Implementation of a Microstrip Square Planar N-Way Metamaterial Power Divider

Abstract

This paper describes a compact square-shaped 20-way metamaterial power divider implemented in microstrip technology and lumped capacitors and inductors. The divider comprises 12 square tiles exhibiting left-handed behavior and 13 square tiles exhibiting right-handed behavior arranged in a checkerboard tessellation (or mosaic). The divider relies upon the infinite wavelength phenomena in two dimensions and this requires the left-handed tiles have an insertion phase between any two of its sides equal to, but with opposite sign, of that of the right-handed tiles. To achieve tessellation, both tile types must be the same size. The design method is based upon an analytic formulation, and was applied to the realization of a 20-way power divider operating at 1 GHz that uses surface-mount lumped components. The resulting divider was 50 mm by 50 mm. Over a 10% bandwidth, the measured insertion loss was less than 1.3 dB, the measured couplings track within plusmn1 dB and plusmn6deg , and the measured input port return loss and isolation was greater than 20 dB. This level of isolation was achieved without isolation resistors. Equal in-phase power division to output ports on the square-shaped periphery allows compact integration with other planar circuit modules in a combined amplifier. The design method can be extended to N-way power division where N is an odd integer multiple of 4.