What happened to Car Radio Antennas?

My ~15 year old Honda estate had in-glass aerials in the rear side windows, Itwas AM/FM only (maybe LW too) but I do remember it picked up 'buzzing' when going under electricity pylons, probably just on MW.

Next car (audi) had DAB, I don't know where the aerial was, but it did have a sharkfin, which seems like it was just for GPS which the car didn't actually have.

Current car also audi has DAB and I believe the sharkfin is combined GPS and DAB, reception is improved, but I think that's as much due to in-fill in the DAB transmitter network here.

[snip] [snip] 1971 year Cadillacs [1] had at least their FM antenna as a pair of wires embedded into the front windshield. They entered at the bottom center, spaced about 1-2cm apart, and ran vertically in parallel up the center of the windshield until about 3-4cm from the top, whereby each turned 90 degrees from the other and ran horizontally in opposite directions along the top of the windshield for about 0.3m or so each. [1] Other nearby model years likely had the same, but I have no direct knowledge of any of those years

t are boosted and fed into a selector unit that sends the stronger one to t he receiver. This is called "antenna diversity" as is commonly used with ra dio mics.

In the mid '70s (I believe), there were kits available that contained a thi n wire antenna that was attached to single-sided clear tape that you could apply to the inside of the windshield. A leader was attached that was plac ed inside the A-pilar down to and then behind the dash to the radio. I did a few installs on the family vehicles. Some vehicles are easier than others. The reception was mediocre on both AM and FM bands.

IIRC, my parents' 1992 Buick LeSaber had an antenna inside the windshield. J

I'm sure the car manufacturers could give you even more tricks about how to boost 5G transceiving.

My '76 Chevy C10 pickup truck has two lines running up the center of the windshield that split off -- this is the car antenna. Some parts on the truck were from an '86 - so I can't prove if this was a feature from the '86 or '76. I'd imagine it would make replacing the windshield a bugger if you wanted to keep your antenna in working order.

Michael Trew wrote: ================

** All these alternatives to the time honored telescopic whip are compromised. 1. They are *directional* - complete null in two possible orientations.

1. Framed in a steel structure so partially Faraday shielded.

Guess having no ugly antenna sells cars to those who value cosmetics above results. No wonder the are many "after market" alternatives available.

..... Phil

Personally, I'd rather have a full whip antenna. I owned a '99 Chevy (Geo) Metro that had a retractable one.

Michael Trew wrote: ===============

.... Phil

Over here, the FM radio network was originally built with horizontal polarisation. Maybe not much thought was spent on it, and it was done just the same way as TV was done. Or maybe they had some valid reason for it that did not work out as expected.

Anyway, that of course did not work well with typical car antennas of the time. So at first, vertical polarisation was "added" to the antennas (making it circular, I guess, depending on the phasing it could also be slant polarisation). And later, when the antennas were completely replaced because the contract to transmit FM signals went from the incumbant telecom company to a commercial company, they switched over to purely vertical polarisation.

Ironically, now the cars tend to have antennas that are more horizontally polarized. But hey, they do not want us to use FM anyway.

Rob wrote: =======

** Not sure just where you are - but the same occurred in Aussie land in the mid 1970s.

** Initially all FM Tx was horizontal here.

It was expected that TV antennas would be the norm and FM car radios hardly existed. In any case, the main broadcasters were classic music oriented so not so car listener concerned. Then it changed, commercial broadcasters started up and went for circular antennas.

** Your average "invisible" car antenna tends to be horizontal.

Heinrich Hertz would not be amused ....

...... Phil

Haha, not a power one. I can't remember the last time I've seen a car with a power retractable antenna.

Similarly for Schmart Fones. Selling either 'glitz' or 'cheap' wins hands down. Audio fidelity comes in _far_ distant.

I don't think a loop aerial on a car window would work at all well surrounded by the much bigger thinker more conductive loop consisting of the metal body of the vehicle in which the window is fitted.

I think it'd be better to just use it all as a short wire antenna much like the short whips even for MW and LW.

But most cars nowadays only have FM and DAB+ anyway.

--
Brian Gregory (in England).

Horizontal polarization is supposedly attenuated slightly less over long distance.

--
Brian Gregory (in England).

Michael Trew wrote: =============

** Google "power antenna" and you get hundreds of hits for new replacements. Manual ones went out with the Dodo.

They always seemed to somehow get damaged....

...... Phil

Brian Gregory wrote: ===============

** Not true. AM loops sense the magnetic field of the incoming EM wave. Some are made from co-ax with the outer shield grounded to eliminate the E field. Less static noise that way. The nearby car bodywork has little effect on a window loop.

..... Phil

One would think that the power ones would fail more easily.

I've never seen a car with a radio without am AM tuner.

Perhaps that's the difference between the USA and Europe. I can't remember seeing a car radio with MW here in the UK in at least the last

10 years - probably more like 20. Anyway, I miss the standard repair sometimes seen here many years ago for telescopic antennas - a "reshaped" wire coat hanger!

--

Jeff