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Thread: How to get the signal from an external antenna placed in a tower down to the ground?

  1. #11
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    Quote Originally Posted by microtony View Post
    Height makes little difference for ADS-B since it is ground-to-air (other than clearing obstructions).
    Very true. However, over here in Africa we do tend to have rather large and high trees, thus one needs have an antenna at least 10meters/30feet above ground. Doing that very experiment of height / range at present, and with an antenna that's 6m above ground, I barely get 180km range with a 3.5 element coco. Where my 8 element coco on 14m AGL gets +-400km. My problem lies not with high buildings, but with trees and topography.

    I would not mind having access to that nice mast over there in Cotonou..... !

  2. #12
    First officer 1090 MHz's Avatar
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    Quote Originally Posted by peterhr View Post

    It would be good to see if you can receive any ADS-B signals next to those cellphone antennas.
    Benin does use 900Mhz GSM according to Libercom, Spacetel-Benin and Telecel Benin so forget using a broadband dongle next to those antennas.

    The good news is the OP says he wants to use a Radar Cape as his receiver which does have a 1090MHz SAW filter. .

    http://ads-b.ca/1090/1090-saw.jpg

  3. #13
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    Quote Originally Posted by Xanderix View Post
    I may have access to a very high tower here at our research station in Cotonou to place an antenna and receiver. I have read something on the receivers/antenna's that are placed high in communication/telephone towers and that give an excellent coverage. Can't find the article back though.

    Suppose I could place an antenna in a tower, then how to get the signal down to the receiver? I assume the Radarcape receiver is not placed next to the antenna? Doees it need additional equipment?

    thanks for your time!
    I noticed this post late... hope you are still open for me to chip in. Do you have a budget for the antenna?

    This antenna should help - it is the Active Diapason PCB antenna. It is smallish, has SAW filter that can block GSM signals and ensure you get 1090mhz, comes with a LNA that gives you about 21db gain so is good for long cables and you can use a H155 20m cable (long enough?) from the top of the tower to the ground. It isn't cheap, but it will fit your description well especially you are thinking of getting the radarcape.

    Here is the link http://www.shop-modesbeast.com/epage.../Products/1401 or http://h2204566.stratoserver.net/Sma...z#.U5JUN_mSx8E

    I recall a post in Aussie feeders that a user also uses towers to place his ads-b antenna and the receiver could not detect the mode s signals as it was overwhelmed by the GSM frequencies. Only Using a preamp with build in band pass filter/front end filter sorted that issue. Link: http://forum.flightradar24.com/threa...ll=1#post52030 But the context here is he is using a mode s beast, which is a very sensitive receiver as designed by Gunter. Not sure about the dongle though, but there will be an effect on 1090mhz reception I suspect.

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