[Lowfer] Umbrella Antenna.

[Joe]

Hello Bill,

while it is true that the "parameter wire" you describe improves the efficiency of the umbrella antenna, an additional wire of the same length will do the job just as well.
This "parameter wire" increases the antenna capacitance (for horizontal wires by about 7 pF/m), so the inductance of the loading coil can be reduced to reach resonance.
This is the "gain", or better the reduction of losses by adding TopCaps.

73 Joe/DF2JP

ps. ps. It's nice to see some real life back here in the list with the start of the new season. ;o)




-----Ursprüngliche Nachricht-----
Von: lowfer-bounces at mailman.qth.net [mailto:lowfer-bounces at mailman.qth.net] Im Auftrag von William E. Isakson
Gesendet: Dienstag, 10. Oktober 2023 08:20
An: Discussion of the Lowfer (US, European, & UK) and MedFer bands
Betreff: Re: [Lowfer] Umbrella Antenna.

Kurt, that is just a top loaded vertical exactly like most of us were using during the time that the low bands were being tested before they were made
ham bands.   I am very surprised that you had not seen one before.   Most
of what is seen in your wikipedia article are lacking a perimeter wire, a
wire that connects all the top wires together around the perimeter.    A
perimeter wire adds very substantially to the effectiveness.     Also, when
you drape the wires down like those shown, there is quite a bit of
sheilding that goes on.   It is helpful to put the wire ends as high as
possible.
I should also note that Butternut sells a top loading set of wires to go
with its basic vertical for 160 meters.   It gives you a broader working
range.
--------

Bill Isakson
AC6QV
Oregon USA
bill.isakson at gmail.com