1. INTRODUCTION
Synthesizing the array pattern of antenna arrays has been a subject
to several studies and investigations to improve the performance of
mobile and wireless communication systems through e±cient spectrum
utilization, increasing channel capacity, extending coverage area,
tailoring beam shape etc. [1]. Among the di®erent types of antenna
array, Concentric circular antenna array (CCAA) has become most
popular in mobile and wireless communications. CCAA that contains
many concentric circular rings of di®erent radii and number of elements
has several advantages including the °exibility in array pattern
synthesis and design both in narrowband and broadband beamforming
applications [2, 3]. CCAA is also favored in direction of arrival (DOA)
applications since it provides almost invariant azimuth angle coverage.
In addition, the frequency invariant characteristics of CCAA [4, 5] have
been proved for wideband applications.