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No. of Antennas for 2khz to 2Ghz say?

Discussion in 'Scanning & Shortwave Listening' started by c2014s, Nov 3, 2014.

  1. c2014s

    c2014s
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    I'm wondering how many antennas are needed to cover the range of say 2khz to 2Ghz? The exact bandwidth is adjustable, its a broad question. I am relatively new to this hobby so go easy on me please lol.

    I am hoping to pickup all sorts of intriguing signals whether its marine or space station etc i guess as my interests polarise into a given area i will look into more specialised antennas for specialised jobs.



    I have a rtl sdr type reciever that i am in the process of modifying to receive a broader range.

    There are sooo many many antenna types and suggestions but none as simple a question as mine.

    The answer maybe impossible I have looked into discones from say 20Mhz to 2Ghz but cant get a straight answer on the lower range.

    Thanks in advance for taking the time to read this.

    All the best
     

  2. Justme

    Justme
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    I build my own HF receiving loop amplified with an long tailed pair of BFW16A's, good from 10 KHz to 70 MHz.
    A discone has a 1:10 range maximum, so using a 50 MHz discone would be just usable to 500 MHz.
    Then you still need an antenna for the rest 500 MHz to 2 GHz.
    You can make your own small discone that would work from 500 MHz to 2 GHz,
    Discones are broadbanded, no gain antenna's and not the best there is but you sacrifice performance for broadbanded use.
    All antenna's for 50 MHz and up should be placed as high up as possible, use high quality low loss coaxial cabling as well, losses there are quite great in normal coax, use good (N) connecters.





     
  3. c2014s

    c2014s
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    Wow thanks that was quick so the answer is 3 ish cool guessed-cum-hoped it could be that.

    Yes i was hoping to make the antennas myself and have the necessary skills (i think lol).

    So the next two follow up questions are...what cable could you recommend please? How would i go about switching between the antennas or can they be connected together? I have been pulling my hair out trying to find these things out over the past few months and years. Too self reliant to ask for help lol. Also hoped my question would help others too. Thanks a lot for your help Justme!
     
  4. 222DBFL

    222DBFL
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    I would recommend good coax like times microwave lmr400,
    N-Male type connectors, and a good antenna switch box. The antenna switch box will let you switch between antennas. Get a good one. I am sure others will chime in as well. Have fun building the antennas!! God bless.
     
  5. Justme

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    Coaxial cables differ here in the Netherlands/Europe from your side of the pond, but the Times Microwave LMR 400 is roughly the equivalent I use as Aircom plus low loss coax, so a good choice for anything up to 500 MHz.
    Depending on the length of the runs of coax to your antenna's you might need an even better low loss coax for the antenna from 500 MHz to 2 GHz.
    N connectors are the only choice above 30 MHz.
    If the antenna's are only used for reception you might want to look for a amplified broad banded antenna that replaces 2, anything from 30 MHz up to 2 GHz can be found here and also commercial amplified antenna's for short wave.
    They are quite expensive but then the demand for very expensive coax becomes less of a problem and you can pick a bit less expensive coax with a bit more loss because the amplifiers in the antenna's will overcome the loss in the coax.
    My amplified loop has a run of el cheapo RG 58 of 90 feet on it and the amplifier doesn't have a problem to overcome that and produce good signals here on the FT 2000 - D.
    I also have an inline amplifier here that will amplify anything from 24 to 1500 MHZ the PA - 15 I once bought on a ham radio sale.
    I know there is another version that will do 20MHz to over 2 GHz, but I only needed this one for an experiment.

    So, simply said, use unamplified antenna's and extreme good coax with low loss. specially on anything above 500 MHz, or use a dedicated broad banded antenna with amplifier(s) and you can get away with les expensive coax , even with just 2 different antenna's, one for 0 - 30 MHz shortwave, and one for the rest.
    And don't re invent the wheel, enough people around here to give answers ;)

     
  6. c2014s

    c2014s
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    HI there 222DBFL, thanks a lot for the suggestions and i have checked in UK where i live and can get the lmr400 by the meter so that will be on my list of things to buy. Much appreciated all the best, cheers.
     
  7. c2014s

    c2014s
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    Wow thanks again Justme, you have given me a lot to mull over there. The amplified cheapo / unamplified dear coax idea was one i hadn't considered at all.

    Have checked availability of the Aircom as well as the LMR 400 in UK, where i am and can get both ok, need between 5m and 10m to loft above my head. Also had a look through my component drawers and have found some very useful RF stuff in there i didn't realise i had or thought i might not need like the 3n201, bsw68, and some uhf/vhf amplifier chips, i was given a box full by a friend 10 years ago and have only just got back into electronics. Will have a look for some amplifier and discone designs later. Liked the dont reinvent the wheel comment..lol..very much applies to me at times.
    Take care and thank you very much for your help.
     
: antenna, sdr, discone

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