Microstrip Quad Mode Reconfigurable Power Divider

Abstract

The evolution in communication systems demands low cost, compact size, reconfigurable or multi-functional microwave circuits that are easy to integrate. In this project a quad mode reconfigurable power divider, based on the design presented by Yahya Antar et. al [1], was designed, fabricated, and tested. Reconfigurability was obtained by converting two ports of a quadrature coupler ports into a single input port with the help of a feeding structure made of parallel coupled microstrip transmission lines. The four modes of operation discussed in this work includes (0:1), (1:0), (1: j) & (j:1), i.e. directing total power into one out of two ports and two-way equal power split with +90 or – 90 degrees phase shifts. All the four modes were designed and simulated using Keysight ADS. Reconfigurability was achieved by employing 4-switches. Out of four switches 2 switches were placed at the end of coupled lines and the remaining two at the center of quadrature coupler. In this project instead of switches through hole via to ground were used to control the mode of operation of the power divider. Out of these four modes, fabrication was done for only two modes of operation (0:1) & (1: j). A very close agreement between the simulated and measured results was achieved. Simulated results of reconfigurable quadrature coupler operating in mode (0,1) were 𝑆11 = −22.988 dB, 𝑆21 = −27.263 dB and 𝑆31= − 0.114 dB and the measured results for this mode were 𝑆11= − 25.75 dB, 𝑆21 = −23.39 dB and 𝑆31 = −0.948 dB representing that almost all the power is delivered to port 3. Moreover, the simulated results of circuit operating in mode (1,j) were 𝑆11 = −24.522 dB, 𝑆21 = −3.2 dB and 𝑆31 = −2.9 dB and the phase difference was of -90 degrees while measured results for this mode of operation were 𝑆11 = −24.22 dB, 𝑆21 = −3.463 dB and 𝑆31 = −3.903 dB and the phase difference obtained was -93.7 degrees, showing quadrature mode of operation and almost equal split of power between the port 2 & port 3.