Meet the Challenge of Designing Electrically Small Antennas (.PDF Download)

Antennas are vital for communications devices, although the continuing miniaturization of communications products has forced antenna designers to follow suit. However, due to the fundamental limitations in size and performance (Chu’s limit), achieving miniaturization with good antenna performance is challenging. Electrically small antennas (ESAs) are limited in bandwidth and radiating efficiency.

By understanding the effects of antenna size reduction on quality factor (Q), bandwidth, efficiency, and gain, it is possible to design a miniature antenna without drastically compromising performance. To demonstrate the effectiveness of this approach, an ESA was designed and developed for GPS (1.575 GHz) at one-tenth the operating wavelength. As will be shown, the Q of this proposed antenna design is closer to Chu’s limit that an equivalent-sized dipole or loop antenna.