When you are installing wireless microphone systems you should consider the following :

• Maintain a direct line of sight between the transmitters [Handheld or Bodypack] and receiver antennas
• Place the receiver/antennas at least 1.5m away from all transmitters
• Place the receiver antennas at least 1.5m away from any large metal objects, wire (particularly wire mesh) or sheet metal structures, walls, ceilings, etc.
• Do not place the antennas in hidden places (behind walls)
• Place the receiver/antennas at least 1.5m away from any equipment that may emit RF radiation, such as lighting racks, fluorescent lamps, LED screens, digital effect units, PCs, digital video equipment, etc.