Balanced Quasi-Elliptic-Type Combline Diplexer With Multiextracted-Pole Junction/Output Sections

Abstract

A class of coupled-multi-line quasi-elliptic-type balanced diplexer device with closely-spaced channels and its balanced coupling-routing-diagram formalism to simultaneously model its differential-and common-mode operation are reported. It employs third-order combline-type bandpass filters (BPFs) in its filtering channels, whose resonating lines are connected at one of their extremes to the symmetry plane of the balanced-circuit structure (i.e., virtual grounds for the differential mode), along with a multi-extracted-pole/coupled-multi-line dual-band BPF junction and single-band BPF output cells. In differential-mode operation, the dual-band BPF junction adds one in-band pole to each diplexer channel and three transmission zeros (TZs) to both channels, whereas the single-band BPF output cells incorporate one in-band pole and two TZs in their corresponding channels. In this manner, increased-selectivity differential-mode BPF transfer functions for the diplexer channels when compared to those of its third-order combline-type BPFs are obtained. Grounded resistors are connected at the symmetry plane of the balanced diplexer for all the resonating lines of the combline-type BPFs, which become detuned with regard to the poles associated to the dualband BPF junction and the single-band BPF output cells under common-mode excitation. This allows for high common-mode suppression levels in wide spectral ranges to be realized for both channels while maintaining the same TZs as in differentialmode operation. For practical-validation purposes, a 1.6/1.8-GHz microstrip prototype is manufactured and tested.

Compact Multilayered Balanced-to-Balanced Dual- and Tri-Band Diplexers Based on Magnetically Coupled Open-Loop Resonators

“…For this reason, multiband differential-mode (DM) devices have attracted a lot of attention in recent years [1]- [16]. Diplexers are a type of devices on which researchers have recently focused their attention [17]- [31]. Among them, references [28]- [31] deal with planar dual-band balanced diplexers (DB-BDs).…”

A diplexer with direct coupled resonant junction

“…With the help of a slot coupling technique, it has contributed in designing a highly compact dual‐band filtering antenna where the resonator and the antenna were coupled back to back 5 also in designing of duplexing antenna using slot coupling 6,7 . In diplexers, it has been used as a frequency distributor to service two channel filters leading to improved frequency response and miniaturization 8‐13 . Using the dual mode resonators as a distributor in diplexer designs has been popular over the years as it also contributes to the filtering poles of the individual channels.…”

Compact balanced diplexer based on hairpin split ring resonators with high isolation performance

“…Recently, with the development of microwave technology, balanced circuits have been widely used owing to the better performance in terms of SNR and EM interference immunity. As an important front-end device in modern communications, the research on balanced diplexers is of great importance [21][22][23][24][25][26][27][28][29][30][31][32][33]. In [27], the SRR is used to design the balanced diplexer combined with a balanced T-junction input port.…”