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Re: Stacked Lindenblads?



Hi Mike,

When a RHCP signal hits an object, the reflected
signal is LHCP. So, unlike a Yagi, a RHCP Lindenblad
set up for LEO use will work for both RHCP and LCHP
satellites because the LHCP signal that is reflected
off of the ground is RHCP. The difference between the
direct and reflected signals depends upon the characteristics
of your local ground but in general will be down at most
a few dB. You would likely not notice the difference.

On the other hand, if you stack a pair of RHCP Lindenblads,
spaced 1/2 wavelength and fed in-phase, you will get a
somewhat better pattern for DXing on LEO satellites (i.e. higher
gain at low elevation angles.)

I have used a pair of stacked RHCP Lindenblads in the past
this way and it worked very well.

On VHF, you probably won't need the preamp. The background
noise temperature with an omni antenna on 2m is so high, you
won't get much of a S/N improvement over any decent receiver
(assuming you use low-loss coax.)

73,
Tony AA2TX

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At 06:48 AM 4/30/2004 -0500, Michael Pfeuffer wrote:

>Hi All,
>
>Has anyone tried stacking Lindenblads for LEO use?  I've got in mind a 
>"Christmas tree" of 4 antennas ( RHCP & LHCP, 70cm & 2m).  Between each 
>pair of antennas is a preamp & rf relay for switching polarity.  I figure 
>as long as there's enough separation (>1/2 wavelength?) between the 
>antennas, there shouldn't be a problem.

----
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