Most current radar scanning antennas utilize mechanical scanning, relying on a gimbal, motor, and gear arrangements to physically rotate/elevate the antenna. This technique is slow, gravity-sensitive, and susceptible to shock and mechanical failure. High-speed multiple target tracking cannot be effectively done by this technique. Electronic scan, however, allows significantly faster scanning, requires no mechanical/physical rotation of the antenna, and lends itself to multiple-target tracking.

Ferroelectric (Paraelectric) Phase Shifters.

A great majority of current electronic scan antennas are controlled by ferrite phase shifters. These phase shifters exhibit low insertion loss and perform well, but their size and cost make them prohibitively expensive for most military and private-sector applications. The subject ferroelectric phase shifters are significantly lower in cost and smaller, and can also be electronically adjusted in real time for age and environmental stress. A large number of these ferroelectric phase shifters can be designed and placed on a single material substrate, thus further reducing the entire antenna size, weight, and cost.

E-scan Antenna utilizing phase shifters.

This antenna employs advanced ferroelectric ceramic technology and computer-aided design with planar microwave circuitry. The microwave signal is impedance-matched into the ferroelectric phase shifter, and a DC voltage is applied across the ferroelectric element, allowing change/control of the dielectric constant of the ferroelectric material, thereby varying its electrical length. These ferroelectric phase shifters are installed in the corporate feed of a microstrip antenna array. By utilization of a microcontroller and voltage amplifiers, the antenna beam can be scanned by adjusting the voltage/phase shift of the various phase filters.

Scanning antennas find use for both military and private-sector applications. Ferroelectric scanning antennas would particularly find use where low cost is a requirement, such as in scanning antennas for pleasure boats, global positioning satellite applications, single-use battlefield weapon systems, etc. Other applications include airport radar scanning systems where high-speed scan is required for multiple aircraft detection, and battlefield scenarios where multiple-target tracking is needed.

This work was performed by Richard Babbitt, Thomas Koscica, and William Drach for the Sensors and Electron Devices Directorate (SEDD) of the Army Research Laboratory. A patent has been obtained. This technology is available for licensing from the U.S. Army Research Laboratory. Inquiries with regard to this technology should be addressed to Ms. Norma Cammarata, ARL, 2800 Powder Mill Rd., AMSRL-CS-TT, Adelphi, MD 20783-1197; (301) 394-2952; fax: (301) 394-5818; E-mail: This email address is being protected from spambots. You need JavaScript enabled to view it..

Electronics Tech Briefs Magazine

This article first appeared in the November, 1998 issue of Electronics Tech Briefs Magazine.

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