[OT] Best FM aerial?

David W.E. Roberts said the following on 09/01/2005 17:23:

Aha!
http://forum.digitalspy.co.uk/board/...3&page=2&pp=25
says "Maplin sell them for 15-25 quid. alternatively, get yourself down to
B&Q and get a band II FM dipole for a tenner, borrow someone's hacksaw and
cut each length to around 66cm, re-assemble and voila - you have a DAB
dipole!"
which implies that B&Q do supply dipoles :-)


What ever Texas Homecare are called now (Homebase?) sell Dipoles too

I got my dipole from Maplin, alas i can't use it in my bedroom so make
do with the communal TV aerial (thats not needed since Saga joined NOW
Notts).

Kev

On Sun, 9 Jan 2005 18:43:33 -0000, David W.E. Roberts
wrote:


Thanks - will go for the dipole first.

I am in Felixstowe, Suffolk. IP11 postcode


A dipole will suit you fine. Your local BBC transmitter is Manningtree -
you can almost see it from Felixstowe.

- Arthur

Hello,

Please do not even consider a HALO ! A horizontally polarised folded dipole
bent into a circular shape with a MINUS figure for gain - so it will reduce
signal strength compared to a dipole.

If it's for normal use then get a VHF 88-108MHz dipole kit from B&Q for
example. Just make sure you mount it so that the centre conductor of the
coaxial cable is connected to the element sticking up in the air.
A lot of people can't even get that bit right and put them upside down.

If it's for indoor use, get a small junction box and two bits of wire about
70cm long, just hang it in the loft for local stations. If it's for a
specific station a fair distance away, you might need to buy a beam.

"David W.E. Roberts" wrote in message
...
I know it is not for a Digital TV,but...

...is there a better FM aerial than one of the 'halo' ones that at least
50%
of people seem to have?

I have also seen ones that look like really old (1950s) TV aerials which I
presume are for FM.

TIA

Dave R

--

"David W.E. Roberts" wrote in message
...
I know it is not for a Digital TV,but...

...is there a better FM aerial than one of the 'halo' ones that at least
50%
of people seem to have?

I have also seen ones that look like really old (1950s) TV aerials which I
presume are for FM.


Having searched the local TV shop (Hughes) and shed (Homebase) and come up
empty I travelled to B&Q.

The Masterplug dipole they sell is not a single aerial (one up, one down)
but a loop (like the slidy part of a trombone).

Each half is about 750mm long - one side (once assembled) is continuous (i.e
1.5m) and the other side feeds into the bracket where the co-ax attaches.

I am hopint this is a GOOD THING and that the issue with the 'hallo' aerial
is to do with it's bent shape and not the double aerial because what I seem
to have is a 'halo' aerial beforeit is bent into the donut shape.

Yours in hope

Dave R

P.S. I bought 2 (one for a neighbour) and of the two, one has a strange bit
of metal instead of a nut and so can't be assembled.
Realistically, it will be far cheaper to walk up to my local Homebase and
find a replacement nut than to drive to B&Q and back to exchange the aerial.
Still, 50% failure rate isn't that good.

"David W.E. Roberts" wrote in message
...

"David W.E. Roberts" wrote in message
...
I know it is not for a Digital TV,but...

...is there a better FM aerial than one of the 'halo' ones that at least
50%
of people seem to have?

I have also seen ones that look like really old (1950s) TV aerials which
I
presume are for FM.


Having searched the local TV shop (Hughes) and shed (Homebase) and come up
empty I travelled to B&Q.

The Masterplug dipole they sell is not a single aerial (one up, one down)
but a loop (like the slidy part of a trombone).

Each half is about 750mm long - one side (once assembled) is continuous
(i.e
1.5m) and the other side feeds into the bracket where the co-ax attaches.

I am sure that I have read somewhere that there should be a minimum distance
between the dipole and the mast.. However I can't find this at the moment.

The Masterplug aerial comes complete with a wall mount.
I have a bracket which will clamp the horizontal pole to my mast, but the
aerial will only be about 200mm away from the mast.
Is this O.K. or should I be looking to extend the horizontal mounting pole?

TIA

Dave R

"David W.E. Roberts" wrote:

I am sure that I have read somewhere that there should be a minimum distance
between the dipole and the mast.. However I can't find this at the moment.

Probably, the greater the better, but that puts a strain on the pole,
and a twisting strain when the wind blows. I do wonder if the pole
causes a hole in the FM reception in that direction. A halo might be
worse than a dipole in most directions, but I suspect that it's more
even directionally, and better at picking up signals from behind the
pole.

--
Dave Farrance

"David W.E. Roberts" wrote in message
...

"David W.E. Roberts" wrote in message
...
I know it is not for a Digital TV,but...

...is there a better FM aerial than one of the 'halo' ones that at least
50%
of people seem to have?

I have also seen ones that look like really old (1950s) TV aerials which
I
presume are for FM.


Having searched the local TV shop (Hughes) and shed (Homebase) and come up
empty I travelled to B&Q.

The Masterplug dipole they sell is not a single aerial (one up, one down)
but a loop (like the slidy part of a trombone).

Each half is about 750mm long - one side (once assembled) is continuous
(i.e
1.5m) and the other side feeds into the bracket where the co-ax attaches.

Yaargh!

The co-ax which comes with the kit is nice looking hefty black stuff (looks
like CF100).
However when stripped back there is virtually bugger all copper braid.
The copper coloured sheathing is silver on the inside, which suggests it is
not copper foil.
Fortunately I have a reel of SLx PF100 which seems to have real copper foil
and decent braiding, but why sell a kit with such crap cable?
[on the up side the brown cable I currently have installed, and was
considering replacing, has a really hefty copper braid so may be able to
stay]

I have connected this up temporarily ('F' plug into aerial and push plug at
other end) using the supplied cable and tried it in my radio in the kitchen.

Hand held, it performs worse than the 'halo' on the roof and seems best when
held horizontally.

I don't know how realistic a test this is but I am wondering how well it
will perform on the roof :-(

Now if will only stop raining....

Dave R

On Mon, 10 Jan 2005 14:07:03 -0000, David W.E. Roberts
wrote:

I am sure that I have read somewhere that there should be a minimum
distance between the dipole and the mast.. However I can't find this at
the moment.

The Masterplug aerial comes complete with a wall mount.
I have a bracket which will clamp the horizontal pole to my mast, but the
aerial will only be about 200mm away from the mast.
Is this O.K. or should I be looking to extend the horizontal mounting
pole?


To get true omni-directional reception with a vertical dipole you would
need to have it spaced at least a half-wave (i.e. the length of the dipole
aerial) away from the parallel pole. However you don't need omni because
you are on the coast!
Space it a quarter-wave (half the dipole length) away from the pole, but
make sure you put it on the *west* side of the pole. This will improve
the coverage to the west and put a notch to the east, so that you get less
interference from the continent during abnormal conditions.

Arthur

On Mon, 10 Jan 2005 15:19:57 -0000, "David W.E. Roberts"
wrote:


"David W.E. Roberts" wrote in message
...

"David W.E. Roberts" wrote in message
...
I know it is not for a Digital TV,but...

...is there a better FM aerial than one of the 'halo' ones that at least
50%
of people seem to have?

I have also seen ones that look like really old (1950s) TV aerials which
I
presume are for FM.


Having searched the local TV shop (Hughes) and shed (Homebase) and come up
empty I travelled to B&Q.

The Masterplug dipole they sell is not a single aerial (one up, one down)
but a loop (like the slidy part of a trombone).

Each half is about 750mm long - one side (once assembled) is continuous
(i.e
1.5m) and the other side feeds into the bracket where the co-ax attaches.

Yaargh!

The co-ax which comes with the kit is nice looking hefty black stuff (looks
like CF100).
However when stripped back there is virtually bugger all copper braid.
The copper coloured sheathing is silver on the inside, which suggests it is
not copper foil.
Fortunately I have a reel of SLx PF100 which seems to have real copper foil
and decent braiding, but why sell a kit with such crap cable?
[on the up side the brown cable I currently have installed, and was
considering replacing, has a really hefty copper braid so may be able to
stay]

I have connected this up temporarily ('F' plug into aerial and push plug at
other end) using the supplied cable and tried it in my radio in the kitchen.

Hand held, it performs worse than the 'halo' on the roof and seems best when
held horizontally.

I don't know how realistic a test this is but I am wondering how well it
will perform on the roof :-(

Now if will only stop raining....

Dave R


This test is not a realistic one at all. The reception on your roof
will be a lot stronger than your kitchen. I have a dipole, and
noticed a big difference between loft mounting & roof mounting.

BTW, a folded dipole is fine, as long as it's not bent into a halo ;-)

Marky P.

"Arthur" wrote in message
news
On Mon, 10 Jan 2005 14:07:03 -0000, David W.E. Roberts
wrote:

I am sure that I have read somewhere that there should be a minimum
distance between the dipole and the mast.. However I can't find this at
the moment.

The Masterplug aerial comes complete with a wall mount.
I have a bracket which will clamp the horizontal pole to my mast, but
the
aerial will only be about 200mm away from the mast.
Is this O.K. or should I be looking to extend the horizontal mounting
pole?


To get true omni-directional reception with a vertical dipole you would
need to have it spaced at least a half-wave (i.e. the length of the dipole
aerial) away from the parallel pole. However you don't need omni because
you are on the coast!
Space it a quarter-wave (half the dipole length) away from the pole, but
make sure you put it on the *west* side of the pole. This will improve
the coverage to the west and put a notch to the east, so that you get less
interference from the continent during abnormal conditions.

Arthur

Looks like I need to extend the pole :-(

Full length (with bracket in the middle) is 1530cms.
Presumably this is half wave (wavelength of 3m?).
[Aarrgh again - if the radio is Frequency Modulation then what is the
wavelength of the carrier which is having its frequency modulated?]
This would imply putting the dipole about 750cms away from the mast.
Which means I need about 500mm of extension.

Another thing.

With the 'trombone' shape, should the twin diploles be in line with the
signal source, or at right angles?
i.e. looking from the transmitter, should you see one dipole (with the other
hidden behind it) or see both dipoles as you would with a TV aerial?

Seems logical (working from TV aerials) that the oval should be at right
angles to the signal, but perhaps logic misleads.

Especially as this would require me to put the dipole on the north or south
of the mast given the shape of the mounting (which is at right angles to the
oval, not pointing through the middle).

Think I need a sit down and a medicinal :-)

Dave R