[Antennas] TA32 Update - more puzzling than ever

[George, W5YR]

Splendid idea, Sean - didn't think of that one!

One caveat, though. While the resistive component of the antenna input Z
varies only slightly for minor frequency excursions around the resonant
frequency, the reactive component varies relatively rapidly and switches
sign as you go above and below resonance. So, I would suggest that John pay
careful attention to determining the resonant frequency of the antenna as
presently tuned as closely as possible and then cut the feedlines
accordingly. Then take pains to take data at that frequency.

With only a 22' 10" line on 20, that still puts his body and analyzer quite
close to the antenna. I would suggest that he use at least double that
length in order to get himself out of the near field as far as is
reasonable. If he is at least one wavelength (in space) away from the
antenna, his body should have no undue influence on the data. Since on 20 a
wavelength is about 67 ft, a much longer line would be likely to produce
more accurate data.

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


Sean Nolan wrote:
> 
> John
> In addition to what George W5YR wrote in his post I would also suggest that
> you make up two coax leads as follows 22feet 10 inches and 15 feet 4 inches
> with appropriate plugs on both ends.  Assuming a velocity factor of 0.66 for
> the cable the first lead would be a half wave at 14.2MHz and two half waves
> on 28.4MHz.  The second lead would be a half wave on 21.2MHz.  Using these
> on the tree bands to couple the analyser to the antenna would ensure that
> you are presenting to the analyser the feedpoint impedence of the antenna at
> these frequencies.
> At least it is worth a try.  Since you seem to be able to put the antenna up
> and take it down relatively easily I would put it in its position and check
> it through the half wave lines.  Good luck with it anyway
> 
> Sean EI7CD