[TowerTalk] Inverted V for 160/80 on the same feedline

[Dick Green WC1M]

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 at w0mu.com] 
Sent: Wednesday, April 20, 2011 2:26 PM
To: towertalk at 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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