This concluding article of the FM Antenna Systems series summarizes much of the earlier information by showing how the various recommended system components can be combined to produce high-quality antenna systems tailored to specific situations.
This is done with the three-column chart appearing on the following pages. To use this chart, scan the Reception Situation column until you find the one that most closely matches your own. Then, look at the corresponding Antenna System column to see which components you will need.
The number in the corresponding Layout column indicates which of the 2 System Layout diagrams to follow in connecting the various components together.
The various factors considered in outlining the reception situations include whether the system is for FM only or TV/FM reception, the number of tuners and/or TV sets served, the local signal strength, the presence or absence of r.f. and/or multipath interference, and whether reception will be from one direction or several.
Single-direction, weak-signal reception situations are further broken down by climate to permit choosing the lowest loss twinlead usable under the circumstances. If a reception factor is not mentioned in a particular reception situation, it means that the recommended antenna system is the same either way.
For simplicity, only one each of the recommended components (antenna, transmission line, etc.) are listed in the Antenna Systems. For convenience in purchasing, the components selected for a particular Antenna System are from the same manufacturer whenever possible. However, any of the other models recommended in the previous articles can be substituted; let price and availability be your guide. For instance, the Jerrold QFM-9 antenna with STO-82 balun can be substituted in any system specifying the Winegard CH-6060. In fact, the Jerrold combination has the edge in interference situations because of its slightly narrower beamwidth. Similarly, any of the previously recommended spooled RG59 (or RG6) sized foil cables can be substituted for the more convenient (but more expensive) Winegard CX-series prefabricated cables.
Certain subjective decisions were made in regard to technical approach.
For instance, switches were selected for "single FM tuner/single TV set" antenna systems in weak-signal areas instead of band separators (and their performance problems). Spooled coaxial cable is specified for the antenna cable in multiple-set systems instead of prefabricated cable because many pieces of different lengths are also required for the distribution system. Be sure to purchase a dozen or so F connectors when using spooled cable.
Reliable antenna rotators are available from Alliance, Cornell-Dubilier, Channel Master, Radio Shack, Antenna Corp. of America, and others. Most of these manufacturers offer a choice of either automatic or semiautomatic control units. Automatic rotators are most convenient when you know the bearing of the desired FM station; simply turn the knob to the desired bearing and the antenna will rotate to point itself in that direction. If you like to "hunt" new stations, the semiautomatic is preferable. With this type the antenna rotates as long as you hold down a rotation button, and a pointer indicates the immediate direction.
You will notice that all of the Antenna Systems are designed for FM-only, VHF-TV/FM, or UHF/VHF/FM reception. Although the UHF/VHF/FM systems can be used in areas where only FM and UHF TV are receivable, it is quite silly to do so since most of the size, cost, and performance of an all band antenna is attributable to the VHF section. Far superior performance at less cost is obtainable by installing separate FM and UHF antenna systems. The separate antennas can be installed on the same mast and rotated together, or the upper one can be rotated and the lower one fixed.
Multiple Set Considerations.
I strongly recommend that all multiple tuner installations use directional couplers regardless of signal level to ensure no multipath-like problems from mis-termination. In strong signal areas (5-50 millivolts output from a medium-sized log periodic), directional couplers with 12to 20-dB tap attenuation should be used. In medium-signal areas (2-5 millivolts), 6 to 9-dB directional couplers (RMS Electronics CA-1090 and CA-2012S series) are indicated. The style (1-tap, 2-tap, or 4-tap) of directional coupler(s) used in a multiple-set installation cannot be specified because it depends not only on the number of sets served, but also on the layout of the building in which the system is installed. The factors discussed in Part II must be considered in designing your system.
For simplicity in the multiple-set System Layout diagrams, only two sets are shown being served by the trunk line. In practice, additional directional couplers can be connected into the line to serve more sets (FM tuners and/or TV receivers), or multiple-tap directional couplers can be substituted for the single-tap couplers shown.
The only way to achieve multiple set operation in a weak-signal area is to use a low-noise distribution amplifier (good) or a mast-mounted preamp (best) to minimize the degradation in perceived S/N ratio that results from dividing a weak signal among many sets. However, this can only be done if all the signals in the passband of the amplifier (including local interference) are weak. Unlike FM tuners and TV sets, broadband amplifiers have no selectivity before their active devices, so even the finest are more susceptible to cross modulation.
When selecting an amplifier for TV/FM systems, be sure it has either no FM trap at all, or one that can be switched out of the circuit. Also, select a unit with a very low noise figure (3-4 dB) to minimize the degradation in S/N ratio. All of the Winegard mast mounted preamps shown in the sample layouts provide at least 14 dB gain, have VHF/FM noise figures of about 3 dB (the lowest currently available in a broadband amplifier), and FM traps that can be switched out. The Winegard AC-9130 has very-high gain (24 dB) for extremely-weak signal VHF/FM reception. An AH-0100 housing is needed to use any of these Winegard AC-series preamps with Jerrold antennas (or any other antenna, for that matter, other than Winegard Chromstars). The low-cost, low noise (3.5 dB) Winegard GA-6700 can be used in a similar manner to operate a multiple FM tuner system in a weak-signal area.
The author reports finding additional substitutes in case you have difficulty in obtaining some components; the RCA 10G221 and Arista 900 band separators are high-performance substitutes for the Jerrold FSX1314. Similarly, Antenna Corp. of America's HDW-series of prefabricated cables is an exact substitute for the Winegard CX-series.
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[Reception Situation
A) Single FM tuner Very strong signal area Many-direction reception No interference or multipath Low cost and simple operation B) Single FM tuner Strong-signal area Many-direction reception C) Single FM tuner Strong-signal area Single-direction reception D) Single FM tuner Weak-signal area Many-direction reception E) Single FM tuner Weak-signal area Single-direction reception No interference or multipath Dry Climate F) Single FM tuner Weak-signal area Single-direction reception No interference or multipath Wet climate G) Single FM tuner Weak-signal area Single-direction reception Interference and/or multipath H) Single FM tuner/single U/V TV set Strong-signal area Many-direction reception I) Single FM tuner/single U/V TV set Strong-signal area Single-direction reception J) Single FM tuner/single U/V TV set Weak-signal area Many-direction reception K) Single FM tuner/single U/V TV set Weak-signal area Single-direction reception No interference or multipath Dry climate L) Single FM tuner/single U/V TV set Weak-signal area Single-direction reception No interference of multipath Wet climate M) Single FM tuner/single U/V TV set Weak-signal area Single-direction reception Interference or multipath present N) Multiple FM tuners Strong-signal area Many-direction reception O) Multiple FM tuners Strong-signal area Single-direction reception P) Multiple FM tuners Weak-signal area Many-direction reception Q) Multiple FM tuners Weak-signal area Single-direction reception No interference or multipath R) Multiple FM tuners Weak-signal area Single-direction reception Multipath and/or interference S) Multiple FM tuners and U/V TV sets Strong-signal area Many-direction reception T) Multiple FM tuners and U/V TV sets Strong-signal area Single-direction reception U) Multiple FM tuners and U/V TV sets Medium-signal area Many-direction reception V) Multiple FM tuners and U/V TV sets Medium-signal area Single-direction reception W) Multiple FM tuners and TV sets UHF/VHF/FM Weak-signal area Many-direction reception X) Multiple FM tuners and TV sets UHF/VHF/FM Weak-signal area Single-direction reception Y) Multiple FM tuners and TV sets VHF/FM Weak-signal area Many-direction reception Z) Multiple FM tuners and TV sets VHF/FM Weak-signal area Single-direction reception
]
[
Antenna System Channel Master 4403 antenna Belden 9090 twinlead Winegard CH-6060 antenna Winegard CX coax Antenna rotator Winegard CH-6060 antenna Belden 9090 twinlead Winegard CH-6065 antenna Winegard CX coax Antenna rotator Winegard CH-6065 antenna Belden 8275 twinlead Winegard CH-6065 antenna Belden 8290 twinlead Winegard CH-6065 antenna Belden 8290 twinlead Jerrold VU-932S antenna Jerrold STO-82 balun Jerrold CAC-59 coax Antenna rotator Jerrold DC-12 dir. couplers Jerrold FSX-1314 band sep.
Jerrold TR-75F terminator Jerrold VU-9325 antenna Belden 9090 twinlead Jerrold FS-1314-FM band sep.
Jerrold VU-934S antenna Jerrold STO-82 balun Jerrold CAC-6 coax Jerrold DCS switch Antenna rotator Jerrold FSX-1314 band sep.
Jerrold VU-934S antenna Belden 8275 twinlead Jerrold-Taco 873 switch Channel Master 0012 band sep.
Jerrold VU-934S antenna Belden 8290 twinlead Jerrold-Taco 873 switch Channel Master 0012 band sep.
Jerrold VU-934S antenna Belden 8290 twinlead Jerrold-Taco 873 switch Channel Master 0012 band sep.
Winegard CH-6060 antenna Winegard CL-2700 coax Antenna rotator RMS directional couplers RMS CA-1230 termination Winegard CH-6060 antenna Winegard CL-2700 coax RMS directional couplers RMS CA-1230 termination Winegard CH-6065 antenna Winegard CL-2700 coax Antenna rotator Winegard GA-6700 preamp RMS directional couplers RMS CA-1230 termination Winegard CH-6065 antenna Belden 8275 twinlead Winegard FM-340 preamp RMS CA-2500 balun Winegard CL-2700 coax RMS directional couplers RMS CA-1230 termination Winegard CH-6065 antenna Winegard GA-6700 preamp Winegard CL-2700 coax RMS directional couplers RMS CA-1230 termination Jerrold VU-932S antenna Jerrold STO-82 balun Jerrold CAC-59 coax Antenna rotator Jerrold directional couplers Jerrold FSX-1314 band seps.
Jerrold TR-75F termination
Jerrold VU-932S antenna Jerrold STO-82 balun Jerrold CAC-59 coax Jerrold directional couplers Jerrold FSX-1314 band seps.
Jerrold TR-75F termination Jerrold VU-9345 antenna Jerrold STO-82 balun Jerrold CAC-6 coax Antenna rotator Jerrold directional couplers Jerrold FSX-1314 band seps.
Jerrold TR-75F termination Jerrold VU-934S antenna Jerrold STO-82 balun Jerrold CAC-6 coax Jerrold directional couplers Jerrold FSX-1314 band seps.
Jerrold TR-75F termination Jerrold VU-934S antenna Winegard AC-9880 preamp Winegard AH-0100 housing Winegard CL-2800 coax Antenna rotator Jerrold direction couplers Jerrold FSX-1314 band seps.
Jerrold VU-934S antenna Winegard AC-9880 preamp Winegard AH-0100 housing Winegard CL-2800 coax Jerrold directional couplers Jerrold FSX-1314 band seps.
Jerrold VU-9345 antenna Winegard AC-2950 preamp Winegard AH-0100 housing Winegard CL-2700 coax Antenna rotator RMS directional couplers RMS CA-2500 balun Jerrold VU-934S antenna Winegard AC-2950 preamp Winegard AH-0100 housing Winegard CL-2700 coax RMS directional couplers RMS CA-2500 balun
]
[Layout 2 2 3(Note 4)
3 3 4(N ote 1)
5
6(Note 1)
7(Notes 2,4)
7(Note 2)
7(Note 2)
8 8(Note 3)
9 9(Note 3)
9(Note3)
4(Note 1)
4(Note 1)
4(Note 1)
4(Note 1)
10 10(Note 3)
11 11(Note 3)
]
==========================
Installation Details.
Lightning protection must be provided for every antenna system. A four toot rod driven into the earth should be connected to the antenna mast by No. 8 aluminum wire. Additionally, a lightning arrestor (also connected to the earth) is required for systems using unshielded twinlead. Shielded twin lead and coaxial-cable must have their shields connected to earth ground.
Use high-quality 10-foot mast sections. Channel Master Duratube mast sections are the author's choice because of their high strength and exceptionally good rust-proofing. The Model 2012 is suitable for omnis, the 1812 for FM log-periodics, and the 1612 for large TV/FM antennas. Finally, make sure the mast is securely mounted.
Follow the directions accompanying the mounts you select, and don't make any compromises in their attachment.
Manufacturer's Directory:
If you cannot locate the desired device at your local electronics store, write to manufacturer at the address listed below for ordering information.
Alliance Mfg. Co. Channel Master Alliance, Ohio 44601; Ellenvillie, NY 12428
Antenna Corp. of America Box 865 Burlington, Iowa 52601
Belden Corp. Box 1331 Richmond, IN 47374
Cornell-Dubilier 150 Avenue L Newark, NJ 07105
Jerrold Electronics Box 487 Hatboro, PA 19040
RMS Electronics 50 Antin Place Bronx, NY 10462
Radio Shack One Tandy Center Ft. Worth, TX 76102
Winegard Co. 3000 Kirkwood St. Burlington, Iowa 52601
Layout Notes:
ii) For VHF/FM only, use Jerrold T-4000 baluns instead of FSX-1314 band separators.
2) For VHF/FM only, omit Channel Master 0012 band separator.
3) Omit antenna rotator
4) Ignore twinlead shield connection.
Also see:
- What Kind of FM Antenna is Best for You? (Part 1) (Jan. 1978)
- Antennas Part II--Transmission Lines & Signal Distribution (Feb. 1978)
- Antennas Part V -- Special Antenna Techniques (Jan. 1979)
(Source: Audio magazine, Apr. 1978; M. J. Salvati)
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