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uk.tech.digital-tv (Digital TV - General) (uk.tech.digital-tv) Discussion of all matters technical in origin related to the reception of digital television transmissions, be they via satellite, terrestrial or cable. Advertising is forbidden, with no exceptions.

OT - FM aerial



 
 
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  #1  
Old December 12th 06, 02:40 PM posted to uk.tech.digital-tv
Tim..
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Posts: 16
Default OT - FM aerial

Any groups for talking about FM style radio aerials?

Want to fit an external one for my DAB / Analogue tuner...

Tim..


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  #2  
Old December 12th 06, 04:24 PM posted to uk.tech.digital-tv
Paul D.Smith
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Posts: 1,070
Default OT - FM aerial

I got lots of good advice from here although I was putting up a DTT aerial
at the same time.

The basic advice was "don't use the circular ones, they're rubbish". I
eventually put up a simple verticle dipole (antiference I think) but then
I'm in a good reception area and I get a large number of FM channels (far
more than I expected!).

Paul DS.


  #3  
Old December 12th 06, 05:35 PM posted to uk.tech.digital-tv
Chris
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Posts: 8
Default OT - FM aerial

OOn Tue, 12 Dec 2006 16:24:54 -0000, "Paul D.Smith"
wrote:

The basic advice was "don't use the circular ones, they're rubbish". I
eventually put up a simple verticle dipole (antiference I think) but then


I agree with this but a lot depends on where you live. It probably
makes sense to put up an aerial that is OK for FM and DAB if that
proves possible. See this URL for some general advice on DAB:
http://www.wohnort.org/DAB/aerials.html

This is a link to an specialist aerial wholesaler that I have used who
also sells retail including mail order: http://www.scantec.org.uk/
  #4  
Old December 12th 06, 06:06 PM posted to uk.tech.digital-tv
Tim..
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Posts: 16
Default OT - FM aerial


"Chris" wrote in message
...
OOn Tue, 12 Dec 2006 16:24:54 -0000, "Paul D.Smith"
wrote:

The basic advice was "don't use the circular ones, they're rubbish". I
eventually put up a simple verticle dipole (antiference I think) but then


I agree with this but a lot depends on where you live. It probably
makes sense to put up an aerial that is OK for FM and DAB if that
proves possible. See this URL for some general advice on DAB:
http://www.wohnort.org/DAB/aerials.html

This is a link to an specialist aerial wholesaler that I have used who
also sells retail including mail order: http://www.scantec.org.uk/



Thanks for the info so far so good...

The next question is.... which direction do I point it in?! (assuming rod
type)

Same as TV (sutton coldfield- but about 50miles away - there are closer
analogue TX's but none which are outputting digital TV..

Tim..


  #5  
Old December 12th 06, 07:03 PM posted to uk.tech.digital-tv
charles
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Posts: 4,016
Default OT - FM aerial

In article ,
Tim.. wrote:


The next question is.... which direction do I point it in?! (assuming rod
type)


We have to know where you are to answer that one.

Same as TV (sutton coldfield- but about 50miles away


quite possibly

--
From KT24 - in "Leafy Surrey"

Using a RISC OS computer running v5.11

  #6  
Old December 12th 06, 07:09 PM posted to uk.tech.digital-tv
Nigel Cliffe
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Posts: 68
Default OT - FM aerial

Tim.. wrote:
Thanks for the info so far so good...

The next question is.... which direction do I point it in?! (assuming
rod type)



A simple rod dipole is just stood vertically (vertical polarisation). There
isn't any "direction" about it.


If its a bigger aerial, then you need to know where your FM transmitter is
located. Then point the aerial at the transmitter.
This may help:
http://www.bbc.co.uk/reception/trans...ns/index.shtml


Note that the BBC's list of DAB transmitters may not be the same as the
commercial radio set.



- Nigel

--
Nigel Cliffe,
Webmaster at http://www.2mm.org.uk/


  #7  
Old December 12th 06, 07:23 PM posted to uk.tech.digital-tv
Mark Carver
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Posts: 7,633
Default OT - FM aerial

Tim.. wrote:

The next question is.... which direction do I point it in?! (assuming rod
type)


If it's a single vertical rod, you don't ! It will have omni-directional
response, except for the 'mast shadow' formed by its mounting.

See this photo from Bill Wright's website:-

http://www.wrightsaerials.tv/025%20s...TC18A%20H.html

A DAB aerial looks exactly the same, only the rods are shorter. As DAB uses
the same frequency from each transmitter that carries a particular mux, you
can capitalise on this because the aerial will pick up any suitable
transmitters in range. All UK DAB transmissions are vertically polarised, so
aerials must be mounted vertically. FM transmissions with only one or two
exceptions (and none in your area) are either mixed polarisation or
vertical. So again a single vertical rod FM aerial might be fine. However
there are two potential problems.

1: Multipath distortion, this is FM's equivalent of ghosting on analogue TV.
Because the single rod is omni directional, it will pick up any reflected
signals too. Whereas DAB reception is not generally affected, and in most
cases actually takes advantage to enhance the signal, on analogue systems it
leads to distortion and other spurious noises.

2: If you are trying to receive distant signals then a vertical rod (or
dipole to give it its correct term) might not have enough gain to receive
them properly. In this case you need a directional aerial, called a yagi.
This will have two or more elements. A high gain FM yagi will have about six.

If you can state which stations, FM and DAB, you want to receive, and your
location (nearest town etc) we can advise you better of your options.


--
Mark
Please replace invalid and invalid with gmx and net to reply.
  #8  
Old December 12th 06, 07:25 PM posted to uk.tech.digital-tv
john
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Posts: 3
Default OT - FM aerial


"Nigel Cliffe" wrote in message
...
Tim.. wrote:
Thanks for the info so far so good...

The next question is.... which direction do I point it in?! (assuming
rod type)



A simple rod dipole is just stood vertically (vertical polarisation).
There isn't any "direction" about it.


You can make it more directional by spacing it at a correct distance from a
mast - so the mast acts as a reflector along the full length of the dipole.
That will give a heart shaped pattern known as cardioid.
Don't buy a cheap aerial from the likes of B&Q as the cable is attached
around the top of a self tapping screw which goes through the plastic and
element!
It's a poor design as water gets inside and corrodes the connections. Then
it will run down your coax. Give it six months and your reception will be
poor.

Use a decent dipole, cover the end of the coax inside the connection point
in self amalgamating tape were you split the inner core from the braid, then
waterproof with grease after making the connections. Centre to the element
pointing up and braid pointing down. Tape the connection box up with self
amalgalamting tape too - you will not have any problmes with it for some
years.

You can use the same aerial to pick up DAB, but don't expect it to pick up
stations from the other end of the country!

Don't forget good quality coax such as CT100 or equivalent.


  #9  
Old December 12th 06, 07:41 PM posted to uk.tech.digital-tv
charles
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Posts: 4,016
Default OT - FM aerial

In article ,
john wrote:


Use a decent dipole, cover the end of the coax inside the connection
point in self amalgamating tape were you split the inner core from the
braid, then waterproof with grease after making the connections. Centre
to the element pointing up and braid pointing down.


That doesn't sound like a decent dipole - no balun :-(

--
From KT24 - in "Leafy Surrey"

Using a RISC OS computer running v5.11

  #10  
Old December 12th 06, 08:14 PM posted to uk.tech.digital-tv
Max Demian
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Posts: 3,970
Default OT - FM aerial

"Nigel Cliffe" wrote in message
...
Tim.. wrote:
Thanks for the info so far so good...

The next question is.... which direction do I point it in?! (assuming
rod type)


A simple rod dipole is just stood vertically (vertical polarisation).
There isn't any "direction" about it.


Isn't VHF/FM broadcast with horizontal polarisation any more?

--
Max Demian


 




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