Hackaday via rec.radio.amateur.moderated Admin
2020-08-05 05:13:50 UTC
amateur radio - Hackaday
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A Hybrid Helical Antenna for the Eshail-2 Geosynchronous Repeater
Posted: 04 Aug 2020 07:00 PM PDT
https://hackaday.com/2020/08/04/a-hybrid-helical-antenna-for-the-eshail-2-geosynchronous-repeater/
Amateur radio operators like to say that working a contact in space can be
done with a simple handheld transceiver and a homemade antenna. And while
thats true, its true only for low Earth orbit satellites such as the ISS.
If you want to reach a satellite in geosynchronous orbit itll take a little
more effort, and this dual-feed helical ice cream cone antenna could really
help.
Until recently, the dream of an amateur radio repeater in geosynchronous
orbit remained out of reach, but that changed with the launch of the Qatari
satellite Eshail-2 last year. Since then, hams from Brazil to Thailand have
been using the repeater, and UK-based [Tech Minds] has been in the thick of
the action. The antenna he presents is a hybrid design, needed because of
the 2.4-GHz band uplink and 10-GHz downlink on the satellite, also known as
QO-100. Both require a largish dish antenna, with the downlink requiring a
low-noise block downconverter (LNB) and feed horn. The uplink side of [Tech
Minds] antenna is a helical design, with three-and-a-half turns of heavy
copper wire and a tuning section of copper strapping that attaches directly
to an N-type connector. The helix is just the right size for the feed horn
of an LNB for the downlink side, nestled in a hole in the helical antennas
aluminum reflector disc. There are 3D-printed parts to support everything,
plus a cone-shaped radome to keep it all safe from the elements.
It looks like a great design, but sadly, North American and East Asian hams
can only dream about building one, since QO-100 is below the horizon for
us. Were jealous, but were still glad the repeater is up there. Check out
this article for more on how Eshail-2 got the first geosynchronous ham
repeater.
///////////////////////////////////////////
A Hybrid Helical Antenna for the Eshail-2 Geosynchronous Repeater
Posted: 04 Aug 2020 07:00 PM PDT
https://hackaday.com/2020/08/04/a-hybrid-helical-antenna-for-the-eshail-2-geosynchronous-repeater/
Amateur radio operators like to say that working a contact in space can be
done with a simple handheld transceiver and a homemade antenna. And while
thats true, its true only for low Earth orbit satellites such as the ISS.
If you want to reach a satellite in geosynchronous orbit itll take a little
more effort, and this dual-feed helical ice cream cone antenna could really
help.
Until recently, the dream of an amateur radio repeater in geosynchronous
orbit remained out of reach, but that changed with the launch of the Qatari
satellite Eshail-2 last year. Since then, hams from Brazil to Thailand have
been using the repeater, and UK-based [Tech Minds] has been in the thick of
the action. The antenna he presents is a hybrid design, needed because of
the 2.4-GHz band uplink and 10-GHz downlink on the satellite, also known as
QO-100. Both require a largish dish antenna, with the downlink requiring a
low-noise block downconverter (LNB) and feed horn. The uplink side of [Tech
Minds] antenna is a helical design, with three-and-a-half turns of heavy
copper wire and a tuning section of copper strapping that attaches directly
to an N-type connector. The helix is just the right size for the feed horn
of an LNB for the downlink side, nestled in a hole in the helical antennas
aluminum reflector disc. There are 3D-printed parts to support everything,
plus a cone-shaped radome to keep it all safe from the elements.
It looks like a great design, but sadly, North American and East Asian hams
can only dream about building one, since QO-100 is below the horizon for
us. Were jealous, but were still glad the repeater is up there. Check out
this article for more on how Eshail-2 got the first geosynchronous ham
repeater.