Adjustable millimeter wave in-phase power divider for 5G using a three-line coupler structure

An adjustable power divider that operates at millimeter wave band (28 GHz) for 5G mobile systems is proposed. The divider is designed using three parallel-coupled microstrip lines with a slotted ground plan. The output power is adjusted by using two varactors. A chip resistor is connected between the two output ports to enhance the isolation, whereas two open-ended stubs at the output ports are used to enhance the matching of those ports. The simulated results show that this device can vary the ratio of the two output powers from 1:1 to 1:2.3 across the band 27 to 29 GHz. The simulation also shows that more than 10 dB of return loss and isolation are achieved across the whole tuning range.