Q: “Why do some wireless receivers have one antenna and others have two?”
A: Generally speaking, wireless receivers are available in two different configurations. The first is a single antenna receiver, which utilizes one receiving antenna and one tuner, similar to an FM radio. Single antenna receivers work well in many applications, but are sometimes subject to momentary interruptions or “dropouts” in the signal as the person holding or wearing the transmitter moves around the room.
Diversity receivers often provide better performance. They utilize two separate antennas spaced a short distance apart and (usually) two separate tuners. An “intelligent” circuit in the receiver automatically selects the better of the two signals, or in some cases a blend of both. Since one of the antennas will usually be receiving a clean signal at any given moment, the chances of a dropout occurring are reduced.
So, are diversity receivers (or two antenna systems) better? They usually have fewer dropouts when used in tough environments. Single antenna systems are generally cheaper than diversity systems, but if reception without dropout is your prime goal, a diversity system is the way to go!