What would the best way to combine 4 antennas into one distro, in order to provide coverage for an extremely wide area.
In the past i've used PW Helicals directed at almost 180∘ to each other to ensure mics are being covered by at least one antenna, however I lose any form of diversity, for mics at the far reaches.
Next time around I'd really want to add more helicals, in order to provide mics with true diversity, however the SHURE UA221 splitter/combiners seem a little "delicate" for the job.
Any recommendations would be apreciated.
When using multiple antennas to cover different zones you have to be very careful to be sure there is essentially no overlap in coverage. You have to take the antenna coverage patterns, terrain, structures, etc into consideration to eliminate covering the same area with 2 antennas on the same side of your diversity system. If you have overlapping coverage you have created an area where you are going to have multipath reception, which can cause dropouts rather than the improved coverage you are looking for.
Once you have taken those things into consideration you need a way to combine the antennas. It is possible to just use passive combiners, but you will have more control with an antenna "mixer" like the PWS DB-1C
which lets you combine up to 4 antennas with variable level of each into a mix that is then DA'd to a bunch of outputs to feed various systems. Unfortunately there is no information on their website, and I don't remember the details of how many outputs, but it is often used in large scale situations. You would need 2 of the combiners to maintain diversity, 1 for each antenna system, with each system up to 4 antennas.
If you cannot isolate the coverage of the multiple antennas you are probably better off with an omni antenna, or a very wide coverage directional antenna that can cover the entire area of interest. You can get omni antennas that have a gain higher than zero that achieve the gain by reducing the vertical coverage while maintaining an omni horizontal pattern.