The availability of the wireless microphone (service area) is determined by how the antenna is installed. This page explains the knowledge about antennas and how they should be positioned.

Type of Antenna

If a receiver (tuner) has an antenna attached, you can use a wireless microphone in its vicinity.
However, it is not guaranteed that the microphone will always be used in the vicinity of the receiver.
​If the microphone's usage location and the placement of the receiver are different, you will need an extended antenna.

Service Area

he area covered by the radio waves transmitted by the transmitter is referred to as the service area. The extent of the service area depends on factors such as the model specifications, transmission method, or sensitivity of the receiving side.
A tuner or antenna should be positioned within the service area. If the transmitter is in motion and the antenna or tuner goes beyond the service area, it may result in sound interruptions.

The service area may be blocked by a shield (ex. wall). Or may also be transparent, but it will be narrower. The degree of transmission depends on the transmission method and the material of the shield.

​Multiple Radio Channels and the Number of Antennas

The confusion between multiple radio channels and the number of antennas often arises. This section aims to clarify these two aspects.

It should be reiterated that the number of radio signals (which can be considered as the number of microphones) and the decision on how many antennas to install or whether to use diversity have absolutely no correlation.

How many antennas should be installed and where?

Designers should design to cover the entire space where the service area around the antenna is used. 

Actually, that's all there is to it.
​Please be mindful that the size, shape, and orientation of the service area can vary depending on the antenna. The service area around the antenna is likely documented in the user manual or similar documentation.

The content of this page concludes here, but a brief detailed explanation will be provided at the end.
You might be wondering whether the service area is around the transmitter or around the antenna and receiver.​

The decision on antenna placement equates to designing the serviceable area. To verify the service area, there are two approaches. One is the idea that the service area is around the antenna (or receiver). The other is the concept that the service area is around the transmitter. Physically, the latter is correct; however, in practice, the former is a more convenient perspective for design.