Design of Novel Compact Coupled Microstrip Power Divider With Harmonic Suppression

A new microstrip power divider (PD) is proposed which consists of a pair of parallel coupled-lines (PCLs) on a defected ground, and its two outputs are connected by a resistor and a capacitor. The even/odd-mode analysis shows that the defected ground structure (DGS) etched on the ground plane of PCL is equivalent to a strong parallel resonance circuit in the case of even-mode, and a weak inductance in the case of odd-mode. So, this kind of additional reactance effect is used intentionally to design compact coupled microstrip PD with harmonic suppression. Also, the phase-delay through the PD is discussed, which is different from conventional one. A 0.9 GHz PD is developed and experimental results verify it has low insertion loss, good impedance matching and isolation. Furthermore, the third harmonic suppression of this PD is better than ${-}35$ dB and the overall area of divider is only 34% of the conventional case.