Multilayer unequal microstrip power divider

Design of power dividers are critical for large array antennas, where radiation patterns are controlled by adjusting the magnitudes and phases of the patch excitation signals [1]. In a non-uniform array, side-lobe levels are often reduced by tapering the excitation magnitudes of individual patch to strength the radiation from the central patches. This requires the design of efficient and easy to integrate unequal power dividers with typical power split ratios in excess of -3 dB and as high as -10 dB [2]. Wilkinson power dividers are widely used for equal power division due to their simplicity and high isolation between output ports [3]. But Wilkinson type unequal power splitters require microstrip lines with very high impedance, i.e. very low aspect ratio (W/h), which are often impractical to realize using conventional microstrip technology. Introducing defected ground structure in the design improves the aspect ratio but incorporates a new challenge in the fabrication process [4]. In this article, the design of a C-band multilayer aperture coupled microstrip power divider with unequal power split is presented. Multilayer structure is selected to reduce the size of the power divider use recent multilayer integration technology, such as low-temperature co-fired ceramics (LTCC) and multi-chip modules [5]. Professional EM-simulator is used to optimize the S-parameter response of the designed two way 2:1 power divider. A prototype is fabricated using in-house printed circuit facility and experimental results are presented and compared with the simulated response.