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LF: Re: Re: Antenna Diversity

To: <[email protected]>
Subject: LF: Re: Re: Antenna Diversity
From: "mal hamilton" <[email protected]>
Date: Tue, 13 Jan 2009 19:58:36 -0000
References: <003301c9759e$c21f3f00$0301a8c0@mal769a60aa920> <7665659012654DCE89B4DD1FC8228550@JimPC>
Reply-to: [email protected]
Sender: [email protected]

Yes Jim
I have all of this in mind, but I am not too concerned about the detail at present, just trying to observe the sig quality for qso purposes. I would like to try it some time on the TR path. The best method of course is one RX and both antennas fed to it via a mixer and each antenna input calibrated and equalised. Ideally each antenna should have a separation of 1 wavelength at least, but that is difficult considering the freq and space reqd.
I have seen this done on HF and it is vy impressive.
There are other ways if one had the time.
73 and tnx ur observations de mal/g3kev

----- Original Message ----- From: "James Moritz" <[email protected]>
To: <[email protected]>
Sent: Tuesday, January 13, 2009 6:37 PM
Subject: LF: Re: Antenna Diversity


Dear Mal, LF Group,

That is an interesting experiment - It would be interesting to know how far
apart the loops are to result in different fading patterns.

I would be very wary in interpreting the results from two totally different
types of receiver - The SLM has essentially a fixed gain, while I see the
IC-746 has a DSP "back end" with complex AGC loops acting on both analogue
and digital parts. I guess the AGC in the IC746 is never totally disabled in
order to prevent overloading of the A/D converter. So that may explain why
loop "B" has a more constant apparent output level. One check would be to
swap over the antennas between receivers, and see what difference that made. I suppose it would not be too difficult to have, say, a relay that switched
the same RX input between the two antennas, perhaps every 10 or 20s or so,
with an attenuator pad to get the signal levels roughly equal. That way ,
the comparison could be made with a single receiver.

Cheers, Jim Moritz
73 de M0BMU

----- Original Message ----- From: "mal hamilton" <[email protected]>
To: "rsgb" <[email protected]>
Sent: Tuesday, January 13, 2009 4:48 PM
Subject: LF: Antenna Diversity


LF/MF
I am experimenting at present with antenna (space diversity) using two
loops...




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