1. Join Now

    AVForums.com uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.

DAB and FM combined aerial

Discussion in 'Music Streamers' started by laalves, Feb 25, 2005.

  1. laalves

    laalves
    Active Member

    Joined:
    Feb 6, 2005
    Messages:
    493
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    21
    Location:
    Cascais
    Ratings:
    +8
    I'm now considering an external aerial for my new home and my T32R. I've been hunting around and seen only cumbersome multi-element FM-only aerials and DAB-only aerials.

    Then I thought: what about automotive aerials? I checked Blaupunkt and they have a combined AM/FM/DAB car whip-antenna, very discrete, fed with 12V with gains of 7 to 10dB, depending on the band. Model is A-DR T 01-M.

    What do you all think? Anybody tried this? It's not cumbersome, costs 60 euro, easy to install (just route 12V from an indoor small power supply together with the coax cable) and hardly noticeable....

    Luis
     
  2. GrahamMG

    GrahamMG
    Well-known Member

    Joined:
    May 8, 2004
    Messages:
    4,449
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    86
    Location:
    UK
    Ratings:
    +192
    Don't know, try it and see.....
    I doubt it will perform as well as a proper roof aerial though (and yes you need two).....
     
  3. edward

    edward
    Member

    Joined:
    Apr 2, 2003
    Messages:
    858
    Products Owned:
    1
    Products Wanted:
    0
    Trophy Points:
    32
    Location:
    Reading
    Ratings:
    +26
    A lot seems to depend upon how good the DAB signal is in your area. I went for a Dipole becuase it isn't directional and should therefore be more flexible. However, in my part of Reading the signal drops below critical strength every now and then so that I wished I stayed with a Yagi.

    May I suggest you find out about local signal strengthe before you start spending.
     
  4. ScottMoffatt

    ScottMoffatt
    Guest

    Products Owned:
    0
    Products Wanted:
    0
    Ratings:
    +0
    I have separate FM and DAB vertical dipoles mounted on opposite sides on my aerial mast.

    My distribution system has a single "VHF" input (47-230MHz), so I use a diplexer to combine the signals on to the one downlead.
    I use only enough gain at the amplifier to overcome the splitting losses - the distribution system does not boost the signals.
    If you only need the signals at one tuner, you'd use a diplexer on the roof, with the output co-ax going straight to your tuner.
    Diplexers are passive - they need no power supply.

    Actually, it's a triplexer I use - 47-108, 174-230 and 470-860MHz bands.
    This is because I couldn't find a decent outdoor FM/DAB diplexer at the time.
    The unused UHF input is terminated with a 75-ohm resistor.

    It's also important that both the FM and DAB aerials have BALUNs in them. BALUN means balanced to unbalanced - a dipole is symmerical (balanced), but co-ax is unbalanced (one side is earthed). The balun ensures optimal signal transfer.
    If you use "economy" aerials without baluns, it upsets the performance of the dipoles, meaning that the co-ax screen can also act as a receiving element.
    This degrades the signal quality, making the aerial installation more susceptible to the effects of traffic etc.

    I don't know why one of the major manufacturers doesn't make a dual band "trapped" dipole - one simple aerial with one co-ax connection for both FM and DAB.
    Such items are common for multiple amateur radio bands.

    Regarding the car antenna, I'd suggest it needs a large ground plane to work efficiently, as it would have when installed on the roof of a car.

    Scott.
     
  5. Sveinb

    Sveinb
    Standard Member

    Joined:
    Feb 11, 2006
    Messages:
    2
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    1
    Location:
    Bishop's Stortford
    Ratings:
    +0
    I use my fm areal, with a splitter bought from Maplin for a few quid. Works perfect in Bishop's Stortford which generally has a weak transmitting signal. received signal in my Sony STB900 is region 93-100pct.

    Svein
     
  6. GrahamMG

    GrahamMG
    Well-known Member

    Joined:
    May 8, 2004
    Messages:
    4,449
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    86
    Location:
    UK
    Ratings:
    +192
    Scott does what I have been advocating to everyone for years..... Oh and one aerial for both DAB and FM is a lot more complicated to get right than it might appear which is why you won't find one.... I use a tri-plex amp (using all three inputs as I have a big UHF for "freeview" as well), I'd look one out that has individual gains for each input so that you can balance them, it improves performance more than you might imagine.....
    The thing is that some people may get great reception just with the stub aerial TAG latterly supplied, not everyone is so lucky hence the stance of doing it properly and not doing just enough...... It isn't that expensive or complicated to do compared with the outlay for the TAG DAB unit in the first place..... The TGA DAB unit deserves no less.....
     

Share This Page

Loading...