A Dual-Band Coupled Line Power Divider Using SISL Technology

A coupled-line based dual-band power divider using substrate integrated suspended line (SISL) for WLAN application is proposed in this brief. Two-section cascaded coupled line in each output path is used for dual-band response. One coupled line loaded at the input port is to improve the frequency selectivity. Two lumped resistors placed between two pairs of the two-section coupled line are used for isolation enhancement. Multi-layer SISL structure is introduced to realize tight broadside coupling, as well as for low loss, miniaturization and self-packaging. To further reduce the dielectric loss, the suspended substrate is cut out in specific pattern. The proposed dual-band power divider (DBPD) is analyzed using the even- /odd- mode method, the S-parameters are derived, and the design procedure is exhibited. For verification, a DBPD prototype working at 2.45 / 5.13 GHz is implemented. The measured results agree well with the simulated ones. The two passbands are from 1.7 GHz to 3.1 GHz and from 4.6 GHz to 5.5 GHz, with fractional bandwidth (FBW) of 58.3% and 17.8%, respectively. The measured return loss and isolation are both better than 15 dB in both passbands.