Andrew Steele

Television & Radio Hardware - Radio

Installation of external or loft aerials for use with radio receivers are much more rare than their television counterparts, however they can provide an excellent signal instead of device integrated or loop aerials.

It is still good practice to consider the aerial, cable, connectors, and surface plates carefully and to purchase those of good quality as with television installs, however radio reception is much more tolerant of a lower quality install.

Before planning the installation, it is key to check that the device has the facility to connect to an external aerial as many do not.

FM/AM vs DAB

The choice between wanting an FM/AM or DAB signal will mostly depend on the receiving device. Both can be received perfectly well with some aerials, however it will be necessary to choice which will be the priority.

Aerial

There are a variety of aerial types, some more suited to FM/AM reception and others more suited to DAB. A few are also suited to both.

FM Omnidirectional
– Will only work well in a strong signal area.
FM Half Wave Dipole
– Mounted vertically, this aerial can be omni-directional. Also relatively good for picking up DAB signals.
FM Folded Dipole
– Better for locations exposed to the weather due to the design making it stronger.
FM 3 Element
– Best suited to areas with poor signals. Flimsy design means it will probably not last in exposed places. Very directional so more readily rejects unwanted signals.
FM 6 Element
– Best choice for very poor signal areas. Not suitable for windy locations due to size and construction design.

For people more interested in FM reception, a Half Wave Dipole is the best choice. A 3 Element could be purchased if unsure of whether signal area is strong enough, and even cut down to make a Half Wave Dipole if it is.

DAB Dipole
– Very good for DAB signals and of strong construction, so suitable for windy locations.
DAB 3 Element
– Best suited in locations with poorer signals.
DAB 5 Element
– Ideal for very poor signal areas. Design makes it quite flimsy so not good for breezy places.

A DAB dipole is ideal for most people just concerned about DAB reception. As with FM, a 3 Element could be purchased for those unsure of the signal, and cut down to create a Dipole if necessary.

For the best signal in both cases for the average person, separate aerials are recommended. However, in some cases the device may only have a single input for both FM/AM and DAB. There are a couple of ways around this, however if a single aerial is wanted the FM Half Wave Dipole or DAB Dipole could be purchased and should work well – however it is important to make sure they have no Balun as this will kill the signal for the reception type the aerial is not intended to receive.

Cable

The recommendation,as with television, is still to use WF100 cable on radio installations. Although alternatives such as WF65 or even RG-6 will usually work perfectly well, it is best practice to future proof.

It is important to ensure that the cable is impedance matched. This is usually rated at 75 Ohm, however some receivers require a 50 Ohm signal.

Multiplexing

If the radio cable is to run to a point near a television aerial or satellite receiver, the radio signal can be multiplexed onto the downlead, and split again using an appropriate surface plate.

Many mains distribution amps accept inputs for VHF/FM/DAB alongside UHF/TV. However, older amplifiers may not accept DAB signals on the VHF/FM input, so care should be taken to check whether multiplexing on an particular amplifier will work.

Polarisation

The polarisation of the aerial applies to radio broadcasting as with television. Most aerials used for FM reception should be vertically polarised, and all DAB transmissions require a vertical polarisation.