High-frequency antennas transmit radio waves across vast distances and even over mountain ranges using very little energy, making them ideal for military communications. These devices, however, have one big problem: They need to be huge to operate efficiently. Engineers at the University of Wisconsin–Madison are working to increase the effective size of antennas by turning military vehicles that carry them into transmitters - using the structures that support the antennas themselves to help broadcast signals.
Troops in remote locations need to communicate by radio and move quickly, unencumbered by heavy and unwieldy equipment. However, antennas need to be at least one-quarter the length of the radio wavelength that they transmit in order to operate efficiently. High-frequency military signals use radio waves with wavelengths ranging from roughly a football field in length to the distance of a successful first down - 10 yards. Even at the small end, the ideal size for an antenna is taller than an average adult. And Putting a big, long antenna on top of an amphibious assault vehicle would be too high-profile.
Short antennas on the other hand lighten loads at steep costs to performance. These devices are inefficient, dissipating as much as 90 percent of input power as useless heat instead of useful broadcast radio signals.
So increasing the size of an antenna without adding to its physical dimensions was impossible. However, real-world military antennas are almost always attached to other things - for example, large, metallic objects like trucks and armored transport or amphibious assault vehicles - and engineers proposed that these structures themselves could broadcast radio signals. They are proposing to use the platform itself as the antenna. It’s a clever way to go around the limitations set by the laws of physics. From a practical point of view, the volume of the object on the military platform is the same, but they effectively achieve a larger antenna.
Turning trucks into transmitters not only makes antennas more efficient, but also enhances communication in the field by enabling one device to send and receive multiple types of information.
Separate transmitters handle internet data, Bluetooth connections, and cellphone calls, because each signal uses a particular bandwidth. As a result, military vehicles sprout metal forests of ungainly antennas high overhead. Some scientists have speculated that a yet-undiscovered material with unusual properties could pave the way to ultra-wideband antennas that could handle several broadcast types simultaneously, but those predictions remain unsubstantiated.
