MEMS Electronically Steerable Antennas for Fire Control Radars

Large apertures are of great benefit to applications that are prime powered limited as is found on aerostat and other airborne platforms. Electronically scanned array antennas are often proposed for these applications. However, increasing the aperture area with conventional array technology is met with prohibitive cost, weight, and prime power increases because of the dense spacing of phase shifters and/or active T/R modules. This discusses the recent development of RF MEMS (Microelectromechanical System) switch technology and the use of these switches in a Radanttrade lens configuration for arrays of approximately 10 m² at X-band. A proof-of-concept 0.4 m² MEMS Electronically Steerable Antenna (ESA) containing 25,000 MEMS switches has been successfully designed, fabricated, and tested. The 0.4 m² MEMS ESA was then integrated with an AN/APG-67 radar system to form the MEMS Demonstration Radar System. The MEMS Demonstration Radar System successfully detected both airborne and ground moving targets during a series of extensive radar demonstrations. This is believed to be the first large scale employment of MEMS switches in a scanning antenna and radar system. The low-cost, lightweight, and low power technology demonstrated can enable weight and power constrained platforms with electronic steering.     

Analog clutter cancellation algorithms for dynamic range reduction

A technique that effectively reduces the dynamic range of the input signal in a radar receiver prior to digitization is presented. The dynamic range reduction is accomplished through a process that predicts the next radar return signal from the previous return signals, generates a replica waveform, and subtracts this replica waveform from the radar return signal prior to digitization. This process allows the radar return signal to be digitized without distortion by an analog-to-digital converter (ADC) having a limited dynamic range. The full dynamic range of the radar return signal is then restored by adding the replica waveform to the ADC output. Test and evaluation results using both synthetic and recorded radar data demonstrate in excess of a 30-dB reduction in the dynamic range of the signal at the ADC input when strong clutter is present