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Topic Title: Multiple Antenna connection help needed
Topic Summary: Connection of three HF antenna's without losses required
Created On: 23 May 2010 03:06 PM
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 23 May 2010 03:06 PM
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David Ashley

Posts: 11
Joined: 01 April 2006

Can anyone out there help me with an antenna connection problem please?

My task is to connect three antenna's together (one omni-directional & two directionals) so that a receiver can pick up a voice signal on any of them without any losses. It is to be usable in the HF band 3-30MHz and the receiver will be scanning through a scanset of around ten dedicated frequencies looking for a voice signal.

I have tested each antenna through the receiver and get good individual gain and quality but if I were to try to connect any two together using a passive coupler, the base noise level increases and the wanted signal strength decreases. With two connected I just have enough signal strength to pick it up, if I connect all three together, the signal is swamped out almost completely and is unusable.

I understand that there may be a problem with the change of phase input from all three cancelling the signal out but the base noise is also a problem.

Does anyone know of any proven method of completing my task so that I have good signal strength and quality over the frequency range coming in on any one of the three antenna's?

Please help!!!

Many thanks
David
 23 May 2010 04:42 PM
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David Ashley

Posts: 11
Joined: 01 April 2006

Alan,

Thanks for the quick reply.

The problem I have is that the Omni is already set up as a scan cct with the receiver and a scanset. I need to add the two directionals to this cct.

Scanning the antenna's will need to be done for each of the scanset frequencies (around ten) therefore needing 30 scans to the present 10. This would prove very difficult for me to integrate. But, thanks for the idea, keep them coming!!!

David
 25 May 2010 11:47 AM
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haguetim

Posts: 109
Joined: 25 April 2006

Hi

I don't really know of any `lossless' signal combining, you may need to have a pre-amp before the combining network, what type of combining are you trying?

Cheers

Tim Hague
www.uk-ar.co.uk
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