Wireless Microphones: Application and Positioning

Signal path from transmitter to receiver

Transmitter signals radiate in all directions, not just in a direct path. This causes reflections on walls, floors and ceilings which overlap with the directly sent signal.

With single antenna receivers, so called non-diversity systems, direct and reflected signal can often cancel each other out, causing a sound drop out. Diversity receivers with two antennas are better able to handle longer distances and more cluttered signal paths. They are also more reliable in settings where there is no line of sight between the receiver and the transmitter.




Receiver and antenna placement

  • Place the receiver properly: Receivers are not only subject to interference from external sources that use radio frequencies. Where possible, keep receivers also a few feet (or rack spaces) away from CD/ DAT/ MD players, PCs/ notebooks and special-effect units.
  • Position antennas properly: Ideally, antennas should be positioned above an audience or other obstructions so that the transmitter and receiver can “see“ one another. When receivers are mounted in a rack, antennas must be located on the front panel or allowed to project through the top of the rack. With diversity receivers the antennas should be oriented at a 45-degree angle to maximize the distance between the tips. To receive the optimal diversity effect the antennas should have a distance of 40 cm (one wave length). Less distance deteriorates this effect.

The usage of an antenna splitter

If you operate more than one wireless system and move from venue to venue, it is usually more convenient to mount receivers in a rack case. This degrades the performance of the wireless systems as the antennas are too close to one another.

With more advanced wireless systems the antennas are detachable which allows the usage of an antenna splitter. The splitter feeds one “master” pair of antennas to serve all receivers for an increased RF-reliability. With four or more receivers in one rack we recommend to use an antenna splitter as this leads to a significant improvement in performance.

Power supply

Unlike most wired microphones, all wireless transmitters require batteries. As a result, batteries are an important and constant replacement part that should also be checked regularly.

The usage of rechargeable batteries is possible. Rechargeable mignon (AA) batteries are recommendable as they are available with a capacity of 2500 mAh or even more – the more capacity, the longer the battery life. Unfortunately, there are no rechargeable 9 V batteries available that offer an appropriate capacity.

Alkali 9 V batteries offer twice the battery life. But if the usage is less than three hours, rechargeable 9 V batteries can be used as well.


 

Setup Snapshots for wireless microphone systems

Wireless singer setup





 

Wireless presentation setup





 

Wireless guitarist setup





 

Wireless saxophone player setup




 


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