Antenna choice… it’s like choosing the type of hose to use because you need the right water pressure coming out or choosing the right size spoon to eat with.
There are RX (Receiving) and TX (Transmitting) antennas, there are antennas that do both, these talk to the wireless gear in use…. choose the wrong antenna for your application, and you may not be happy.
After a site visit, where I perform a scan of the event area over a certain amount of time, I have a picture in my head of the type of antenna I want to use, depending on the scan results. If the white space in the area is not minimal or your show has more wireless gear besides yours, you want to focus a lot more on your performance area…. well you always need to focus on the performance area… but in this instance, you need a directional antenna (helical for narrower and longer throw, paddle antenna covers a wider area but still has good coverage due to coverage pattern).
Real estate…. for the antennas to have good reception, they need to have good line of sight. If signal is blocked or interrupted by objects like metal, human bodies(signal being blocked by audience) and thick concrete, you are likely to have issues.
Try as much as you can to stay away from the antenna gain switch…this is to compensate for signal loss caused by cable length. If used unnecessarily, this may cause issues for you.