A mutual coupling study of linear polarized microstrip antennas for use in BLAST wireless communications architecture

The analysis of aperture coupled linear polarized microstrip antennas for use in multielement antenna arrays is presented. The goal is to place independent antenna elements as close as physically possible with minimum mutual coupling. For antennas on a rigid foam plastic substrate, /spl epsiv//sub ra/=1.07, the mutual coupling between two antennas is symmetric in both the E-plane and H-plane. For antennas on PTFE and ceramic polymer composite substrates, /spl epsiv//sub ra/=2.2 and 4.5, respectively, the mutual coupling is nonsymmetric with mutual coupling greater in the E-plane for large interelement spacings. The mutual coupling can be significantly reduced (20-35 dB) at the same interelement spacing when adjacent elements transmit (recieve) orthogonal senses of polarization. The magnitude of the mutual coupling can be reduced by decreasing the antenna substrate thickness. The mutual coupling is independent of the feed substrate dielectric constant value. The center frequency, f/sub 0/=5.22 GHz, is chosen to lie within the Personal Communications Service (PCS) band 5.1-5.3 GHz. The substrate thicknesses chosen are thin (d/sub a///spl lambda//sub 0/<0.1) so as to be compatible with low profile thickness requirements of portable communications systems.