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Multiway Radio Mics - 6 - Setting up the system 2

4. Place your aerials.
This is probably the most crucial part of the whole set up procedure. We supply one of two types of aerial - the dipole or the yagi (pictured below). Multi-way systems are usually supplied with an Antenna Distribution Amplifier (sometimes called an ADA or DA), which takes the signal from a pair of aerials and distributes their output to a number of receivers. This means you don't have to rely on the short aerials on the back of the receivers (see the picture on P2) which have limited range and positioning possibilities.


UHF Dipole antena	UHF Yagi antennae

The dipole antenna with the reflector is slightly directional, and should be positioned so that it 'points' in the direction of the arrow. The Yagi antenna (which will look familiar as it is the design used for TV aerials) is very directional and again should be pointed in the direction of the arrow. It can give up to 8dB extra gain but should be used with caution if the stage is wide.
In general, aerials should be positioned as close as possible to the transmitters and as far away as possible from any potential sources of interference. Another pointer is to try and keep them away from walls, and particularly away from corners. It is possible that a reflected signal from a wall arrives at the antenna with enough level and exactly 180 degrees 'out of phase' for the two signals (the direct and the reflected) to perfectly cancel each other out. This will vary with the travel time to the antennae, so you may get 'bursts' of interference or loss of signal as the performer moves around. Metal structures (lighting trusses) may also act as reflectors.
You may also experiment with the height of the antenna. In some places, higher may be better, but in others it may increase the liklyhood of interference, particularly from high-power TV transmitters.
If you are planning to have your antennae more than 10m from your receivers, then you should use the thicker URM cable as it exhibits less signal loss - it is pointless moving your antennae closer to the transmitters and then sending it down 20m of cable that then looses more signal than you have gained. See the catalogue page for our URM cable for a comparison table.

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