Clip on DAB aerials?

[ellal]

Are there any DAB extension aerials that can clip on (or attach otherwise) to an existing DAB radio aerial which work, as the Radio I have does not have an unscrewable aerial.

 

[Sam Gangee]

No but you could experiment with a long piece of wire.

Problem with trying to receive a weak signal, without having an aerial above the roof, is that the "indoor" aerial will receive more unwanted interference than wanted signal. The interference will "deafen" the radio.

 

[ellal]

Sometimes the signal is ok, but we often get 'squelching'...

So not sure if its a weak signal or just inteference.

 

[Sam Gangee]

The two go together; a weak signal is more susceptible to interference.
Did the length of wire help?

 

[ellal]

Haven't tried the wire yet.

Just a bit of copper pinched out of a bit of T&E?

 

[Sam Gangee]

Yes, any wire should do. Insulated or not. But don't hold it while testing because you'll effectively "ground" the signal.

 

[ellal]

I'll give it a go and report back.

Cheers

 

[ellal]

Sadly it made little difference using the wire method.

 

[Sam Gangee]

The actual length and orientation will make a big difference. DAB signals are vertically polarised so the wire needs to be hung vertically and as high as possible. I used to do my testing in the bedroom with the wire thrown over the roof or dangling from the window. Then shorten the wire by chopping off 100mm at a time and retesting. One major problem is that this wire will pick up interference that could swamp out the DAB signal.

If that doesn't help then you'll have to dig inside the radio and solder coaxial cable to the aerial point and to a nearby 0 volt point on the PCB and hope that the impedance matching is good enough. The cable can be connected to a proper DAB aerial outside.

 

[ericmark]

An end feed dipole should be λ/2 in length which is approx 143/ƒ so since DAB is 174.928 – 229.072 MHz then wire should be 0.62 to 0.82 meters long. In the main one has to double of half the length odd lengths between don’t really work but it is looking at a straight wire so once you start to put the wire at odd angles it does not really work.

I wanted to talk to my friends on the Falklands and also listen to BBC world services for the latter I poked a long wire through the vent of my steel container cabin and intended to walk outside to talk to friends on 144.500 Mhz but found at night the doors were all locked an I could not get outside so tried using the long wire. Theory says it should not work but in practice it did. It was just wrapped around the build in aerial of my FT290 radio.

Personally I use freeview and free to air to listen to digital radio mainly as I have the boxes, but will admit it’s a pain as there is only a number on the front panel and I have to tune using TV and then turn off TV once tuned. DAB was designed for cars really but the take up was slow and in Wales where I live it has been a complete flop. Everyone uses the old VHF FM transmission. Personally I think DAB is a waste of spectrum since all is also on TV frequencies both satellite and terrestrial for home users and it simply does not work in a car in Wales. OK in London it may work but I would not install a radio for just when going to England.

We see figures like 94% coverage but that is worked out according to population density so since 94% of the population live in towns and cities that means no coverage in the majority of Wales.