One of the guys that just joined our MARS unit sells radio equipment and systems to military customers. They have unique requirements and applications that are different than most hams' use cases. One such use case is the ability to put up an NVIS HF antenna that operates from 1.8-30 Mhz, be stealthy, and have reliable comms out to 200-500 miles. Here is an example of just such an antenna that he's working on and testing on our MARS net. It lays on the ground in an H configuration, about 300 feet long and uses some specialty baluns (I haven't seen them myself). Remember, the guys that would use this in the field aren't antenna experts and just need it to work. Yesterday he was able to successfully communicate with other stations about 200 miles out and he was running less than 20 watts on 7 Mhz. Neat stuff!