Adaptive arrays using a complex learning algorithm

Abstract

The demand for the mobile communications is increasing every year, and TV and automobile telephone by satellite communication are expected to find wider applications. If individuals are to carry communication equipment, then the equipment must be small size, lightweight and highly efficient. To realize antennas which must also be of small size, lightweight and highly efficient. For such equipment it is desirable to employ the adaptive array with phase control. Conventionally, the LMS algorithm has been applied frequently in the design of the adaptive array. However, the authors believe that the learning algorithm is better suited to the adaptive array because of its higher convergence speed and the clear specification of the convergence condition. This paper extends the real-type learning algorithm to the complex-type learning algorithm. The convergence condition for the algorithm is derived, and the result of the application of the method to the adaptive array is shown. A method of deriving the reference wave also is presented which is less affected by the input signal variation and is suited to the adaptive array with only the phase control. Using the proposed complex learning algorithm and the new reference wave, the phase-controlled adaptive array is designed. A satisfactory result is obtained by simulation.