Sabine Wireless: Application and Troubleshooting Guide 4 of 12
extension antennas should be in a good pickup position at all times
but
separated by about ten or fifteen feet if the antennas are within 100 or so feet.
If you put the antennas too far apart, i.e., at opposite ends of the room, or in
separate rooms, to improve coverage, diversity is defeated and you will get
dropouts. In other words, diversity is more important than coverage.
1.4.10.
If you mount the
extension antennas in the ceiling
, the antennas metallic
backplane must be orientated parallel to the floor and the antennas must not be
blocked by pillars, lights or similar obstructions. Aim the hole in the plastic cover
toward the performance area.
1.4.11.
Extension Antenna Cables
Use 50 Ohm coax cable to connect the
extension antennas to the receiver or to the distribution amp. If the cable is about
50 feet or less, use Belden RG58 or equivalent cable. These cables use a TNC
connector, and are compatible with Sabine’s receivers and antennas. Sabine
offers this cable in 15 or 30 foot lengths (SWACA15-TNC or SWACA30-TNC). Use
Belden RG8, or equivalent, for longer cable runs to reduce signal loss. These
cables require an N- connector. Use the Sabine SWATNC-N adaptor cable to
connect the RG8 cables to the extension antenna. Check your connections
carefully – poorly installed connectors are a major cause of dropouts!
1.4.12. The
left and right antenna cables should be the same length
. Different
lengths could defeat diversity and cause dropouts.
1.4.13.
The extension antennas pick up pattern is limited to the front side with the
plastic cover. There is very little sensitivity on the metallic backside.
1.4.14.
Antenna Splitter
A number of articles have been published warning against
stringing antennas in series in an attempt to extend the operating range of a
wireless microphone system. They warn about dropouts resulting from comb-filter
interference. What these articles forget is that microphone systems have diversity.
The chance of both sets of antennas will experience a filter at the same location
and time is extremely low, especially if the antennas are offset as per the following
diagram: