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Inverted “V” My understanding is that the best or common angle is 90 degrees. The ARRL antenna book says 90 but nothing else. I found a web sight by K7MEM and in this web sight says “ For best results with this type of antenna, the Apex Angle should be kept between 70 and 110 Degrees. Below 70 Degrees the radiators start to become parallel to each other and signal canceling will start to occur. Above 110 Degrees the antenna starts looking like a standard dipole, minimizing any of the feed impedance and shortening effects. The optimum Apex Angle is 90 Degrees.” Thank you Martin E. Meserve K7MEM. My backyard is 61.5’ long if I install a 50’ tower add 3’ and have my 12’ end supports 60’ apart I’m looking at a inverted “V” apex angle of 72 degrees, close to the 70 degrees that Marten is talking about. In W1ICP Lew McCoys book he says basically throw up as long a wire as you can ad feed is with ladder line in the center and that is what I am going to do. I will be using the Palstar AT1KBAL tuner and W7FG 600-Ohm Open Wire Feeder But to put a proper base and a free standing tower up is a lot of money. And I’m looking for some more input on the 72 degree apex “V” angle. Am I going to be ok at 72? Do any of you hams put up such a narrow “V” up and had good results with it? Thank you KD7KCP C5641E@msn.com |
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Hello and welcome to Elmer Shack. Over a 46-year span in Two-Way RF Communication Electronics, both as a profession and as a hobby, I have built hundreds of Mono Band Hertz Center Fed (MBHCF) antennas, commonly called a Center Fed Dipole antenna, mounted in Inverted - 'V' configurations for both Military Tactical Field Radio Operations, as well as for mine and other Amateur Radio Service Licensed Stations. From many installation experiences the individual antenna legs can be positioned left and right of the center Balun or insulating support in any configuration as long as the apex angle is approximately less than 160 degrees and no less than 90 degrees. I also found that the most convenient height above ground for the apex angle is between 30 and 40 feet above ground. The leg ends were connected to end insulators and tied off at either ground level or up to an 8-foot level. With this type of configuration the antennas have worked extremely well. The ends of the MBHCF Inverted – ‘V’ configuration can be arranged as follows;
Another Inverted - 'V' configuration that works very well and you only need the same single support that you use for a Mono Band Hertz Center Fed (MBHCF) antenna, is an antenna array referred to as a Multiple Mono Band Hertz Center Fed Parallel Connected (MMBHCFPC) array, sometimes referred to as a "Center Fed Fan Dipole". In this configuration you can connect many MBHCF antennas to the single center Balun or insulating device. I personally use this configuration at my Amateur Radio Station and have six different pairs of legs covering the Amateur Radio Service Bands for 160 Meter Medium Frequency (MF) and 75/40/20/12/10 Meters High Frequency (HF). To have minimal headaches during installation, this type of array must be assembled starting with the highest frequency band number or lowest frequency that is desired to be operated on and adjust and prune the end lengths for the best impedance match between the antennas feedpoint impedance and the Coaxial Cable RF Transmission feedlines characteristic impedance. The frequency of the Alternating Current (AC) will take the legs with the least impedance, which means the legs cut for the electrical resonance at the frequency of the AC will appear as a low impedance and the other legs will appear as a high impedance. Once one pair of legs is resonant, attach the second pair of legs starting with the next band and adjust and prune it, then recheck the first pair of legs. Repeat this process until done. So if you want 160, 80, 40 and 20 Meters, start with 160 Meters first, then add 80 Meters, then 40 Meters and last add 20 Meters. All my leg ends were connected to end insulators and tied off at either ground level or up to an 8-foot level. With this configuration the antennas have worked extremely well and are assembled with only 1 support (mast), 1 Balun and 1 Coaxial Cable RF Transmission feed line versus 10 supports, 10 Baluns and 10 Coaxial Cable RF Transmission feed lines. The ends of the MMBHCF Inverted – ‘V’ configuration can be arranged as follows;
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