This chapter presents several innovations that have taken place since the first edition of this book. Wireless communication applications often resort to very simple beam switching, in which multiple beams simultaneously exist and the one with the best signal reception is selected. Moving radars or sonars must deal with clutter as well as interfering signals. Space-time adaptive processing (STAP) combines a spatial adaptive array with a temporal adaptive array to improve clutter cancellation and null placement. Another relatively recent development is multiple input, multiple output (MIMO) antenna array systems where an adaptive array is used for both transmit and receive to increase channel capacity. Reconfigurable antennas change their physical layout using switches to adapt for example the pattern, frequency response, and polarization response to match the desired signal. Partial adaptivity is of interest when only a portion of the total number of elements is controlled, thereby reducing the number of processors required to achieve an acceptable level of adaptive array performance.

Chapter Contents:

• 12.1 Beam Switching
• 12.2 Space-Time Adaptive Processing
• 12.3 MIMO
• 12.4 Reconfigurable Antennas and Arrays
• 12.5 Performance Characteristics of Large Sonar Arrays
• 12.6 Adaptive Processing for Monopulse Tracking Antennas
• 12.7 Partially Adaptive Arrays
• 12.8 Summary and Conclusions
• 12.9 Problems
• 12.10 References

Inspec keywords: interference suppression; adaptive antenna arrays; space-time adaptive processing; MIMO communication

Other keywords: beam switching; multiple input multiple output antenna array systems MIMO antenna array; clutter signal; clutter cancellation; wireless communication application; interfering signal; null placement; space time adaptive processing; spatial adaptive array; partial adaptivity; temporal adaptive array; adaptive arrays

Subjects: Electromagnetic compatibility and interference; Signal processing and detection; Antenna arrays