High-gain side-firing helical antennas for ultrahigh-frequency television broadcasting

IN designing any high-frequency device which is to have relatively uniform characteristics over a band of frequencies, one of the prime considerations for easing the severity of design compromises is to choose a basic configuration inherently suited to maintaining the reactive energies of the system low compared with the energy flow per cycle through the device. Such a smooth flow through the system can be approached by maintaining the impedances throughout the system resistive over the desired performance frequency band. This in turn dictates the avoidance of resonant components since such resonant elements tend to introduce high reactance slopes into the system impedances requiring careful compensation in the design. The case of the uniform transmission line with distributed constants properly arranged so as to minimize reflections is perhaps the ideal example of such a system.