Mag Mount antenna for FM broadcast

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toshiba1
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Mag Mount antenna for FM broadcast

Post by toshiba1 » Thu Aug 04, 2022 6:06 pm

Is there any such thing that could be used and utilized in this way to broadcast on FM 88 - 108 from a vehicle?

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Re: Mag Mount antenna for FM broadcast

Post by toshiba1 » Thu Aug 04, 2022 6:39 pm

Its probably a laughable idea, but thought i'd ask.

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Electronically
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Re: Mag Mount antenna for FM broadcast

Post by Electronically » Thu Aug 04, 2022 9:26 pm

Yup ,you can use the K33 Car Clip Antenna Quality Assurance 88-108MHz 2.15 dBi Gain TNC Connector for Radio Broadcast Fm Transmitter,however its not a magmount ,but you just simply clip it to your car and tighten up same thing,

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Re: Mag Mount antenna for FM broadcast

Post by Albert H » Fri Aug 05, 2022 4:42 am

Yes - as long as the vehicle has a metal body!

I used a base-loaded 7/8th-wave mag-mounted aerial for some of the earliest test transmissions from my station in the Hollywood Hills back in 1980. We tried a more traditional 1/4-wave job first, but the high radiation angle combined with the high site meant that the signal largely went over the top of the target area below, rather than down into it. The bigger aerial had a lower radiation angle, and worked rather better.

Our next aerials (also fed from a rig in a car) were stacked "H"-types (reflector and radiator - the simplest Yagi), aimed down into the city. These were installed up a tree! We subsequently went to a four stack of three-element Yagis, and used those for the rest of the life of the station. The forward gain of the aerials, and the combination of stacked Yagis made for a cracking signal into the target area, despite the use of as little as 40 Watts from the early rigs.

Later on, we ran as much as 300 W into the aerial array, but only after we'd installed mains power to the tree!
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Re: Mag Mount antenna for FM broadcast

Post by reverend » Fri Aug 05, 2022 8:38 am

Just buy an amateur radio 4m/70MHz quarter wave magmount (on fleaBay for about £25) and then cut the whip down to size depending on the frequency you intend to operate on. Works a treat!
if it ain't broke, keep tweaking

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Re: Mag Mount antenna for FM broadcast

Post by teckniqs » Sat Aug 06, 2022 7:05 am

reverend wrote:
Fri Aug 05, 2022 8:38 am
Just buy an amateur radio 4m/70MHz quarter wave magmount (on fleaBay for about £25) and then cut the whip down to size depending on the frequency you intend to operate on. Works a treat!
Or a low band VHF taxi whip (66-88MHz).

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Re: Mag Mount antenna for FM broadcast

Post by Albert H » Sun Aug 07, 2022 2:39 am

You used to be able to get the taxi aerials from Moonraker for about £18
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Re: Mag Mount antenna for FM broadcast

Post by toshiba1 » Sun Aug 07, 2022 5:21 pm

Thank you, I enjoy reading of the endeavors of the past, and amazed at some of the very inventive ideas that you people have come up with. To have choice of tower blocks are far and few between and to be able to try things out in such a country as the USA with mountain terrain sounds like a dream.

Would i be right or wrong thinking the car acts as a ground plane hence better radiation pattern with these type of antenna? What if it was just a metal platform would the antenna work in the same way? I noticed the K33 antenna gave 6mhz bandwidth, is that what it will give you either side of the FM band? As that sounds quite tight? I noticed in the US the stations were squeezed next to each other, unlike here where you can go 25/35mhz either side of the spectrum. ( Well maybe not in the big cities anymore?)

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Re: Mag Mount antenna for FM broadcast

Post by Albert H » Mon Aug 08, 2022 2:15 am

I've used mag-mounts on top of metal water tanks with good results!.

You're right - the roof of the car provides the groundplane for the vertical radiator to operate against.

Many manufacturers claim that their aerials give quite wide bandwidth. This may be so for reception, but it's always best to have exactly the right element length for your frequency of choice. I have a mag-mount here somewhere with a short vertical whip and a telescopic section above, so that it can be tweaked for the frequency. This was convenient for festivals and similar events when I wasn't certain which frequency I could get away with....!
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Re: Mag Mount antenna for FM broadcast

Post by Persona Non Grata » Mon Aug 08, 2022 10:25 am

While the possibility of a bust is reduced when operating mobile bear in mind that OFCOM can seize vehicles so I wouldn't be doing it from my Bentley or anything.

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Re: Mag Mount antenna for FM broadcast

Post by toshiba1 » Tue Aug 09, 2022 5:31 pm

Persona Non Grata wrote:
Mon Aug 08, 2022 10:25 am
While the possibility of a bust is reduced when operating mobile bear in mind that OFCOM can seize vehicles so I wouldn't be doing it from my Bentley or anything.
A Bentley? If only... The above did make me chuckle though.

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Re: Mag Mount antenna for FM broadcast

Post by toshiba1 » Tue Aug 09, 2022 5:34 pm

Thanks for the info to all by the way.

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Re: Mag Mount antenna for FM broadcast

Post by toshiba1 » Sat Aug 13, 2022 2:09 pm

Would this do the trick? How correct or incorrect would i be if as an example for frequency of 88mhz, using online calculator i'd need to cut the whip down to 32 inches? And would i need a choke near to the feed end and a balun?

https://www.ebay.co.uk/itm/221270549044 ... BMtNiD89Jg

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Re: Mag Mount antenna for FM broadcast

Post by toshiba1 » Sun Aug 14, 2022 7:00 am

choke/balun... as i understand.

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