Active integrated antennas (AIAs) with one or more active devices and circuits within the radiating element have been garnering quite a bit of attention. They promise to deliver advantages like compact size, low cost, and adaptability to phased-array-antenna systems. Recently, an AIA element was successfully fabricated on a high-dielectric-constant ({? r} = 10.2) microwave laminate that is 0.635 mm thick. The development hails from Carl H. Mueller, Carol L. Kory, and Kevin M. Lambert from QinetQ's Mission Solutions Group ( together with Richard Q. Lee, Robert R. Romanofsky, and Fe'lix A. Miranda from the NASA-Glenn Research Center's Antenna, Microwave, and Optical System Branch. They were joined in this effort by Frederick W. Van Keuls from the Ohio Aerospace Institute.

That antenna consists of a transmissionfeedback oscillator loaded with a microstrip antenna. The oscillator antenna comprises a very-low-noise, high-frequency field-effect transistor (HF FET) from NEC ( The FET is integrated into the center of a segmented patch antenna that was designed for X-band at 8.5 GHz. At 5 x 6 mm2, the antenna is smaller than most X-band AIAseven though it also was fabricated using microwave laminate and surface-mount active and passive devices.

The researchers set out to improve the phase noise of AIAs fabricated on high ? r substrates while achieving high radiated power levels and good radiation efficiency. See "Small-Size X-Band Active Integrated Antenna with Feedback Loop," IEEE Transactions on Antennas and Propagation, May 2008, p. 1236.