Four-way Filtering Power Divider Research Articles

Exact synthesis of couple‐line based wideband four‐way filtering power divider with unequal power division

AbstractIn this paper, a coupled‐line‐based wideband four‐way filtering power divider (FPD) with unequal power division is presented. It is composed of three groups of coupled lines (CLs), four types of open‐ended stubs, and three kinds of resistors. By setting the CLs in each group with different parameters, unequal power distribution is obtained. Besides, open‐ended stubs with different characteristic impedances are inserted to each output port to generate two extra transmission zeros, at the same time maintaining good impedance matchings. Resistors are inserted to each group of the CLs to improve the isolations. By applying twice parity mode analysis, the exact synthesis of the proposed FPD is first derived. For demonstration, a prototype with power division ratio of 1:1.2:1.5:1.8 is designed and manufactured. Measurement results verified that more than 60% fractional bandwidth (FBW) is obtained under the criterion of 10 dB return loss and 10 dB isolation. Besides, the 3 dB passband FBWs for the four outputs reach 70% with high frequency selectivity and low insertion loss. And more than 15 dB out‐of‐band rejections are achieved for both the lower and upper stopbands.

A New Triple-Band Four-Way Filtering Power Divider With Highly Improved Performance

This letter presents a new triple-band four-way filtering power divider (FPD) with greatly improved frequency selectivity and in-band isolation. By elaborately developing a multi-port multi-mode topology between four identical multi-mode resonators and feedlines, a triple-band four-way FPD is attained. In order to validate the feasibility of the proposal, one prototype is designed, fabricated, and measured. Both the simulated and measured results of the designed FPD are provided with a good agreement. Results indicate that this triple-band four-way FPD exhibits not only sharp selective filtering performance, but also satisfactory port-to-port isolations.

Compact HMSIW four‐way filtering power divider with pre‐defined division ratio

A novel and simple design approach of compact four-way filtering power divider (FPD) using half-mode substrate integrated waveguide (HMSIW) cavity is investigated in this letter. The pre-defined power division ratio of the four outputs is obtained by adjusting the external quality factor (Qe) of each output port, while the total output Qe is equal to the input Qe. The four outputs are loaded to a single HMSIW resonator, achieving a compact size. Meanwhile, both bandpass response and power division can be designed independently. For demonstration, a prototype with pre-defined power division ratio of 1:3:3:1 is designed, fabricated, and measured. The measured results show that the FPD centered at 4.88 GHz owns a 3-dB fractional bandwidth (FBW) of 11.3%. The insertion loss of the passband is about 1.4 dB and the return loss is better than 17 dB, meanwhile the phase differences of in-phase four outputs are all within 5° from 4.61 to 5.16 GHz. Good agreement is observed between the simulated and measured results.

Synthesis of miniaturized wideband four‐way filtering power divider consisting of unequal‐width three‐coupled‐lines

A miniaturized wideband four-way filtering power divider (FPD) is presented in this article. It is composed of unequal-width three-coupled-lines (TCLs), stepped-impedance open-circuited stubs, and isolation resistors. By using two groups of the unequal-width TCLs and the stepped-impedance open-circuited stubs, size reduced four-way FPD with wideband filtering responses and out-of-band rejection is realized. Besides, good output ports matching and isolation are obtained by inserting two types of air-bridge resistors. In the theoretical analysis section, the impedance matrix of the unequal-width TCL is introduced, for the first time, and rigorous closed-form design equations for the proposed FPD are also derived. Moreover, the methodology for computer-aided design is given based on the design equations. For demonstration, a prototype operating at 1.5 GHz is designed, fabricated, and measured. The measured results validate the 80% bandwidth with more than 17 dB out-of-band rejection, more than 14 dB isolation and more than 15 dB return loss at all output ports. Compare with the reported four-way FPD with similar bandwidth, a size reduction of 74% is obtained.

Miniaturised wide tuning‐range four‐way quasi‐lumped‐element filtering power divider

This Letter presents a miniaturised wide tuning-range four-way filtering power divider (FPD). It is mainly developed by integrating a co-shared varactor-loaded quasi-lumped-element dual-mode resonator and an isolation resistor, achieving a wide tuning power division ratio (PDR) and centre frequency (CF) simultaneously. The presented tunable four-way FPD stands out from those in the literature, by both its improved performance (wider tuning range for PDR and CF with nice isolation and matching) and ultra-compact design layout. To validate the design concept, a reconfigurable prototype is designed, fabricated, and tested. Measured results will coincide with the simulated ones.

Analysis and design of compact four‐way single‐ and dual‐band filtering power dividers on a new adjustable multi‐mode topology

Four-way single-/dual-band operation integrated filtering power divider (FPD) with new design topology is presented in this study. For either single- or dual-passband response, it involves only one same-type pair of multi-mode resonators and three isolation resistors, comparing with other existing four-way FPDs. By adopting the even-/odd-mode analysis method to flexibly control the resonant modes of the designed resonator and select isolation resistances, both single- and dual-band four-way filtering power division responses are specified and derived with the same one configuration. The proposed four-way FPD designs stand out from the reported ones by both nice operation performance, flexible topology with reduced number of resonators, and no additional feeding network at input port. For demonstration, two prototypes for four-way single- and dual-band FPDs are implemented following the given design procedure, respectively. Both simulated and measured results are exhibited to verify the theoretical design concept.

Novel Switchable Filtering Circuit With Function Reconfigurability Between SPQT Filtering Switch and Four-Way Filtering Power Divider

In this article, we propose a circuit model for designing the switchable filtering circuit with reconfigurable functions between a single-pole quad-throw (SPQT) filtering switch (State 1) and a four-way filtering power divider (State 2) without additional switchable impedance matching network (IMN). The proposed circuit model can be utilized as the feeding network of a switchable directive and omni-directional antenna system to eliminate the omni-directional antenna in conventional solutions to reduce the size and cost. It consists of four filter channels with a common port. In State 1, it works as a SPQT filtering switch, where only one channel is turned on to realize good filtering responses and the impedances at the other three channels are adapted to infinity to realize high isolation. The four channels are turned on simultaneously in State 2 to work as a four-way filtering power divider, and the input impedance of the common port is the same as that in State 1. Thus, a switchable IMN is not required for port matching when switching between the two states. Transmission zeros are generated to enhance the skirt selectivity. For verification, the filtering circuit is constructed using high-$Q$ coaxial resonators. Experimental results show excellent performance in both states acting as a SPQT filtering switch and a four-way filtering power divider.

Wideband Four-Way Filtering Power Divider With Sharp Selectivity and High Isolation Using Coshared Multi-Mode Resonators

This letter presents an alternative fusion-design of a wideband four-way filtering power divider (FPD). A coshared coupling topology is proposed by embedding one pair of multi-mode resonators (MMRs) and three isolated resistors, bringing out wide power division band, decent frequency selectivity, and high in-band isolation. In comparison with other reported ones, the presented four-way FPD stands out not only by its favorable operation performance but also flexible topology that can also be easily extended to other multi-way multi-mode FPD designs and competitive size with a reduced number of resonators. A prototype is implemented to validate the design concept and method. Simulated results coincide well with the measured ones, verifying the theoretical design equations.

Four-Way Filtering Power Divider Using SIW and Eighth-Mode SIW Cavities With Ultrawide Out-of-Band Rejection

A four-way filtering power divider (PD) based on a substrate-integrated waveguide (SIW) is presented. This structure is composed of two layers of the dielectric substrate. The eighth-mode SIW (EMSIW) technique is used to make four cavities in the upper substrate. In addition, an SIW cavity is provided in the lower substrate. To achieve an efficient transition between the two layers, four rectangular slots are etched on the middle metal planes. A circular slot is etched on the top metal layer of the EMSIW cavities to suppress the higher operating modes. To prove the validity, a four-way PD with a second-order bandpass filtering response is designed and fabricated. The measured results show that the PD achieves an insertion loss of 1.3 dB at 3.5 GHz, a return loss of higher than 17 dB, a 3-dB fractional bandwidth of 7.75%, and an out-of-band rejection of greater than 26 dB from 3.92 to 16.5 GHz. The results show that this PD has the advantages of compact size, high selectivity, and ultrawide out-of-band rejection.

Design of wideband four‐way filtering power divider based on SIW loaded square patch resonator

A new design of wideband four-way filtering power divider (FPD) based on substrate-integrated waveguide (SIW) loaded square patch resonator is presented. The wideband operation is realised by utilising the TM 20 mode of the patch and the TE 110 mode of the SIW cavity resonator. Afterwards, the selectivity is obtained by adding four open-ended coupling lines to each side of the square patch. Besides, an extra isolation network is introduced between each output port. To verify the design concept, a prototype of the proposed FPD operating at 3.55 GHz with a fractional bandwidth of 21.3% is fabricated and measured. Results indicate that the input return loss is >10 dB and the insertion loss is 0.3 dB and 3°, respectively. Both simulated and measured results are in good agreement.

Microstrip Four-Way Reconfigurable Single/Dual/Wideband Filtering Power Divider With Tunable Frequency, Bandwidth, and PDR

In this paper, a microstrip reconfigurable four-way filtering power divider (FPD) with tunable center frequency (CF), bandwidth (BW), and power division ratio (PDR) is presented. A novel coupling scheme is proposed based on four stub-loaded quad-mode resonators (SL-QMRs), two three-line coupled structures, and two quarter-wavelength transformers, which can achieve tunable CF, BW, PDR, and wide isolation BW. Switchable single/dual/wideband filtering response and the CF and BW of a dual-band FPD can be tuned by controlling the varactor diodes loaded onto the open-ends of SL-QMRs. Meanwhile, the PDR is controlled by varying the coupling strength between the center line and sidelines of a three-line coupled structure. Compared with the conventional wideband FPDs, the capacitor loaded onto the parallel coupled line of two outputs enlarges the coupling, which can improve the return loss and, thus, relieve the limitation of the line space. Based on the coupled resonator theory, the parameters of the resonators and coupling sections are analytically determined. For the dual-band FPD, the measured results show that the 3-dB fractional BW of the lower passband can be tuned from 23.4% to 30.9%, while the one of the upper passbands is tuned from 12.3% to 18.5%. The measured CF for the upper passband can be tuned independently from 1.98 to 2.21 GHz, while the lower one remains fixed. Then, the measured PDR is controlled from 1:1:1:1 to 1:2:1:2. The proposed four-way reconfigurable FPD exhibits switchless single/dual/wideband filtering responses, high isolation level, wide isolation BW, and the control of CF, BW, and PDR.

Four-Way Microstrip Lumped-Element Reconfigurable Dual-Mode Filtering Power Divider

In this paper, a novel four-way microstrip lumped-element reconfigurable dual-mode filtering power divider (FPD) is proposed. The two operating states are a four-way FPD with constant return loss, and a stopband filter (SBF) with high isolation, respectively. This switchless two operating states can be switched by selecting appropriate voltage without using switches. The tunable filtering response of four-way FPD based on a novel coupling scheme is realized by two pairs of varactor-tuned LC resonators. The measured four-way FPD can be tuned from 0.98 to 2.08 GHz with return loss better than 18 dB. Its frequency tuning range (FTR) is 72%. The measured isolation is better than 19.5 dB from dc to 5.7 GHz. Apart from the bandpass FPD application, the proposed circuit can also be utilized as an SBF, which is different that of conventional SBF by tuning off diodes to obtain isolation. By staggering the resonant frequencies of four lumped-element resonators and decrease mutual coupling between resonators, an SBF with high isolation can be obtained between two nonadjacent ports. The measured isolation is better than 40 dB from dc to 6 GHz and better than 45 dB from 1.1 to 4.8 GHz. The proposed four-way reconfigurable dual-mode FPD exhibits wide isolation bandwidth and FTR, good return loss, high isolation level, and compact size.