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Radio reception

Discussion in 'General Electronics Discussion' started by Deigh, Jun 17, 2015.

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  1. Deigh

    Deigh

    169
    8
    Apr 26, 2011
    You would expect better of a man of my age but........Having lousy reception from VHF radio in our new flat. Decided that the cause was a wornout set. Found a nice new one at a well reduced price and put it on the credit card. Got home and found it was as bad as the previous one. Now the brain starts to work and I realise that we live in a corrugated iron roofed house with aluminium doors and windows and of course that makes it a Faraday Cage. A bit of messing around with wires and a splitter and I have the set using the TV aerial with great results.
    Can't take the new set back, it is sales goods and unreturnable. Bugger.
    Anyway, lots of people live in these houses in New Zealand and have problems with radios and are not always able to jump the antenna to a nearby TV. So....Has anybody got an alternative way of getting a signal into their house?
    Deigh:(
     
  2. hevans1944

    hevans1944 Hop - AC8NS

    4,455
    2,073
    Jun 21, 2012
    Sorry, Deigh, you must have an antenna outside attached to a wire, usually coaxial cable, leading inside to get a decent signal inside the type of building you describe. Remember the old "rabbit ear" antennas that used to sit on top of the TV? People would hang aluminum foil on them and bend the two "ears" all over the place in an attempt to improve TV reception. VHF is tough, and UHF was worse. I am amazed that my cell phone works (most of the time) indoors!
     
  3. Deigh

    Deigh

    169
    8
    Apr 26, 2011
    Yes, the fact that my cell phone works indoors was one of the reason I put the question to the forum. In theory the Faraday cage should prevent that from working at all.
    Deigh:D
     
  4. davenn

    davenn Moderator

    13,552
    1,850
    Sep 5, 2009
    it depends on the size of the holes in the cage
    a Faraday cage that will totally stop AM radio may have holes in the grid that are a couple of metres across
    but it will still let much higher frequencies pass through

    the smaller the holes size, the higher the freq that will be stopped ( you could consider it as a hi pass filter)
    have a look at the holes in the grid on the door of your microwave oven .... they are quite small. Their cutoff freq is somewhat above the 2.45GHz that the ovens all work at, but there is enough of a hole size to allow light to pass through so you can see what is being cooked/heated

    the holes need to be at least 1/10 of a wavelength ( from memory) at the freq of interest to be effective

    Dave
     
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