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MG MGB Technical - Radio aerial solution

My '67 GT has still its Motorolla radio functioning. The problem is that attempts to fit a wire aerial along the windscreen (to remove the need for external one) doesn't give good reception. The radio functions over the MW/LW bands.

The wire used is very thin, giving a resistance of approx. 120ohms over 1,3m length. Is the resistance critical? I tend to think not as voltages induced by radio waves must be very, very small (problably a few pico volts). Running a thicker wire inside the interior of the car doesn't help ( maybe due to electromagnetic shielding of car body).

Can anyone suggest a solution, I would prefer not to fit an external aerial as it spoils the clean appearance of the mk 1 GT.

Many thanks,
Brian McIlvenna
Brian McIlvenna

Made use of the dead space below
/ behind the cockpit surround to
mount a standard antenna.

Strapped on using the surround bolts
and it's well hidden anyway.

Reception is not great but works well
'nuf. Really wanted to find a small
one to mount on the center rod but
could not find one to fit there.
HowY

I felt the same way about the lines of my Roadster so I bought a Bosch electronically boosted windscreen aerial. Works sort of OK in strong transmission areas on FM but the signal is easily disturbed by other vehicles especially if they are large. Long wave is very poor and short wave - forget it.
I'm now going to install a DAB radio so I have at least to get a conventional DAB aerial and as I don't want to have the car bristling with aerials all over the place I shall get a dual DAB/analogue aerial. Pricey but the best solution for a small car. Frankly I don't think that there is any substitute (unfortunately) for an external aerial. However, mounting it on the rear will save the lines of the front of the car - which in my view(sic) is the best bit.
Marc

So how does my car manage to produce fantastic stereo, and pull in all sorts of stuff from Europe, all without an external aerial, on FM, MW and SW.
Bill

Bill,
We don't know, why does it? What type of antenna are you using?
David

Yes, come on Bill tell us how you did it. We're all bristling to know.
Mike
Mike Howlett

Most aerials/antennas are compromises at best. The problems encountered by wire antennas often stem from two things.

One is that many wire antennas which fix to the windscreen (or rear window) are laid out in a horizontal position. This is done either to gain maximum length for signal strength and approximation to some fraction of wavelength, or because the antenna is a dipole, often used to optimize reception for FM. The problems with this layout is that these antennas become much more directional in relation to the broadcasting antennas which are usually oriented vertically to give 360 degree coverage from the transmission site. Because of this directionality, the signal often goes up and down in strength because of variance in the ability of the antenna to pick up the signal and also because of phase cancellations of the radio signal on FM from Multipath signals bouncing off of large objects.

None of this helps, even with a vertical mast antenna, but is made worse by the proximity of many of these wire antennas to the sheetmetal structure of a car. Because of their horizontal orientation, several effects of shielding and reflection then show up which affect vertical mast antennas much less, since that type nominally sets at right angles to the ground plane of the car created by its expanse of sheetmetal. If you have noticed communications antenna installation on commercial and government vehicles, you will most often see them vertically oriented, often from the roof or deck lid, and that is because they radiate more effectively and over longer distances in that manner. Reception is, for the most part, the reverse of radiation, and so a vertically mounted receiving antenna will also be more effective than a horizontally mounted antenna. If you absolutely, positively have to use a horizontal wire antenna, you can probably help it along with both a signal booster AND a receiver with a really decent tuner section. Some of the Pioneer and other aftermarket units have tuners which handle some of these problems I mentioned incredibly well, which says something for digital electronics and the ability of tuners to compensate for crappy signals.

For my part, I use an automatic fender mounted vertical mast antenna on my GT which keeps the hoodlums at bay, the car looking ok at park, and gives reasonably good reception of AM/FM even across the sparsely populated American West. FWIW
Bob Muenchausen

Bill: Are you running XM or Sirius? ;-)
Bob Muenchausen

Bob,

I have a Sirius receiver in my Motorhome and love it except for one small problem. The installers put the antenna on the slope of the roof over the running lights which makes it a little directional with certain satelites. I havent taken it back as yet to get it placed properly. However having said that, these kinds of radios could very easily replace cd changers as the quality and variety is exceptional. Sirius has too many channels to count and music to suit anyone... no I dont sell them.

CW
CW Strong

To answer xx question, the answer is no known aerial as far as I've been able to asertain.

There is an aerial lead in the car wiring, but someone told me it probably goes to the rear widow heater elements, or even the windscreen, as both have very fine wires as elements.

What I wish to know is, what can we successfully hook into on the MG.
Bill

I'm a radio buff and I wouldn't mind knowing what radio you have installed. Also you say that the aerial wire is in the car wiring. Does this mean that you aren't talking about an MG?
Marc

Bob M's comments re orientation are well taken. The FM antennas can be a classic half wave dipole design but the long range bands antenna is inferior, as a half wave antenna would be over 100' in length depending on the band. Virtually all transmission antennas are vertical in orientation, hence better reception with a vertical recieving antenna. I note in my '01 GM coupe that the antenna is two wires in a narrow V shape in my rear window begining at the bottom and extending upward and forward, obviously as the window slopes. The reception for FM bands is the best I have found in a vehicle to date. The GT has a window which could accomodate such an antenna.
In my mind I've always had doubt regarding the effectiveness of a dipole located in the rear window near the top of the glass. The location of the metal frame nearby would alter the characteristics of the antenna. The vertical antenna in the center of the glass makes sense from a radio wave point of view. AM or MW or classic Short wave is probably best served by the classic telescoping external anntena. Most car radios have the ablility to be "tuned" for a specific antenna by a screw adjustment at the rear of the radio. The adjustment is by necessity a compromise, as what would be good for one end of the band may be poor for the other end.
Barry
Barry Parkinson

Re Marc, London's comments, I'm talking about my proper car, a BMW, and the radio fitted is just a Sony with the usual CD etc, nothing special, except it performs faultlessly, no interference etc, and certainly no ghastly external aerials.

My comments regarding the aerial lead being in the wiring are based on memory, I just can't imagine how the radio gets its signal feed otherwise.
Bill

Bill, I'm just a bit sorry that you don't consider that your MG is a "proper car". I suppose that you can actually hear your Sony radio in the BMW too: definitely not a proper car.
Marc

Proper gentlemen all, is there a known wire, windshield mount ( glue-on I'd guess)antenna applicable for the mgb roadster? After 33 years, I have the 1971 roadster looking as good as I've ever hoped. The idea of fender mounted ( retractable or no) antenna is definitely a pig that don't dance to my eye. Does anyone know of an option for the roadster?
vem myers

Vem:
A CD player. Record your own CDs, create your own Play lists. NO unsightly antennae, no multipath distortion, no signal fade, no pops, no clicks.
Bob Muenchausen

Break
My
Wallet

*winks*

CW Strong

I have great success with a Harada horizonal am/fm radio antenna. My radio is an Alpine 7000 series unit. The antenna comes with a 12v booster that must be wired in and of course the antenna cable must be pushed into the windshield rubber moulding.If you are interested in models numbers just let me know. I do not get to this thread very often.
Cheers
Jon Rosenthall

Gentelmen - I have a rather antiquated Panasonic AM/FM radio and cassett player in our MGB with a verticle, non retracting antenna. It seems to do an adequate job of bring in the stations we (my wife and I)like to listen to around town. Once on the highway, stations come and go as we travel in and out of their range, so we just shut the radio off and have never bothered with the cassett player because there is enough engine and road noise to drown out the radio (and I value my hearing too much to crank it up to where it is blasting over the other noise). We have probably spent too many years driving a TD with no radio, but we have come to enjoy the music of the engine and thought that was part of what MGs are all about. Cheers - Dave
David DuBois

I might be a bit rusty on the old electronics but if I remember correctly MW/LW is basically AM (as opposed to FM).
I seem to remember in my old radio kits the FM band used a wire length for the antennae but the AM band always used a ferrite coil antennae (I may have the name wrong.. but it was a coil of some kind). For better FM reception you could increase the length of the wire, but there was never a way to increase AM reception as the coil antennae was a pre-made component. Perhaps making your own coil-type was possible, but I never went quite that far with the electronic kits.

I don't know if it applies with auto radios, but I'm assuming the AM (or MW/LW) radio will have one of these short coil-type antennae inside. With that in mind I'm also assuming that external antennae on auto radios are purely for FM reception.

Don't take my word for it. This is just a semi-educated guess.

And for Bob Muenchausen, I advise upgrading to MP3. No moving parts and no skipping/jumping. Plus I fit 20 CDs on my pocket size MP3 player which plugs into a headphone jack coming from the amplifier in the boot. Best part is I never forget to take it with me and nobody has ripped my roof open to steal the stereo system anymore.
D O'Brien

Brian,

This discussion seems to have gone a bit astray. Your request was for simple MW/LW reception which is what I have in my GT. I have not solved the problem without the need for an external aerial but have fitted a period roof aerial. This fits immediately above the rearview mirror mount and the wire will go through the top frame and down inside the NS screen pillar completely out of sight. I seem to remember that it has to come to the surface for about 4cm at the top of the pillar to avoid a filler but that't it.

Try a branch of Lucas Service for the aerial. It's all chrome and set at the correct slope I believe it enhances the GT's appearance.

Iain MacKintosh
Iain MacKintosh

O'Brien: Point taken! You can tell I have never used MP3. ;-)
Bob Muenchausen

Apologies if I offended anyone with my comments about a "proper car".

My MG is currently having a most thorough restoration which is costing me, well I'll try not to think about that too long, I will get all faint.

What I mean is that I use a modern car for my day to day motoring, and will be looking forward to a spot of showing off, probably on a Sunday, and definitely on a dry sunny day, one of these days, when the darned project is finished.

Reminds me of watching paint dry.

I'm afraid power steering, automatic gearbox ( regarded as a luxury and therefore non essential in England ), and of course cruise control to ensure I don't do 31 MPH, in a 30 zone, thereby causing the local constabulary to divert their attention from lesser crimes such as burglary and mugging little old ladies, to pursue me post haste, for the PC crime of speeding, or should I say driving a car, have seduced me.
Marc

Go to scrapyard. Find an old Skoda Rapid (the coupe version of the Estelle range). If you trace the wiring from the heated rear screen you'll find a cylindrical cannister that the wires to the heated rear window connect to along with the radio aerial lead. Note the connections. Remove same and wire into GT rear window / radio.
For my sins, when less well-off, I used to drive a Skoda Rapid. I took note of this rather useful part in case I ever wanted to wire a radio aerial into the heated rear screen of another car, as it's the only car I've ever seen an accessible and seperate component that performs this function on.
T J C Cuthill

"Proper gentlemen all, is there a known wire, windshield mount ( glue-on I'd guess)antenna applicable for the MGB Roadster? Does anyone know of an option for the roadster? " Yes, there is an option - a hard to find fender mirror that has an antenna in it. It was, I believe, an option on the early Bs. I've seen a few around and sometimes they're on eBay.
Mike MaGee

Just out of interest, does anyone know why all the hundreds of bits of metal that make up the car can't be used as an antennae? Aside from circuit isolation, why are side mirrors and window frames and all the other similar systems mentioned above not used more often? Why did cars end up needing a separate bit of metal just for conducting radio signals?
Too many questions?
I'm just thinking how good an antennae the folding frame for the soft-top can be if properly isolated.
D O'Brien

JUST TO CLARIFY - the post dated 13th October at 16:13:40 - apparently from Marc , London and which begins by apologising for the use of "proper car" was not sent by me. I don't have a modern car and I'm not seduced by cruise control and the rest of it.

I think that the post might be from Bill, London and who made an innocent error in sending his post - or else someone is taking the piss although I can't for the life me think why.
Marc

Marc, twas I, deepest apologies, I usually use copy and paste to fill the boxes in, and I must have been under the influence at the time.

Sorry.
Bill

Mike MaGee:
JC Whitless does sell an after market, one-size-fits-all windshield antenna for those who boldly go....

The example of Nikola Tesla ought make anyone believe that there are endless possibilities for an antenna from misc parts on our cars. The trouble is identifying them, and then determining whether they are any better than the mast antennas used for decades now. I don't doubt that there is another way to skin the cat - I have a simple Terk amplified antenna for my FM receiver at home and frankly, it outperforms the beam antenna I used to have on my roof. Go figure. Good engineering and a better understanding of radio antenna design??
Bob Muenchausen

D

A number of years ago Dodge sold a small car made by Misubishi (I think). It used the trunk lid as the antenna, properly insulated of course. Apparently worked.

FWIW

Larry
Larry Hallanger

Jon/Canada- You out there with reference to the winshield wire maker or url?
vem myers

"Can anyone suggest a solution, I would prefer not to fit an external aerial as it spoils the clean appearance of the mk 1 GT."

Brian, FWIW, on my GT, I installed an antenna at the side of the windshield, mounted to the windshield surround. I had to drill three holes in the surround, one about 1/2" and the other two just big enough for sheet metal screws, and run the antenna lead through the 1/2" hole into the interior. It took about 30 minutes to install. It works well, and it is barely visible unless I extend it for better reception in rural areas. Very few people even notice it until I point it out to them.

I bought an antenna especially made to mount this way at a local Pep Boys, but they can be found at many other stores as well for around $10 or so, maybe a bit more.

I know I haven't described it very well, so I'll try to expand. The antenna is the same as any fender mounted antenna, but it lays against the windshield surround, about 1/2 inch from it, and runs parallel to the side of the windshield. The bottom of the antenna is fastened to a plastic clip that screws to the body, and there is a smaller plastic clip near the top that also mounts to the body to hold the antenna in place.

My car is in Michigan right now, or I'd take a picture of it for you.

Hope this helps.
Dan Masters

I have a GT with no radio at all; but I have often thought that, if I installed a radio, I would mount a power antenna in the rear fender. There is a nice sized space behind the wheel arch and the antenna could actually be mounted just to the inside of the bead on the top of the fender. This would be nearly unnoticable and would work well.
John Hubbard

The windshield mounted AM/FM antenna that I am referring to is model # WEA-200 made by Harada Industries of America,Southfield,MI
48034 and Canadian division, Harada Antenna Ltd,Whitby,Ontario L1N 8X8. I have ,as mentioned, great success with this unit.
Jon Rosenthall

Hi all.

A radio wave is rather like ripples in a pond.
In order to extract a signal from the waves you need to have a reception device which is exposed to the waves AND has a 'reference'.
Back at the pond, if you float a twig on the pond, it will move up and down with the waves, but it has no reference.
If you stick a twig in the mud at the side of the pond it won't move and won't extract any energy.
Now imagine a long twig which is stuck in the mud at one end, but the other end is exposed to the ripples and bends with them.. we are now extracting energy.

Sooooo...

1) It is better to have an antenna sticking up into the air and exposed to the waves.

2) The antenna needs to be a reasonable length, preferably resonant like the ruler that you used to twang on the edge of your school desk. (impractical for am bands).

3) A monopole antenna must have a reference, in our case usually the car bodywork. Car bodywork is usually all connected together, so can't be used as an antenna.

4) A heated rear window element is connected to chassis at one end, and connected to the wiring loom at the other, making it useless UNLESS....

5) It is possible to isolate the heated rear window element AT RADIO FREQUENCIES while still allowing the dc current needed to make the HRW heat. This would have to be done with inductors which present a high impedance to RF, but a low impedance to dc, not forgetting that the dc current for a HRW is quite high.
It is also necessary to connect the radio to the antenna via a dc blocking device, eg a capacitor.
A HRW is not in a good position to intercept the waves, so won't work as well as a conventional antenna.

HTH.. Don
Don

Over the years, an antenna I have wondered about has been one as have been used on several Hondas I am aware of and several other makes. The antenna configuration utilizes the "wasted" space of the interior of the "A" pillar to house it when retracted. This antenna layout is less conspicuous and it may be possible to utilize one from an existing car, like a Honda, etc. I have never gotten past the "wonder which one would work" stage, but a trip through a junqueyard might inspire someone. FWLIW
Bob Muenchausen

Don Cornwall, who seems to be quite knowledgable, wrote:

"2) The antenna needs to be a reasonable length, preferably resonant like the ruler that you used to twang on the edge of your school desk. (impractical for am bands)."

In theory, the antenna needs to be 1/4 as long as the wavelength of the signal you want to receive. For FM, this works out to about 31". For AM, as Don wrote, the length works out to be way too long to be practical.

That's theory. In practice? Well, how many of you remember when we got TV reception on a pair of rabbit ears? Remember how, when you wanted to pick up a distant station, you stood with one hand on the rabbit ears, one hand over your head, one leg in the air and your toungue hanging out? Then somebody came along and moved a table lamp and you had to find a new position to get it to work again?

In isolation, antennas work as theory predicts. In the real world, with all the interference, they sometimes don't. In my antenna course in engineering college, my instructor pointed out how antennas were designed in the real world -- you design them according to theory, and then you went into the field and started playing with your design until it worked.

None of the above adds any value to this thread, but I thought it might be amusing to read.
Dan Masters

Hi all.

Some cars (eg unmarked police cars) have covert two-way VHF / UHF radio aerials fitted.

One popular position for such an aerial is beneath one of the sills. It must be spaced away from the sill as far as possible while having sufficient ground clearance.. yet another reason for having an RB :-P...

Don
Don

This thread was discussed between 06/10/2003 and 18/10/2003

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