Car aerials

The shark fin aerials have a built in amplifier, so may well jbex better.

But the car has to feed power up to the shark fin, which it is unlikely to do for the standard C3 aerial ... so it's not a straight swap.

Unless the radio has a phantom power facility, but even if it does, how would you enable it !

Rather than everyone pontificating about what may work, why not do some DIY and check the cable from the antenna to the radio is actually, you know, connected and not broken?

The "shark fins" usually comprise a GPS and a GSM antenna. When these are fitted the FM radio antenna is normally combined with the rear window heater structure. John

The radio works, but as if the signal is weak in areas where my former car had no problem. Removing the aerial removes any signal as you would expect.

The technology seems to be tolerant of "flooding with multiple transmitters".

CE15 BBC National DAB UK 12B 15 416 <=== Yikes!

The (relatively) cheap RTL-SDR receivers (silicon RF tuner plus RealTek DVB chip with analog to digital converter for sampling), if someone has coded up a Software Defined Radio routine for DAB, you can extract signal strength and channel performance info, while testing your antenna. Probably the hardest part of the project, is making an adapter cable to go between a DAB antenna connector and the connector on the RTL-SDR. The RTL-SDR can convert your desktop computer or laptop, into a radio receiver.

Just pop rtl-sdr into

Paul

The O/P hasn't mentioned which technology is in use (DAB/FM/AM)

I am mainly interested in FM, but would quite like AM for BBC 5 live football. DAB is pretty useless round here. so no loss.

Where is 'here' ? In my experience, unless you live literally in the middle of nowhere, the BBC National DAB mux coverage is very extensive.

Forget AM, the Beeb have said they expect to ditch R5L on AM in 2027

Tyneside UK

If what you say is true, then my problem is worse than I thought as I get no stations on Dab although, clearly, the previous owner did as there are Dab stations programmed in that get no signal now.

Have a look at a DAB map?

Well, that depends upon where they lived/drove.

My suggestion would be to stream via bluetooth from your phone. More choice of stations and if you listen to BBC you have catch up.

Those maps are for small scale flea powered local DAB muxes, not the main BBC national one.

If it's Tyneside, the area has multiple transmitters for the BBC DAB mux, I've never seen a recent map, only dumbed down Postcode Checkers, but here's the coverage from 2008, when the number of transmitters was only about 100, it's now over 400

Try switching loads of stuff off. Something, usually a swichmode PSU, if creating a load of RF hash which is covering up the wanted stuff. Likely to be more than one offender.

I'll second that. It's a very long time since I last listened to real wireless in the car.

DCF77 longwave time signal, can be picked up with a tuned LC, where the L is a coil of wire around a Russian piece of ferrite core. Apparently, nobody else makes that particular ferrite which is intended for longwave applications.

AM uses an LC coil (C can be a variable capacitor for tuning) and a ferrite core. It does not necessarily require a "long wire" antenna. The selectivity of AM receivers isn't all that good. Also of note, AM radios do not work in BEVs due to electric motor commutation noise polluting the reception :-) Similarly, maybe a hybrid would occasionally have problems like that.

At higher frequencies (~100MHz FM, ~200MHz DAB), I don't think I've seen a ferrite core or a powdered iron core for such things. If anything, it might involve air cores and "pieces of wire". A telescoping single antenna (as used on cars in past decades), or even a TV rabbit ears, can pick up 100MHz to 200MHz, if you adjust the length of the telescoping bit. At lower frequencies, the signal has better penetrating power through buildings or through semi-faraday cages.

The AM/FM transmitter would be a single transmitter, and you would not want a directional antenna (a yagi) on the roof of the car, as that would almost never see a signal. The antenna needs to be omnidirectional.

MY AV receiver, came with dangling bits of wire, some of that 300 ohm twin conductor flat cable, and the antenna part might be ~150 ohms and there would be a slight loss from the standing wave ratio.

I don't know if patch antennas or fractal antennas would be meaningful or effective at those frequencies. That would not prevent the equivalent of a Radio Shack, from selling you such items (unknown mystery meats, underneath the plastic, reason for a high price for the thing is unknown).

Paul

See if you can pick up an RTL-SDR, some sort of DAB antenna (so you can go out in the yard and play with it), and with DAB code loaded in a computer while the SDR is plugged into a USB port... you can scan for DAB activity and signal strength.

My guess would be "the cable fell off" somewhere in the car :-) Maybe the last time some goon at the auto shop took the dash apart, the antenna cable didn't get hooked back up.

Digital reception is subject to an abrupt LOS, compared to fringe FM reception. The signal level between "I can hear music" to <receiver-squelched> is only 2dB or so, so maybe if the antenna signal is at -54 and you hear music and if it drops to -57, the receiver squelches and no garbage noises at all come out of the speakers. That is the kind of behavior you would expect to see in a digital receiver with packetized data.

That multiplex with the 400 transmitters, you have *got* to be able to detect some sort of DAB signal at that carrier frequency.

Paul

Nothing special about the ferrite. Old AM radios had MW/LW on same ferrite

Dont need to use anything to receive a radio signal beyond a long piece of wire.

The ferrite is there to form a compact way to make a tuned circuit to select the ones you want from the ones you don't.

I have, But then I was into designing stuff in that band at various times. Does tend to be more air cored though - less losses.

Anything can pick up anything, Its all a matter of how well

The purpose of a modern car antenna is to get something outside the skin of the car so that it receives what's outside and not what's inside.

If the inside stiff is affecting the radio then the outside antenna is not working as it should