Compact Quasi-Planar Four-Way Power Divider With Wide Isolation Bandwidth

A novel compact quasi-planar four-way power divider with a wide isolation bandwidth is proposed in this paper. The signal is fed through the coplanar waveguide and then divided to the four microstrip-line output ports through a metal via. To realize the high output isolation, the multi-layer circuit structure is used. The isolation network is composed of four isolation resistors and a metal via (common node). Equivalent circuits are given to analyze and design the novel power divider. The detailed analyses are given according to the equivalent circuits. A four-way high-isolation power divider with the center frequency of 2.1 GHz is designed and fabricated. The measured 20-dB relative isolation bandwidth between the output ports is about 58%, while 30-dB relative isolation bandwidth between the output ports is about 10%. The measured results agree well with the simulated ones. The total size of the fabricated four-way power divider is
$0.17\lambda _{g} \times 0.22\lambda _{g}\,\,(\lambda _{g}$
is the wavelength of the center frequency). It shows that the proposed power divider has not only the advantages of high output isolation and compact size but also the advantages of excellent output and input impedance matching and very low insertion loss. The presented power divider can be used in antenna feed, power-combining amplifier, and so on.