[amsat-bb] EsHail Microwave transponder satellite

[Žilvinas Atkočiūnas]

I see L/Ku band implementation here:
http://www.prutchi.com/2012/03/11/d-i-y-combined-l-band-23-cm-helical-feed-and-ku-0-4-db-lnbf-for-120-cm-dish/
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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