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There is no issue with a horizontal small loop per se. In fact, if you want a horizontally polarized antenna with equal gain in the horizontal plane, a horizontal small loop is a great way to do it. A horizontally polarized dipole by comparison would have two nulls off the ends of the antenna. The nulls may or may not be useful for you. Nulls can be useful ...


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Another possible side effect is that a horizontal transmit loop antenna in the attic might couple more strongly into the house's AC wiring below it than a vertical loop or monopole. The house wiring might or might not distort the antenna's pattern much; but you may have to be more careful with regards to RFI getting into household appliances and electronics....


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A small horizontal loop will have two sharp nulls: one pointing straight up and one pointing straight down. That may: Help reduce losses in the soil directly beneath it Reduce the NVIS radiation directly overhead. On the lower bands, that could be a disadvantage if you want to work nearby stations, say, within a couple hundred miles. Lower the radiation ...


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If you mount it horizontally, it will be omnidirectional horizontally polarized. Because it loses its directionality, you also lose some of the gain, although this may not be all that significant.


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Although reciprocity and conjugate matching are physics facts there are certainly examples where an antenna system that is poorly matched will suffice for receive only use, ie on an HF band with high noise levels where the receiver is nowhere near it's limits of sensitivity and the receivers own noise levels are swamped by the received noise. Personally I ...


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In a coax-fed dipole, the coax core is connected to one element of the dipole and the braid to the other. At the rig, the coax core is connected to the hot end of its output and the braid to the chassis, which is the common or cold end. Incidentally, the chassis is connected to shack earth which is bonded to mains safety earth. This serves 2 purposes - as ...


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The optimal length for a HT whip antenna would be ¼ λ. The smaller rubber ducky, with its comparable performance, would win hands down for its convenience and ease of use. The performance of either would be enhanced by adding a ¼ λ flexible-wire counterpoise, popularly known as a 'rat tail' or 'tiger tail'. A ring-type lug, attached at one end of the ...


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You would need the following: Antenna - an inverted 'L' antenna using insulated wire strung between supports about 30' apart and 30' high. Earth - an underground metallic water pipe would make a good earth connection. Tuner - a parallel-tuned circuit (a coil with a variable capacitor across it) tuneable across the medium wave broadcast band. Detector - a ...


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RE: This antenna is showing only 30% radiation efficiency. What causes it to be so low? ... Is a radiation efficiency of only 30% the expected result for a radiator slightly less than half its ideal size? The value for the Radiat-eff. result in the 4nec2 display includes losses based on the amount of the originally-radiated r-f energy remaining after ...


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It depends on the type of the antenna. Mobile antennas are often monopoles. A monopole is self-resonant when it's a quarter wavelength long. A quarter wavelength is good: smaller, and the feedpoint impedance will be capacitave and may require a matching network. Matching networks introduce loss. larger, and the radiation pattern grows lobes that go up ...


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A quarter wavelength of coax (shortened by its velocity factor) is a notch filter if the far end is left open. So leave the far end open; and try feeding the coax from a frequency generator voltage source plus a series resistor at the near end; and sweep the frequency across a slightly wider range than is appropriate for an adjusted quarter wavelength to ...


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To answer the last part of the question, the detector for an AM receiver is basically a rectifier, which rectifies the RF and the signal that it was modulated with. Once the RF has been rectified, it has superimposed on it the original signal that the carrier was modulated with. This is then usually put through a low-pass filter to turn the "rectified RF ...


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The way I understand it, the tuner is an LC circuit forming a parallel tank that is designed to give maximum impedance at the desired frequency. This mean at that frequency, more current will flow through the detector and headphones than through the tank. At other frequencies, the tank circuit presents a low impedance and those signals are sent to ground ...


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The tuner is whatever allows the frequency to be selected. Tuners usually involve some kind of resonant circuit. For a very basic AM receiver like you describe, the tuner is probably nothing more than an LC circuit, with one or both of the inductor or capacitor being variable.


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To directly answer your question, the ideal antenna length for maximum radiation is dependent on the wavelength. For example, CB wavelength is approximately 11m. The ideal antenna is half of that for a dipole antenna. However, most CB (and HT) antennas are monopoles, which split the antenna in half and use its mount as the other half, so the ideal CB ...


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I had a 15" whip for my 2m HT that I thought performed quite well. Unfortunately I dropped my radio and that managed to snap the antenna. I have yet to replace it. You're gain isn't really proportional to the length. Rather, it's about the electrical resonance of that length. Think about humming an A really loudly next to a guitar. You can make the A string ...


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Typical HT antennas are very much a compromise. What would be considered a "basic" antenna at other bands would be a half-wave dipole, or a quarter-wave vertical with a ground plane or quarter-wave elevated radials. Polarization for FM is vertical, so a horizontal dipole won't work. Ordinary vertical dipoles are not very practical for portable use (the ...


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There are actually two types of helical antennas. The other answers talk about a directional helical antenna, also called an end fire helical antenna. However, there is also a broadside helical antenna, which is essentially a compromised (shortened) monopole. This antenna is omnidirectional. However, it is still not special (by itself at least) in ...


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If you are using a monopole antenna, when you hold the radio, your body acts as the image of the antenna to make a full dipole. This works for both transmit and receive. If you are receiving a strong signal, it doesn't make a lot of difference, but if you have a marginal signal, you will notice that it gets a lot worse if you set the radio down or put it ...


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The radiation efficiency of all antenna systems is the quotient of its radiation resistance and the sum of the real (energy-dissipating) resistive losses comprising that system. Some M-o-M software using NEC (Numerical Electromagnetics Code) reports values identified/expected to be radiation efficiency, but including the effects of propagation loss in those ...


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Ask the radio shop to show you the VSWR of the antennas at the frequencies you use. Have them do it in front of you. That will likely tell you whether the antennas are suitable or not. To ensure an accurate measurement, the antenna must be plugged directly into a VHF (not CB) SWR meter with no coaxial cable jumper between the antenna and the meter. A ...


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