Topband: "T" Antenna: EPILOGUE

[Edward Swynar]

Good Day All,

Many thanks to all who took the time to respond to my queries re. the "T" antenna, vs. the extended inverted "L" for 160-meters...

The general concensus is split about "50-50" in my musings about any advantage(s) in converting the existing extended "L" elements here in my array, to "T" elements.

I've looked back as far as HANDBOOKS from the 1930's for additional sage wisdom & tidbits from the ages, in the matter of specific "formulas", & guidelines for a "T": the west coast handbook from that era actually pictured TWO "top-loaded Marconis" in the chapter on antennas, i.e. the classic inverted "L" as we've come to know it to-day, and the "T"---but the "T" length was drawn-up as being 1/4-wave long, i.e. the length of the vertical portion, plus ONE HALF of the top tee...

To me, that would indicate two things, i.e.:

(1) The amount of wire in a "T" design like this actually EXCEEDS that required for an inverted "L" (by virtue of the amount of "extra" wire used in the SECOND half of the flat-top), and,

(2) The consequently larger flat-top / capacitive top would effectively LOWER the resonant frequency of the "T", as compared to an inverted "L" .

I'm thinking that what I might try to model on 10-meters---before tackling three such conversions on 160!---is to build a "T" with the overall length of TOTAL WIRE used in the antenna being equal to 1/4-wave (vs. just the vertical plus one half of the "T" added together equalling 1/4-wave, per the old Handbook). If I understand correctly, even a capacitive "hat" of that reduced size should effectively lower the resonant frequency of the system, thus allowing it to be tuned / tweaked by way of a series-installed variable capacitor at the base.

Interesting stuff, all this...thanks to all for indulging me on my "...personal path to knowledge & wisdom"...!

~73~ Eddy VE3CUI - VE3XZ

PS: I've just reviewed the final version of a write-up I submitted to The Radio Amateurs of Canada re. my 3-element phased array (160-meters), in its present configuration: they're going to include the piece in the antenna issue of The Canadian Amateur magazine this autumn...