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Old 17th May 2022, 2:26 pm   #21
paulsherwin
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Default Re: FM Radio Aerial Recommendations

If you have easy access to the loft, a homemade dipole is the obvious way to go. You just need a length of garden cane or a long stick and 2 75cm lengths of wire. Join the wires to the inner and outer of a length of coax and tape the wires to the cane. You will need to experiment with the best location and alignment - an FM tuner with a signal strength meter makes this easy.

While not as good as a proper external aerial high up on a chimney, this will be *much* more effective than any tabletop indoor aerial, whether amplified or not.
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Old 17th May 2022, 2:52 pm   #22
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Default Re: FM Radio Aerial Recommendations

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Originally Posted by DMcMahon View Post
Thank you Paul.

Any idea if the integral FM aerial on my JVC JR-S201L AM/FM Receiver as can be seen in the attached photo, is likely to have any amplification and would an amplified telescopic dipole aerial be likely to provide stronger signal/better reception, once best/optimum position/alignment is determined.

David
Almost certainly no amplification for the following reason.

Amplifiers on indoor aerials are a waste of time, money, and electricity. An amplifier is designed to go at the start of a long run of coax, which an indoor aerial does not have, to preserve the signal to noise ratio.

All that happens with a noisy signal on an indoor aerial is louder noise.
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Old 17th May 2022, 2:56 pm   #23
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Default Re: FM Radio Aerial Recommendations

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Sorry Paul to be ignorant, where does the 3dB mismatch come from, are you saying that the coax connection even though it would plug into a coax connector on the radio, it is not 300 Ohms like the screw terminal connection ?

David
Coax connectors are 75Ω. See the picture in post 3.
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Old 17th May 2022, 3:37 pm   #24
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Default Re: FM Radio Aerial Recommendations

What about the second part of my original question, i.e. any good aerials that can do both FM and AM well in the same single aerial.

I guess the answer most likely is no, aerials such as ones called universal probably will not do a great job plus presumably would need 2 aerial cable connections.

David
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Old 17th May 2022, 4:09 pm   #25
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Default Re: FM Radio Aerial Recommendations

No. They function in different ways. They can 'work', but an FM aerial will be very suboptimal for lower frequencies, and a long MW aerial will be poor for VHF.

Of course, strange things can happen with radio reception, and it does no harm to experiment.
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Old 17th May 2022, 4:48 pm   #26
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Default Re: FM Radio Aerial Recommendations

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Originally Posted by paulsherwin View Post
If you have easy access to the loft, a homemade dipole is the obvious way to go. You just need a length of garden cane or a long stick and 2 75cm lengths of wire. Join the wires to the inner and outer of a length of coax and tape the wires to the cane. You will need to experiment with the best location and alignment - an FM tuner with a signal strength meter makes this easy.

While not as good as a proper external aerial high up on a chimney, this will be *much* more effective than any tabletop indoor aerial, whether amplified or not.
I made a similar FM loft dipole by splitting a coax to give the 2 x required lengths obtained a google searched FM dipole calculator - setting it to mid freq between 88 & 108 meg. I hung the dipole vertically to make it onmi directional. Reception was fine excepting Radio 2 because I live on the Eastern side of Leicestershire too far from the transmitter. A previous one worked a treat (even with Radio 2). This was slant polarised between an outside chimney & gutter. Sadly the wind eventually took it's toll & snapped one leg of the dipole.

For MW reception I recall a lot of 80's radios came with a separate wirewound frame aeriel which could be rotated for best reception.

Rog
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Old 17th May 2022, 7:25 pm   #27
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Default Re: FM Radio Aerial Recommendations

The traditional aerial for AM used to be the 'long wire' aerial.
However they pick up a lot of switch-mode noise and some radio stations can be smothered in noise.

Frame aerials and ferrite rods can be quite good.

A steerable tuned loop aerial is probably the best for signal to noise ratio.
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Old 17th May 2022, 9:06 pm   #28
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Default Re: FM Radio Aerial Recommendations

The polar diagram of a horizontal dipole has two very broad lobes either side of two very deep end-on nulls. Unlike directional multi-element Yagis, the broad lobes mean there is little need for orienting for maximum strength. Instead, the nulls can be used to reject unwanted co-channel and adjacent channel interference.

In the 1970's when I had just bought my first house and couldn't afford a TV, I made a FM dipole from two lengths of 15mm copper pipe spaced apart using a short piece of oval plastic conduit, and mounted it on a home-made rotator. This was before the FM band filled up with commercial and local radio stations, and I could use the deep nulls to tune out local stations in order to better receive French FM stations clearly. My house was in the north - eastern suburbs of London, and the continental signals were usually strong enough for stereo reception. I used to get Radio Oxford loud and clear too.

I still use the home-made dipole but not the rotator.

Last edited by emeritus; 17th May 2022 at 9:12 pm. Reason: typos
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Old 18th May 2022, 12:00 am   #29
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Default Re: FM Radio Aerial Recommendations

Especially for stereo, there is no substitute for a roof mounted FM aerial. A three-element Antiference is a good place to start. And get a professional to put it up. Besides pointing it in the right direction, he should know how to avoid putting a foot through your roof.
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Old 18th May 2022, 9:44 am   #30
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Default Re: FM Radio Aerial Recommendations

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Originally Posted by Roger Ramjet View Post

I made a similar FM loft dipole by splitting a coax to give the 2 x required lengths obtained a google searched FM dipole calculator - setting it to mid freq between 88 & 108 meg. I hung the dipole vertically to make it onmi directional. Reception was fine excepting Radio 2 because I live on the Eastern side of Leicestershire too far from the transmitter. A previous one worked a treat (even with Radio 2). This was slant polarised between an outside chimney & gutter. Sadly the wind eventually took it's toll & snapped one leg of the dipole.

For MW reception I recall a lot of 80's radios came with a separate wirewound frame aeriel which could be rotated for best reception.

Rog
Aren't most FM transmissions in Britain horizontally polarised? If those that you want are, a vertical dipole won't be very good.
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Old 18th May 2022, 10:10 am   #31
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Default Re: FM Radio Aerial Recommendations

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Quote:
Originally Posted by Roger Ramjet View Post

Rog
Aren't most FM transmissions in Britain horizontally polarised? If those that you want are, a vertical dipole won't be very good.
This use to be the case until the 1980's. Most FM transmissions since then use mixed polarisation with some relays and low powered FM transmitters using only vertical polarisation
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Old 18th May 2022, 10:10 am   #32
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Default Re: FM Radio Aerial Recommendations

Slant or mixed polarisation has been standard since the 80s. This was done to better support car radios and portables.
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Old 18th May 2022, 10:39 am   #33
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Default Re: FM Radio Aerial Recommendations

Hi David

Worthing eh? lovely part of the world for holidays and living.

As with everything though, there is a drawback. The area is between 7 and 180 metres above sea level with Burgess Hill not only stopping the invading masses from the North but the radio signals from there as well.

The vertical/horizontal polarisation of the aerial was once important but not today. Following FM car radio days, slant polarisation is used.

Personally, I would list the radio stations you want to receive and map where they are. There are, for some stations, field signal maps of their service area.

The recommendation to use a 3 element always strikes me as a good starting point.

Once upon a time, looking at the roof tops to see what your neighbour uses was a good indicator but, as with 405 aerials, you may be hard pressed to find one!!

Using an indoor/telescopic aerial,even where I live, is problematic in some rooms. Although the house is within spitting distance of Crystal Palace and Wrotham should be able light a bulb, my neighbours houses, all 20 of them, are in the way!!

Hope this all helps.

PS My son has home in Poole. Some aerials point out to sea to the Isle of Wright!! Fill in transmitting masts in Poole not only have limited stations but just don't work everywhere.

Good luck.

Chris

Last edited by simpsons; 18th May 2022 at 11:00 am.
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Old 18th May 2022, 11:01 am   #34
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Default Re: FM Radio Aerial Recommendations

It's certainly true that Sussex is notorious for reception problems, both radio and TV.
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Old 18th May 2022, 7:13 pm   #35
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Default Re: FM Radio Aerial Recommendations

The first BBC FM transmissions in the 50s were horizontally-polarised; they expected listeners [invariably in a house, the idea of portable/in-car FM radios still being beyond their imagining] to use an outdoor directional antenna, again horizontally-polarised.

Come the 1970s and commercial FM stations, they went for 'slant' polarisation, because it worked well for both the listeners on portable/car radios with predominantly vertical whip antennas, and the people who had paid over-the-odds a decade back for a horizontally-polarised multi-element FM beam-antenna.

These days, if you're not sure just what you can receive at your location, I'd experiment with a "bamboo-pole" dipole as mentioned upthread. Mount it vertically, and use 75-Ohm coax to connect it to the antenna-socket of your radio. It will be omni-directional and so give you a good insight to the stations you can receive in your area.

Then you can maybe move on to something with directionality, aimed at the stations you want to listen to.

[Currently I'm listening to Greatest Hits Radio around 107MHz using a vertically-polarised dipole made from 15mm water-pipe and optimised for 104MHz; I've got a couple of coaxial 'stubs' cut to take out the otherwise-intrusive BBC-National stuff between 88 and 95MHz].
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Old 18th May 2022, 8:00 pm   #36
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Default Re: FM Radio Aerial Recommendations

Many thanks to everybody for the various interesting information and useful suggestions, I now have a much better understanding of FM aerials.

I certainly will try some of the suggestions out and report back, may take some time as time is limited.

David
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Old 23rd May 2022, 3:14 am   #37
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Default Re: FM Radio Aerial Recommendations

I had a look at the downloaded instructions for a Heathkit AR14 stereo tuner/amp that I built in the 60's. It says words to the effect that you connect a 300ohm line to each screw of the antenna connector but if you have 75 ohm coax then you connect the centre conductor to one screw and the braid to an adjacent chassis screw.
As you see from the circuit the antenna transformer has a centre tap to ground, so therefore if the whole transformer is 300ohm impedance, then half the turns is 75ohms. Makes sense to me.
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Old 2nd Aug 2022, 10:03 am   #38
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Default Re: FM Radio Aerial Recommendations

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Originally Posted by simpsons View Post

Personally, I would list the radio stations you want to receive and map where they are. There are, for some stations, field signal maps of their service area.

Chris
I actually hardly ever listen to the radio at home, but do intend to when can find more time

At home when I am struggling to find something worth watching on TV, I will sometimes scan through the numerous radio stations available through Virgin Media on my TV.

When I am out in the car I normally listen to either BBC Radio Four or Planet Rock, both on DAB.

Not yet found the time to try different types of FM aerial.

David
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Old 2nd Aug 2022, 10:02 pm   #39
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Default Re: FM Radio Aerial Recommendations

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Indoor aerials are always a last resort, with inherent problems and limitations.

Your best approach is to go for a cheap telescopic amplified dipole, or make one yourself. The amp is usually a simple one transistor affair, giving about 10-16dB of gain. There's no point in going for anything more exotic, as the indoor limitations will still be there.

You will need to experiment with different positions and alignments.
An amplifier on an indoor aerial is a waste of time, money, and electricity. An amp is designed to go at the start of a long run of coax to overcome the cable loss which you don’t have on an indoor aerial.

All that happens is you get louder noise, but not improve the signal to noise ratio.
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Old 3rd Aug 2022, 8:59 pm   #40
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Default Re: FM Radio Aerial Recommendations

I have used one of these https://cpc.farnell.com/antiference/...st=fm%20aerial for some years in the loft. Stonking signal from Wrotham and all the locals and good signals from some not-so-locals like Essex and Oxford. Whatever you do, avoid one of those awful 'halo's...I was given a new one prior to using the dipole and I'm sure a piece of wet string would have worked better!
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