[Antennas] W3EDP and mobile antennas

2002年5月18日 19:10:03 -0500

Joe, the short answer is that your tuner was transforming whatever
impedance the piece of the antenna was presenting at its terminals, as
transformed by the transmission line, to a 50 ohm resistive load for the
transmitter. If it was actually tuned so that it did indeed look like a 50
ohm resistor to the rig, then any power from the rig would be partly
radiated by the antenna fragment and the rest of the power would be
dissipated in the loss resistance of the tuner, coax, and antenna.
The kicker is that you probably had very little desireable radiation from
the antenna fragment. The fact that you made the antenna system appear to
the transmitter as an acceptable load says nothing about the radiation
capabilities of the antenna itself. "Tuning" an antenna system has little
relationship to how well the system radiates and acts as an antenna.
My comments are based upon my interpretation of what you are describing
when you say that you could "tune" the antenna and how that condition was
determined, etc. The old saying that "anything" will radiate if you can get
some power into it is still true - just that some"anythings" will radiate
better than others! <:}
-- 
73/72/oo, George W5YR - the Yellow Rose of Texas 
Fairview, TX 30 mi NE of Dallas in Collin county EM13qe 
Amateur Radio W5YR, in the 56th year and it just keeps getting better!
QRP-L 1373 NETXQRP 6 SOC 262 COG 8 FPQRP 404 TEN-X 11771 I-LINK 11735
Icom IC-756PRO #02121 Kachina 505 DSP #91900556 Icom IC-765 #02437
Joe Falcone wrote:
>> Regarding "gain": You do get gain in one or more directions but you would then lose in one or more directions. I realized with the "long wire" I could get gain in the direction that I was stringing the wire if I went long enough, (and losing it in other directions), but that was not the purpose of why I wanted a W3EDP antenna. I just wanted one that radiated more or less in all directions.
>> I imagine that there is a point where your antenna, if it is too short, will not be able to radiate all its energy, even if you use a tuner, and then you will experience a loss of power going out and a loss of signal coming in.
>> I once talked to the owner of the Lakeside antenna company. The one that makes those Hamstick antennas. I had hamsticks on my car and had a Yaesu radio with a built in tuner. I could tune the antenna with just hitting the button on the radio even without having the stainless steel whip on the antenna. The whip was one-half of the physical length of the antenna. I called the owner and asked him if the antenna would work just as well without the whip as long as I could get a match on my tuner. He said no, that it needed the whip. (He was very nice and said that everyone wanted a short mobile antenna and if he could make one that worked as well being short without the whip, he would.)
>> I still did not understand that if I could tune it why it was not working as well as if I had the whip on it. Could someone answer that? Thanks, Joe.