Part of our Getting On The Air guide.
Diversity receive is a technique borrowed from serious contest and DX stations, using a second antenna and receiver simultaneously to fight noise and interference in a way a single antenna simply cannot.
The Core Idea
Local noise and interference often affect two physically separated antennas differently, since the noise source has a specific location and propagation path to each antenna. A weak signal you are trying to copy, especially DX arriving via distant ionospheric propagation, often shows up similarly on both antennas since it is coming from far away. By listening to both antennas simultaneously and comparing or blending the two received signals, a diversity setup can suppress locally-sourced noise that only shows up strongly on one antenna while preserving the distant signal present on both.
What It Actually Takes
A genuine diversity receive setup needs two separate antennas, ideally with some real physical or polarization separation between them, feeding two independent receivers or a radio with true dual-receive capability, plus a way to combine or compare the two received audio streams. This is meaningfully more setup than most casual stations run, which is why diversity receive remains mostly a serious DXer and contester technique rather than something typical home stations bother with.
Simpler Approximations
You do not need a full dual-receiver diversity rig to get some benefit from this concept. Simply having a second, differently oriented or positioned receive antenna that you can quickly switch to when a signal is buried in noise gives you a manual, lower-tech version of the same benefit: comparing what two different antennas hear and picking whichever copy is cleaner.
Is It Worth Building
If you are chasing weak DX regularly and your noise floor is a limiting factor, even a simple secondary receive antenna, like a low-noise loop or a Beverage-style wire, that you can switch to for comparison purposes, delivers real practical benefit without the complexity of a full simultaneous diversity setup. It is a technique worth knowing about even if you never build the full version.