Design of Wideband Filtering Power Divider with Compact Size and High Isolation

A compact wideband filtering power divider (FPD) with high isolation is designed based on a microstrip line (MSL) and coplanar waveguide (CPW) hybrid structure. By virtue of the broadside coupling, a three-port filtering network is wisely constructed with three parallel microstrip feeding lines and one CPW quarter-wavelength resonator. Then, to achieve the port-to-port isolation, a lumped resistor is loaded between the two ends of the output feeding lines. To explain the working principles of filtering and isolation, the even-/odd-mode analysis method is adopted. For demonstration, a prototype of wideband FPD operating at 2 GHz with a 3-dB fractional bandwidth of 100
^%
is designed, fabricated and tested. Final circuit dimension is only 0.2 9λ
_g
XO.07λ
_g
, where λ
_g
is the guided wavelength at the center frequency. Measured results indicate that the proposed wideband FPD has achieved 18-dB return loss and 21-dB in-band isolation.