FM/DAB combo aerial diplexer?

peking97

Looking to purchase this combo antenna http://sat-planet.ie/saorview/aerials/radio_aerials/antiference-dab-fm-combo-aerial for my Denon M38DAB but would need a decent wallplate diplexer at the receiver. Can anyone recommend one please?...or indeed any other suggestions/comments welcome.

winston_1

Aerial gain is normally referenced to a dipole not an isotropic radiator.
So the FM section has a negative gain -2.2dB and the DAB section zero gain 0dB. So I would consider getting decent separate aerials with separate downleads, or even use siamese satellite cable which will be perfectly OK at DAB/FM frequencies.
Don't know of any DAB/FM diplexer wallplates either.

Sam Russell

What about the old NTL wall boxes labeled FM/TV - band II/ band III+band IV.

Have a few around the place.

peking97

Sam Russell wrote: »

What about the old NTL wall boxes labeled FM/TV - band II/ band III+band IV.

Have a few around the place.

Not famliar with those. Have they got Band II and Band III on separate outputs?

Sam Russell

peking97 wrote: »

Not famliar with those. Have they got Band II and Band III on separate outputs?

I believe so. They are designed for separating FM from the analogue TV signal, which is band III + IV. FM would then be sent to the HiFi, and the TV signal to the aerial input of the TV. I know they worked, but not sure how well.

coylemj

The 'FM' port on the NTL/UPC/VM wall box give you about 20 FM stations, including the main Irish stations (RTE and a few Dublin indies), BBC1-5, WRN and a few others. The frequencies are usually different from the original broadcast, especially with the Irish stations. As the source is a shielded co-ax cable, all you'll get is what UPC decide to give you, nothing else. Station name (RDS) is supported.

The 'TV' port can supply TV and/or Broadband, Virgin Media supplies an external splitter if you have digital TV and a separate broadband router.

Sam Russell

The OP is feeding from a DAB aerial and an FM dipole so the NTL wall box should be fine. They clearly work for splitting out the FM radio from the Band III/IV TV signal.

coylemj

Sam Russell wrote: »

The OP is feeding from a DAB aerial and an FM dipole so the NTL wall box should be fine. They clearly work for splitting out the FM radio from the Band III/IV TV signal.

Won't it also split out the DAB signal that his antenna will pick up?

Sam Russell

coylemj wrote: »

Won't it also split out the DAB signal that his antenna will pick up?

DAB is band III. FM is band II.

Band II comes out the FM connection while Band III comes out the other one marked TV.

I thought that was what he was looking for - I have no idea what the insertion loss would be.

peking97

Sam Russell wrote: »

DAB is band III. FM is band II.

Band II comes out the FM connection while Band III comes out the other one marked TV.

I thought that was what he was looking for - I have no idea what the insertion loss would be.

Yes, that is exactly what I was looking for. Thanks.

Antenna

Note that the majority of FM transmitters in the Republic of Ireland transmit VERTICAL polarisation only (unlike in the UK where most FM transmissions have mixed Vertical and Horizontal polarisation) .

So if a Halo FM aerial is what you have it will generally work better in this country installing it like this, rather than horizontal as shown in the combo aerials link from the first post (the vertical folded dipole on the linked picture is the DAB aerial, which is correct, but not so the horizontal halo aerial for FM for this country):



Installing an FM halo like this - it would also be more likely to also work for DAB (if you had no separate DAB aerial) as DAB is vertical polarization only (everywhere).

peking97

Antenna wrote: »

Note that the majority of FM transmitters in the Republic of Ireland transmit VERTICAL polarisation only (unlike in the UK where most FM transmissions have mixed Vertical and Horizontal polarisation)

You're sure about that ?

peking97

Antenna wrote: »

Note that the majority of FM transmitters in the Republic of Ireland transmit VERTICAL polarisation only (unlike in the UK where most FM transmissions have mixed Vertical and Horizontal polarisation) .

So if a Halo FM aerial is what you have it will generally work better in this country installing it like this, rather than horizontal as shown in the combo aerials link from the first post (the vertical folded dipole on the linked picture is the DAB aerial, which is correct, but not so the horizontal halo aerial for FM for this country):

That being the case would it not be best to "straighten it out" so that it looks like a normal vertical folded dipole?

Sam Russell

peking97 wrote: »

That being the case would it not be best to "straighten it out" so that it looks like a normal vertical folded dipole?

Probably. It is a folded dipole, but bent like that I'm not sure how it would be classified. A normal folded dipole is omnidirectional, but that would have a directional radiation pattern. A simple monopole might perform as well, but a dipole would be better. Folding the dipole gives easier balun design.

If the signal strength is there, then anything will probably do.

byte

http://www.aerialsandtv.com/fmanddabradio.html#FMandDABAerials That, I think, is an interesting read.

Scroll down where they do basic tests on various aerials.

peking97

Can anyone tell me what type of RF connector this is?

winston_1

It's a push on F connector.

STB.

Well done OP on spelling the word "aerial" correctly.

Winston can't but have been impressed.