[amsat-bb] EsHail Microwave transponder satellite

Žilvinas Atkočiūnas zilvinas.atkociunas at gmail.com
Fri Jun 3 08:18:49 UTC 2016

I see L/Ku band implementation here:
I wonder if this technique could be still valid for S band... I'm afraid
that helix will be to small to fit LNB ?

73 Zilvis LY2SS

2016-06-02 11:53 GMT+03:00 Edward R Cole <kl7uw at acsalaska.net>:

> Dual-band feed arrangements have been done on dishes used for eme.  A
> classic is 432/1296 feed of VK3UM or similar arrangement 432/2304: crossed
> dipole feed on 432 with cyl 1296 horn in the center of a large circular
> reflector plane.  But higher in mw wg horn feeds are normal.  Hard to get
> two horns in the same spot (focus).
> However, I have a cylindrical wg horn made by W1GHZ which feeds 24-GHz via
> wg into a smaller diameter wg section opening into a larger section which
> is fed 10-GHz via wg coax probe.  But this is not designed for dual-band
> duplex operation.
> At NASA duplex operation was accomplished using wg diplexers which cut-off
> RF at a higher frequency thru phasing techniques.  2.115-GHz Tx/2.295-GHz
> Rx.
> Another famous NASA operation used something called a dichroic plate.  The
> plate was put across the mouth of a feehorn so that only 8.4 GHz signals
> would penetrate the fine holes in the plate but reflect 2.2 GHz.  The Plate
> was angled to reflect the lower frequency to another horn positioned to
> look at the plate.  Of course the dish was 64m in diameter so the
> subreflector did not have to be small (about 3m to memory).  That was used
> in 1974 for an experiment on MA-10 encounter at Venus.
> I believe the 5G/10G sats are being designed with a 1m ground dish as
> standard.  1m offset dishes are common to the current Direct-TV/Dish Net
> market.  Here in AK 1m to 1.2m dish is std on houses (I have a 1.2m).  I
> also have our old Dish-Net dish which is 1.8m sitting on a pole with
> nothing hooked up.
> Unfortunately, ExHail will not be above horizon in Alaska.
> 73, Ed - KL7UW
> http://www.kl7uw.com
>     "Kits made by KL7UW"
> Dubus Mag business:
>     dubususa at gmail.com
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