In-phase power divider with three octaves band using microstrip to slotline transitions and loosely coupled microstrip lines

The design of an in-phase planar power divider operating over a wide frequency band is presented. The proposed device uses a modified single section Wilkinson structure. The main feature of the proposed device is a broadside coupled microstrip/slotline configuration instead of using T-junction at the input port of the traditional design. Moreover, a pair of loosely coupled microstrip lines with two isolation resistors is used to enhance the matching of the output ports. The proposed structure provides 140% fractional bandwidth based on 15 dB isolation reference. The equivalent overall size of the structure is 0.25 λ_g × 0.25 λ_g, where λ_g is the guided wavelength at the lowest operating frequency. The simulated results of the proposed divider show equal power division with less than 0.5 dB additional insertion loss, more than 15 dB isolation and more than 10 dB return loss over the band 1.4 GHz-8 GHz. The device has equal power division between the two output ports with less than 0.5 dB amplitude imbalances and less than 2° phase imbalance across the band 1-8 GHz.