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Chinese HF Satellite Antenna Thoughts/Selection

Discussion in 'Satellite and Space Communications' started by K4BAD, Jun 15, 2018.

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  1. K4BAD

    K4BAD Ham Member QRZ Page

    Howdy Everyone: The Chinese are scheduled to put a satellite into orbit in Sept. There will be multiple transponders available. ….15 meters up and 10 meters down,15 meters up and 70 cm.down and others.

    I know it's very premature to give much thought about appropriate HF antennas,etc at this time....but I'm doing it anyway.Yup I be bad(pun intended).

    For me,HF beams are out of the question. So,I'm thinking about a hand rotatable 15 meter dipole for uplink and a small ground mounted 10 meter vertical for downlink....or the reverse. Will be using an ICOM 7300 and an ICOM 7000 in some combination. Don't really know what would be best ant. choice.

    Comments ,particularly from sat.ops with HF sat experience,would be appreciated.

    Thanks for reading....73 K4BAD Harry
     
  2. N4UFO

    N4UFO Ham Member QRZ Page

    I worked RS-12/13 (15m up/10m down) with a multi-band vertical and later with my mini beam. The biggest thing that helped me was a 10m preamp to better hear the downlink. And the downlink is where I would focus my attention. On the uplink, most HF stations can muster more than enough power to be 'heard by the bird'. ;)

    The tuning convention back then was to pick a TX frequency, make sure it is clear terrestrially and then NOT MOVE it. Because you don't want to be fiddling around and tune on top of an ongoing terrestrial QSO. As a result, you simply tuned your downlink to hear 'the other guy'. You didn't worry, like you do know on VHF/UHF birds, about keeping your signals together on the downlink. Again, preventing QRM to ongoing terrestrial QSOs being the reason. BUT, this was all before automatic tuning, the 'one true rule' and all that. What will end up being the convention, I don't know, but I hope that folks will consider the potential QRM issues to regular HF users.

    Anyway, bottom line... full duplex on 15m/10m sat contacts... was never an issue. MOST stations were using a single rig and never heard themselves anyway... again, just tune in the other guy. - Lots to consider... :)

    73, Kevin N4UFO

    P.S. I was AC5DK back then... google that call and RS-12 and it used to get a bunch of hits... I even earned VUCC-Sat #86 on just that bird.
     
    K4BAD and WD9EWK like this.
  3. WD9EWK

    WD9EWK Ham Member QRZ Page

    The consensus on the AMSAT-BB mailing list seems to be "use what you have", whatever that happens to be - dipoles, verticals, Yagis, etc.

    It will be interesting to hear the HF downlink from that satellite, since - unlike N4UFO - my only satellite experience with an HF downlink is AO-7 in mode A, around 29.450 MHz. That's always a tough one for me, and I have only one mode A QSO in my log to show for my efforts. For portable operations, HF means larger antennas, so that will require more time to set up than I do with a radio or two and my Elk log periodic. In any event, I'll give it a try if it gets launched and becomes operational.

    73!
     
    K4BAD likes this.
  4. AI3V

    AI3V Ham Member QRZ Page

    Back in the days when I was on rs7,8,9, etc what worked well was a low dipole.


    A turnstile is ideal.

    For more overhead passes.

    For horizon shots, a beam is nice, and a Marconi works , obviously with less gain, phased arrays would be better than a single vertical.

    Watch the ionesphere, sometimes the signal will interact with the earth side and be heard when the bird is not los.

    Other times the downlink will interact with the space side of the ionesphere, and the satellite will be inaudible even tho it is in los.

    Also, expect interference from stations unaware of the bird.

    Rege
     
    K4BAD likes this.
  5. AI3V

    AI3V Ham Member QRZ Page

    A note on full duplex.

    I consider the ability to monitor your downlink signal a requirement.

    Rege
     

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