[Antennas] antenna trivia quiz for the day

2002年6月16日 18:21:26 -0500

Chad, I agree that almost anything metallic will radiate. But the rest of
your comments are inaccurate.
I use three antennas which are far out of resonance on any amateur band:
two 20-meter extended double zepps and a full-wave loop that happens to be
resonant about 4.5 MHz. Each of them will cover, and is used routinely on,
80 through 10 meters.
All are fed with ladder line and operate with high line SWR on most bands.
I use tuners on each line. There is no perceptible heat developed in any
tuner at the 100-watt power level.
Both theory and practice, including my own experience here, argue that
whether or not an antenna is resonant has little or nothing to do with its
efficiency as a radiator or the resulting efficiency of the impedance
matching network that make it a suitable load for a transmitter. 
In general, antenna tuners do not introduce excessive or usually even
noticeable loss into an antenna system. I have never seen an antenna tuner
for any power level that had a fan inside to get rid of the heat caused by
its losses. I have never felt any heat on the case of any antenna tuner
unless it was being used in an attempt to load 4 ft of wire on 160 for a
kilowatt! <:}
Sensible tuner applications are efficient and do not introduce excessive
loss, if any.
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
Chad~~KM5QF~~ wrote:
>> big enough capacitors u can load a doorknob to 160.
> any metallic object will radaite energy
> however, an impedance matching network no matter how complex
> will waste the vast majority of the signal as heat
> if the antenna in question is too far out of resonance.
>> and i concur with the dynamics of this question needing clarification