Depending on the type of sport, you may need to adjust the value for Loop Power. For example for cycling, where a high precision is needed and the transponder is fixed on the fork of the bike close to the loop, you need to choose a low value like 30%. In case participants wear the transponder on their wrist and can finish with their arms raised, choose a high loop power like 80% or 100%.
The environment near the finish line can have an influence on the read height. Always check with a transponder that you get the expected read height from your loop. Read more on this in Checking Read Height