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It's hard to make too many generalizations about HTs and their antennas,
since the hand/body is such an important part of the system and it's so variable. But HT antennas still have to follow the rules like everything else, so we can get something of an idea of what a "tiger tail" does by knowing the rules. Remember that whatever current goes into the "antenna", an equal and opposite current (from the inside of the transmission line or connector) has to flow down over the rig, your hand, and body. (It comes out of the rig on the inside of the coax antenna connector shell.) Like any other current, this will split whenever it has more than one available path, and like any other current, the magnitude flowing each way is in inverse proportion to the impedance of that path. If a "tiger tail" is pretty close to resonance (not at all guaranteed by making it a quarter wavelength long, since it'll be influenced by nearby and touching objects), it'll represent a pretty low impedance. If it does, a good share of the total current will flow onto the "tiger tail" and less on you. It's likely, but not guaranteed, that the tiger tail's radiation will reinforce the "antenna"'s radiation better than the radiation from your body would -- although in some cases the body does act somewhat as a reflector. Also, the body is a lossy conductor, and I think that at 2 meters that would be true even considering the large area. So any current diverted to the relatively low loss "tiger tail" will at least contribute to radiation in some direction, rather than producing heat. The best portable antenna I've found for an HT is a base-matched half wave whip like the AEA "Hot Rod" or MFJ's copy of it, although it's unwieldy. The great advantage of this antenna is that the base current is very low, so the current flowing on your body is also very low and the antenna does most of the radiating. It's terribly difficult to do really good antenna measurements, but I was impressed with the effort put forth by Pierpoint and Brummer (KF4OW and W4RTZ) in doing their best to make objective measurements of some common HT antennas. Their results are certainly good enough to draw some general conclusions. You can see them in "An Investigation of 2-Meter HT Antenna Performance" in the _ARRL Antenna Compendium_, Vol. 4 (p. 198). Unfortunately, a "tiger tail" wasn't among their tested configurations. Roy Lewallen, W7EL Lee Hopper wrote: Roy Lewallen wrote: Finally, consider an HT... The other half of the antenna -- NOT a "counterpoise", but a real part of the antenna of at least equal importance to the intended part -- is the outside of the sleeve, and the outside of the HT, your hand, and your body... Roy & group: I have heard of holding a quarter-wavelength of wire next to the HT while transmitting. This has been called a "tiger tail" and is supposed to improve you radiated signal. http://adjunct.diodon349.com/Radio/ht_tiger_tails_and_other_good_info.htm Some attach this to the bnc at its base - others to the belt clip - still others just hold it beside the radio as they transmit. Do you think it might do any good? Lee H, NB7F |
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