Antenna size for edge of footprint reception (3.9 degrees)

    Hi everyone, can I introduce myself and ask a question about antennas. I'm Simon, a British radio ham living in the beautiful country of Laos for many years and operating with the callsign XW0LP. I'm usually active on HF only because my current location in the town of Luang Prabang has too many high mountains which block the low 3.9 degrees antenna elevation that's needed for a line of sight to the QO-100 bird (I'm right on the edge of the footprint). Also, there are no motorbike paths up to a high point on the mountains.


    But soon I will move to the 'party ' town of Vang Vieng. (At my age I'm past partying...). That town also has no LoS but there are nearby mountains with paths accessible for my motorbike up to the top at about 1,400 meters above sea level.


    My question is: assuming a clear line of sight over the mountains from my high location, what size of solid parabolic dish would I need to successfully receive/transmit on the narrow band transponder from my location on the edge of the satellite footprint? The receive path is probably the important factor because my receive S/N will be determined by my dish size and LNB noise figure. (I purchased a stable Bullseye 10 GHz LNB from the RTL website sometime ago).


    If I need a large (say 2 meter dish), then my 'project' is not easy to implement because I must carry the dish on my motorbike. A 1 meter diameter dish is OK to carry (maybe not in EU, but here in Laos I can carry a dish of this size on my motorbike and the police will not stop me!).


    Thanks for your advice - Simon

    • New

    A very late reply :) I was unable to find a nice house to rent in Vang Vieng. So I stay in Luang Prabang and must therefore take my satellite antenna and equipment on my motorbike and up into the hills so that I have a clear view of QO-100. That's not a problem and I have tested my system with a 90cm dish to receive the local Laosat transponders and it's working OK.


    But how can I align my dish onto QO-100, since the required elevation angle is only 4 degrees? I have my compass and inclinometer of course, but are there any strong Ku band satellites 'close' to the E'S Hail bird that I can align up on first? (I think not...)

    • New

    Hi Simon,

    the QO-100 with its narrow band transponder will show a characteristic picture, two beacons at the edges and one in the middle. My recommendation is to use a wide spectrum for searching with more than 500 KHz. Do not look at a specific signal but at the peaks of the beacons. Don't care about the exact frequency of signals but try to optimize the levels first.
    My "search equipment" is a bias tee, a little battery and a RTL-Stick, I prefer SDR#. It is completed with a small laptop. This all is idependent from the radio and can be used even if the dish is outside. I am not sure if you will "see" the transponders basic noise floor? With high angle elevation like here in Europe the noise is a very good indicator for fine adjusting a dish. It is totally independent from any frequency.

    When will you start with your activity? Probably this will give a heavy pile up.

    73s
    Andreas