FM Aerial

[Munroast]

I choose to listen to a radio station some distance from where I live. Most of the time reception is good enough, however from time to time reception is poor. What should be my next move to improve overall reception?

Current situation ... I have an Omni Direction aerial (one of those round things) mounted as high inside the roof space as possible.
When tuned into a radio station within my area I get a signal strength of 60db, when tuned into the distant station I get between 25db and 35db

How much benefit will i get from mounting the omni aerial outdoors.
If i fitted a directional aerial would I loose quality on my local stations.
Not really wanting an outdoor aerial, so would there be much benefit from a directional aerial in the loft space.


Thoughts?

 

[ChrisFrost]

Omni's are good compared to the bit of wire supplied in the box for a hifi or tuner, but they aren't a good solution for serious listening. Because the antenna is curved there is very little metal actually facing the transmitter.

The best solution is a proper FM aerial directed at the distant FM transmitter. It will pull in loads more signal and give far better results.

Keep the omni for general listening. Have the better aerial on a separate wire. Switch the plugs when changing stations.... or buy a rotor so the good aerial can be pointed in different directions for the various FM transmitters.

 

[Munroast]

Would a "Directional FM aerial" mounted within the roof space be better than an "Omni" mounted on top of the roof. re no wood and slates to go through

Not going to go to the bother/expense of switching plugs/rotor device. So, if I am getting 60db signal from local transmitter with the Omni, what signal could I expect from a directional pointed the wrong way?

 

[Wooster]

Would a "Directional FM Ariel" mounted within the roof space be better than an "Omni" mounted on top of the roof. re no wood and slates to go through

Not going to go to the bother/expense of switching plugs/rotor device. So, if I am getting 60db signal from local transmitter with the Omni, what signal could I expect from a directional pointed the wrong way?

A directional aerial pointed the wrong way? Sorry - don't follow you train of thought. Very roughly speaking: If a standard dipole has a gain of 1, a dipole with a reflector will have a gain of 2. Add a 'director' and the gain is 3. Add a second director and the gain will be 4. By comparison a curved non-directional aerial has a gain of minus (-) half. (-0.5)
So a 4 element directional aerial will have a gain 4 times that of a curved dipole.
A directional aerial within the roof vs a 'omni' outside? Too complex to answer. But subtract 50% if the signal is going through a wall - even more if it's focused through wet tiles. Signal (probably ) doubles for every 10ft in height.

Best solution? A 4 element aerial on a 6 ft pole on your chimney.

 

[Munroast]

A directional aerial pointed the wrong way? Sorry - don't follow you train of thought.

Does sound a bit thick ... To explain, I regularly tune into a radio station that is about 60 mile to my SouthEast. Reception is ok and occasionally on the poor side of OK. If I was to use a directional aerial pointed to the SE, how would this effect other stations that I receive from my local transmitter that is to my west.

I.E. the directional aerial will be pointed in the wrong direction for my local transmitter. In this circumstance will the signal be as good as the current omni directional that gives excellent reception.

And as said above I am not interested in switch cables every time i change stations or installing (probably expensive) motors to automatically rotate aerial

- even more if it's focused through wet tiles.

Interesting.... reception this past few days has been a little hissy, fairly damp this past few days with continuously wet slates.

 

[ChrisFrost]

TBH if you can't be bothered swapping a plug from one aerial to the other then you really shouldn't bother with any sort of directional aerial. Just get an omni put on a pole on the chimney stack and be done with it.

 

[Wooster]

A directional aerial pointed the wrong way? Sorry - don't follow you train of thought.

Does sound a bit thick ... To explain, I regularly tune into a radio station that is about 60 mile to my SouthEast. Reception is ok and occasionally on the poor side of OK. If I was to use a directional aerial pointed to the SE, how would this effect other stations that I receive from my local transmitter that is to my west.

I.E. the directional aerial will be pointed in the wrong direction for my local transmitter. In this circumstance will the signal be as good as the current omni directional that gives excellent reception.

And as said above I am not interested in switch cables every time i change stations or installing (probably expensive) motors to automatically rotate aerial

- even more if it's focused through wet tiles.

Interesting.... reception this past few days has been a little hissy, fairly damp this past few days with continuously wet slates.

There is no real way of telling - without installing the aerial/s. It depends totally on how close the 'local' transmitter is and what power it has.

My 'local' is only 1 mile away (I can see the transmitter) so it doesn't matter what way my aerial is pointing. It's such a thumping signal...

One thought: An aerial diplexer / splitter. Essentially connecting two FM aerials to one downlead - which leads to your radio. Typically diplexers are used to run a TV and an FM aerial down one lead - but you can use them for two FM aerials. If you could point each aerial at each transmitter, and you have one lead connected to your radio. Two minutes on Google shows this sort of thing:

http://www.aerialsuperstore.co.uk/f-splitter-2-way-174-p.asp

Might be a solution....

And - slates are the worst things for stopping aerial signals - far worse than concrete / clay tiles

 

[ericmark]

I did some experiments with two omi-directional aerials one what we refer to as a halo which was horizontal polarised the other a 7/8 whip vertical polarised with an aerial switch in the car so I could switch between the two.

The halo has a minus db gain compared with dipole and the whip a plus db gain so around 6 db between aerials and the guy I was doing experiment with was transmitting on a horizontal polarised yargi beam.

We were using side band on 2 meter band around 144Mhz a little higher than domestic radio but results should still be valid.

What I found was when close there was a marked improvement using the halo but as the distance increased so the whip first equalled then bettered the halo.

Started Sizewell Power station break even point Cambridge so I would guess around 45 miles as crow flies.

You say omi-directional aerial what type vertical or horizontal and is this matched to transmitter? You also say distance transmitter how distance is the distance. Personally I don't consider anything closer than 100 miles as a DX station and would only exchange QSL cards for special event stations if closer than 100 miles.

Remember I was only transmitting with 25W when as commercial transmitters will use at least 10 times that power.