I've had good results on CW using a 80/160 trapped inverted vees made with a
pair of Unadilla/Reyco traps.
73, Dick WC1M
-----Original Message-----
From: Mike Fatchett W0MU [mailto:w0mu@w0mu.com]
Sent: Wednesday, April 20, 2011 2:26 PM
To: towertalk@contesting.com
Subject: Re: [TowerTalk] Inverted V for 160/80 on the same feedline
In theory then you should be able to get a decent swr for both bands. I
don't really care about the bandwidth too much as they will be used for
CW in a contest.
The goal is to have a good match and a single feedline for weight,time,
baggage considerations for travel.
W0MU
On 4/20/2011 12:20 PM, Jim Brown wrote:
> On 4/20/2011 10:53 AM, Mike Fatchett W0MU wrote:
>> This might also be called a Fan dipole.
>>
>> Can you run 160 and 80 on the same feedline with decent swr? I have
>> tried to model this and have not been very successful.
>>
> The short answer is yes, sort-of. In general, the longer antenna will
> show the same SWR bandwdith as it would without the higher one, and the
> higher one will have it's SWR bandwidth reduced by about half. My
> experience is with 80/40 fans, and with 20/15/10 fans, and these
> characteristics show up both in the NEC models and in measurements of
> real antennas.
>
> This is exactly the opposite of what happens with the loaded multi-band
> dipoles like those sold by Hy Power Antenna Company -- the higher band
> antenna retains full SWR bandwidth, and the lower frequency (loaded)
> band has reduced SWR bandwidth. I've also modeled those antennas, and
> like them a lot. In boht cases, the reduced SWR bandwidth can be
> compensated with a tuner and losses minimized by using low loss feedlines.
>
> For more detail, see my applications notes on Antennas for Limited
> Space. There are two that compliment each other -- one is text, the
> other a power point presentation.
>
> http://audiosystemsgroup.com/publish.htm
>
> 73, Jim K9YC
>
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