Ten switched-beams with 2 x 2 series-fed 2.4 GHz array antenna and a simple beam-switching network

Official URL: http://dx.doi.org/10.1002/mmce.22184

This article presents a 2 x 2 series fed 2.4 GHz patch antenna array having multiple beam switching capabilities by using two simple 3 dB/90 degrees couplers to achieve required amplitude and phase excitations for array elements with reduced complexity, cost and size. The beam switching performance with consistent gain and low side lobe levels (SLL) is achieved by exciting the array elements from orthogonally placed thin quarter-wave (lambda(g)/4) feeds. The implemented array is capable to generate ten (10) switched-beams in 2-D space when series fed elements are excited from respective ports through 3 dB quadrature couplers. The dual polarized characteristics of presented array provide intrinsic interport isolation between perpendicularly placed ports through polarization diversity to achieve independent beam switching capabilities for intended directions. The implemented antenna array on 1.575 mm thick low loss (tan delta = 0.003) NH9450 substrate with epsilon(r) = 4.5 +/- 0.10 provides 10 dB return loss impedance bandwidth of more than 50 MHz. The measured beam switching loss is around 0.8 dB for beams switched at theta = +/- 20 degrees, CYRILLIC CAPITAL LETTER EF = 0 degrees, 90 degrees, and 45 degrees with average peak gain of 9.5 dBi and SLL <= -10 dB in all cases. The novelty of this work is the capability of generating ten dual polarized switched-beams by using only two 3 dB/90 degrees couplers as beam controllers.