shall not apply to coax used in the leaky coax carrier current methods of Part 15.221 unlicensed stations.)

(8.) The antenna radiator for this alternative Augmented Class of Part 15.219 shall be made to resonate in the region of 1600 kHz to 1700 kHz. And made to resonate on the intended frequency of use.

(9.) The antenna radiator shall not exceed 3 meters in height above ground, and must have either a base loading coil, or a mid section loading coil or be made into a 3 meter length helical resonator (which would define the entire length of the antenna when formed into a helix). The base or midsection loading coil shall not exceed a diameter of (1 meter) 1000 mm wide. A 1 meter diameter capacitance hat may be used with the radiator. Of the toroid or flat aluminum disc types. And may be adjusted up to the radiator’s far end. Or down the main radiator upper rod length, to effect coil resonance if so required. The main radiator diameter must be 5 mm or greater for strength. The feed point at the base will be either an end feed arrangement or a coil tapped arrangement. The antenna shall not be mounted any place other than upon the ground, and may not be mounted up high on a mast or tower or upon a building. Exceeding the height limit is forbidden and having a unshielded (refer to (12) below) length of coax above ground, up mast or building is likewise forbidden.

(10.) An antenna base grounding wire must be used of no longer than 1 meter.

(11.) A ground wire will be used at the transmitter end to ground it so long as it is kept as short as possible. See the next rule for protecting the ground wire from emitting radiation.

(12.) If a length of coax going into the building must be longer than 5 foot going up the outside wall. A Faraday Cage made up of something such as poultry wire netting (chicken wire mesh fencing). Must be formed into a 1 foot diameter (minimum) cylinder of a length required to cover the length of exposed coax. And the coax situated in the very middle of it’s central length area within. Running up inside the middle of the cylinder of the cage. And the cage must be well grounded. And the ground wire to the transmitter shall go up inside the Faraday Cage likewise.

(13.) This alternative type of station, that operates at 100mW input to the antenna. Will only operate in the band spectrum of 1600 to 1700 kHz. And only on the existing channels spaced every 10 kHz apart, and not between channels. Since these small stations are local (small region) they will be authorized only for use in the Regional Band Segment. And, the station shall not operate on a frequency of, or adjacent to, a regional licensed station in the Medium Wave Service. A careful channel search of the area for many days, using as sensitive a broadcast receiver as possible, perhaps with a long wire for greater listening. This search should be done, so that the intended station will not operate on a frequency a occasional distant station can often be heard on. It is recommended that the FCC website be consulted as an aid in doing a search for stations in the users area. The search should go out as far as 250 miles radius as a good guide to the possible stations that might regularly be heard in the Augmented Class Section 15.219 unlicensed station’s region.

(14.) The station owner may build their own transmitter and use it if it meets with the above requirements. Kits and or fully assembled transmitters for this augmented 15.219(b) use. That have been certified by the FCC, must come with a complete technical servicing manual for the user. For servicing of the equipment themselves or via a qualified electronics technician in their area if they prefer the later.

(15.) 15.219 (a) transmitters that do not conform to the above Augmented Class of operation are to comply with the antenna radiator in the first paragraph of 15.219(b) and with 15.219(c) Each Augmented Class station in these rules are subject to inspection by the FCC if the FCC so desires. And if the station is not conforming to the standards herein it must abide by the request of the FCC as the FCC so chooses to impose upon the station. Or if the manufacture of equipment is not type accepted, or altering the equipment design after type acceptance, to conform otherwise as intended in these rules; shall be subject to the FCC’s Administrative actions.

(c) All emissions below 510 kHz or above 1705 kHz shall be attenuated at least 20 dB below the level of the un modulated carrier. Determination of compliance with the 20 dB attenuation specification may be based on measurements at the intentional radiator’s antenna output terminal unless the intentional radiator uses a permanently attached antenna, in which case compliance shall be demonstrated by
measuring the radiated emissions.

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Software Designed Antenna Analysis:

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For reference reasons. The following antenna design is based upon an excellent ground system resistance (R3) of 1 ohms across the feed point. The software used (R.J. Edwards vertiload.exe), analyzes a 1/4 electrical wavelength of vertical radiator wound up into a short loaded vertical of 3 meter height, resonate @ 1650 kHz. This happens to be the most efficient version of radiators that can be envisioned from the suggest radiator height rules. The coil is located 2/3rds up the length of the radiator, which is the most efficient coil location. Where the coil diameter is limited to 1 meter which is the capacitance hat diameter limitation. Wherein this design, the coil diameter serves also as a capacitance. The analyzed efficiency = 15.79% @ 1 ohms for the ground system resistance . As will be seen, this radiator model will be the standard model to reference other similar height models to. This is approximately 13% more efficient than the SSTRAN antenna plan designs which in software reaches only around 3.3% fundamental energy efficiency as the based loaded coil design. Though the SSTRAN antenna design is much more efficient than the vision of the current radiator in 15.219(b) as it is on the books now.

The following antenna is end fed at the bottom with a LC matching network.

“No capacitance hat is used with this radiator.”

Where feed point = R1 + R2 + R3

R1 = radiator ohmic resistance
R2 = radiation resistance
R3 = ground system resistance (1 ohm)

resonant frequency = 1.650 MHz
mast length = 1.873 meters @ 20 mm dia (fed at the bottom)
coil length = 0.25 meter
coil dia = 1 meter
length of coil wire = 48.8 meters
coil wire diameter = 12 mm (tubing)
space between coil turns = 7.2308 mm
top rod length = 0.874 meters @ 20 mm dia
overall radiator height = 2.997 meters

total electrical wire length (meters):
= 1.873m mast radiator + 48.8m coil + 0.874m top rod radiator
approx = to 1/4 wavelength

R1 radiator resistance loss = 0.39 ohms
R2 radiation resistance = 0.26 ohms
R3 earth loss = 1.0 ohm
feed point = 1.65 ohms

efficiency = 15.79%

15.79% of 100mW = 15.79mW radiated rf energy emission
(from this most efficient software design)

It then should be noted that since the coil diameter is limited to 1 meter diameter in these suggested rules. The efficiency at best is 15.79% if can be accomplished at all in a real example of this radiator as compared to this virtual model. ~ Where the ground system resistance is 1 ohm. ……It is possible that a few rare stations, may build a ground system that will result in R3 being less than 1 ohm. This however as mentioned elsewhere, will be rare out in the field in use.

Note: increasing the diameter of the coil will increase the efficiency slightly more but, incrementally and the matter starts to become tiresome and time consuming. And there needs to be a limit to which the design must conform to for good reasons. To limit the emissions to within reasonable levels. Hence the coil diameter is specified with a maximum limit of 1 meter.

Daniel Jackson 2007