Balanced Filtering Power Divider based on Odd-mode Hybrid Microstrip and Slotline Spoof Surface Plasmon Polaritons

Abstract

In this paper, an ultra-wideband balanced filtering power divider (B-FPD) with high common mode (CM) suppression level is proposed. The B-FPD is designed based on the odd mode spoof surface plasmon polaritons (SSPPs), which are constructed by the hybrid folded microstrip and slotline (HFMS) structure. Firstly, the dispersion characteristic and electric field distribution of the HFMS SSPP unit cell are investigated, which can decrease the upper cut-off frequency for size reduction of nearly 50%. Next, an equal balanced power divider with low cut-off frequency is proposed based on the microstrip-to-slotline transition structure and slotline Y-junction. Then, the balanced power divider is used to excite the odd mode of HFMS SSPP structure. An equal B-FPD with center frequency of 4.0 GHz is implemented, and the 3-dB bandwidth covers 0.9 to 7.0 GHz. Finally, the B-FPD with advantages of high CM suppression level and compact size is fabricated and measured.

Broadband Balanced-to-Balanced Filtering Power Divider Using HMSIW-SSPP Transmission Line

“…The proposed BTB FPD based on the HMSIW-SSPP transmission line has a broader operating bandwidth than the BTB FPDs in [ 2 , 3 , 4 , 6 , 7 , 8 , 9 ], and it also possesses independent control of the passband’s lower and upper cut-off frequencies, making obtaining the desired frequency response easier. Although the SSPP BTB FPD in [ 5 ] achieves a 152% FBW and compactness, this proposed design has better IL, RL, and isolation than that of [ 5 ]. The proposed BTB FPD’s DM isolation between output ports approaches the BTB FPDs in [ 8 , 9 ], but within a broader range.…”

“…The proposed BTB FPD’s DM isolation between output ports approaches the BTB FPDs in [ 8 , 9 ], but within a broader range. This design features a better IL than that of BTB FPDs in [ 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 ].…”

“…The proposed BTB FPD's DM isolation between output ports approaches the BTB FPDs in [8,9], but within a broader range. This design features a better IL than that of BTB FPDs in [2][3][4][5][6][7][8][9]. Table 3 shows the performance of the proposed BTB FPD and other reported BTB FPDs.…”

“…The values and positions of the isolation resistors can be obtained based on Formulas (1)-( 6) and propagation constants of each unit cell calculated by eigenmode analysis. (5) Improvement in CM suppression between output ports. The initial length of output port DGS is set to three times the width of the microstrip line, and then it is further optimized to make |S cc32 | approach −30 dB.…”

“…However, these designs suffer from limitations in power capacity and increased losses at higher frequencies. Recently, an ultra-wideband BTB FPD with a high CM suppression level has been proposed based on hybrid microstrip and slotline spoof surface plasmon polariton (SSPP) structure [ 5 ], since the SSPP features unique characteristics, including strong field confinement, controllable dispersion, slow-wave effect, and lowpass characteristics. However, the SSPP BTB FPD in [ 5 ] also exhibits limitations of power and loss at higher frequencies.…”