Antenna configurations
The positioning of the antenna is of the up most importance and is one of the main factors in
determining system range.
The following notes should assist in obtaining optimum performance:-
1. Keep it clear of other metal in the system, particularly the ‘hot’ (top) end.
2. The best position by far, is sticking out the top of the product. This is often not desirable for
practical/ergonomic reasons thus a compromise my need to be reached.
3. If an internal antenna must be used try to keep it away from other metal components, particularly
large ones like transformers, batteries and PCB tracks/earth plane. The space around the antenna is
as important as the antenna itself.
4. Keep it away from interference sources, bad interference can easily reduce system range by a factor
of 5. High speed logic is one of the worst in this respect fast logic edges have harmonics which extend
into the UHF band and the PCB tracks radiate these harmonics most efficiently. Single chip
microprocessors and ground planed logic boards reduce this problem significantly.
The next diagrams (fig 6) show three different antenna configurations which can be used on both the
transmitter and the receiver. Additionally a coax fed external dipole or 1/4 wave ground plane antenna
may be considered if system range is paramount.
figure 6: Antenna configurations
Radiometrix Ltd, SILRX-UHF Data Sheet
page 7
RADIOMETRIX [ RADIOMETRIX LTD ]
