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Hi Graham I think that the addition will prove a
worthwhile improvement. Try and get the wires over 700mm apart as soon as
possible leaving the pole ....use a spreadder ?? stopping the wires at 20ft is
fine. I doubt whether there will be a significant deviation from
an omni-directional pattern.
It would be great if you could measure the capacity
and the resistance (Rrad+Rloss) of the aerial untuned before and
after the change.
Alan
G3NYK
----- Original Message -----
Sent: Tuesday, December 03, 2013 9:37
PM
Subject: Re: LF: Re: Inv L 'FAN' top
wires ?
Err NCD on that one Pete , the last
'refurbishment' of the pole , attracted evil spirits
...so at 2x 20 2 inch alloy scaffold poles , that's
as good as it get's !
73-G,
Sent: Tuesday, December 03, 2013 9:13 PM
Subject: Re: LF: Re: Inv L 'FAN' top wires ?
Hi Graham
Probably better to put your efforts into making it higher ?
73 es GL Pete M0FMT IO91UX
Hi Graham, this will increase the aerial capacity
by around 100 to 120pF provided the new wires are not over/close to lossy
foliage/buildings, as the new wires are only the same length as the current
wires you will see little increase in Rrad, BUT you will see a proportional
decrease in the loss resistance. So the aerial becomes more
efficient......this assumes a flat fan not a sloping one.
Approximately, doubling the antenna capacitance
halves the Rloss which is the component determining the antenna current
you can drive and hence the ERP.
Alan
G3NYK
-----
Original Message -----
Sent:
Tuesday, December 03, 2013 12:20 AM
Subject:
LF: Inv L 'FAN' top wires ?
Anyone tried this configuration ?
Changing single 40 ft top wire on
inv-L to a FAN
shape x3 40 Ft , spaced about 10 ft
at far end
TNx -G,
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