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VK2ZZR > TECH 19.08.08 09:09l 68 Lines 1785 Bytes #999 (0) @ WW
BID : 302_YB8EW
Read: GUEST
Subj: Hello Tony and antenna builders
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>From: vk2zzr@yb8ew..#mkr.idn.oc
From: VK2ZZR@YB8EW..#MKR.IDN.OC
To : TECH@WW
7AX!VK2TGB!
From: VK2ZRG@VK2TGB.#SYD.NSW.AUS.OC
To : TECH@WW
VK2ZRG/TPK 1.83d Msg #:2220 Date:14-03-06 Time:23:53Z
Hello Tony and antenna builders,
I'm surprised that the small horn antenna worked better than your dish
antenna. A 91 cm dish has a gain of 24.8 dBi at 2.450 GHz.
> the results were super with 20db over a dipole possible.
If the aperture of the horn was 84mm diameter then it's gain couldn't
be more than 7 dBi. Is there something wrong with the dipole or your
measuring technique? Maybe the co-ax cable to the dipole is faulty.
If the co-ax connection to the dish isn't faulty then it looks like there
is something seriously wrong with your dish antenna. The dish surface would
have to be grossly deformed (i.e completely mangled) to reduce the gain to
below that of the horn, so that's probably not the problem. The maximum hole
size in the mesh for 2.45 GHz is 12mm or 1/2 inch. I suppose that's OK too.
If it's a home made dish then you would know where the focus should be.
Maybe it's a commercial dish designed for an offset feed and you have
the feed in the wrong place.
The other possibility is that the dish is working OK but it's pointed
in the wrong direction. A 91cm dish at 2.45 GHz has a 3 dB beamwidth of
9.4 degrees so must be carefully aimed to get maximum signal. The small
horn would have a fairly broad pattern, so wouldn't need precise aiming.
Good luck with your antenna building Tony.
73s from Ralph VK2ZRG@VK2WI.#SYD.NSW.AUS.OC
Taglines by Colin Coker G4FCN
C Program run, C Program Crash...ReWrite in Pascal!
[End of Message #643612 from VK2ZRG]
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