This article proposes the synthesis design method of the dual-band differential phase shifters with independent filtering passbands and predetermined phase shifts. The filtering unit of the proposed ...phase shifter adopts a simple branch-line structure, which possesses its characteristics of controllable dual-band frequency ratios and bandwidths. Meanwhile, the Schiffman phase alignment element holds the capability of achieving different predetermined phase shifts in dual band. In our design, dual-mode resonator and dual-mode J-inverter models for the filtering units are equivalently established, and the amplitude and phase closed-form formulas for the proposed dual-band phase shifter are further numerically obtained for the first time. This proposed work features new synthesis method, integrated higher order filtering response with two independently prescribed bandwidths, and concurrent predetermined dual-band phase shifts. Design procedures are provided in detail for a quick design. Finally, two dual-band phase shifters with different frequency ratios and phase shifts are designed and demonstrated. The experimental and measured results match well.
In this paper, a class of balanced wideband phase shifters with good filtering property and common-mode (CM) suppression is proposed, synthetically designed, and implemented. Unlike the conventional ...coupled-line reference branch one, the proposed balanced phase shifter has its T-shaped structure in both of main and reference branches, so as to achieve superior passband selectivity and CM rejection simultaneously. The synthesis method is then presented to design the proposed balanced wideband phase shifters with the prescribed phase shift value, passband ripple, maximum phase deviation, and fabricated bandwidth. The 30°, 45°, 60°, 75°, and 90° balanced phase shifters are theoretically designed and demonstrated. To validate the design method, two prototypes with different fractional bandwidths (FBWs) and phase shift values (Case 1: FBW = 66.7%, typical phase shift value is 30°; Case 2: FBW = 55.6%, typical phase shift value is 90°) are designed, fabricated, and measured. The synthesized, simulated, and measured results are found in good agreement with each other.
This letter proposes a new design method of dual-band filtering differential phase shifter using cascaded wideband phase shifter and bandstop network. After cascading the bandstop network, the phase ...shift characteristic of the initial wideband filtering differential phase shifter remains unchanged, while its wide passband is divided into dual subpassbands. Compared with traditional dual-band-filter-based topology, the proposed cascaded one features the advantage of independently controlled phase and amplitude responses, and can achieve the same phase shifts in two passbands that conventional one cannot. For verification, a dual-band differential phase shifter with two same phase shifts of 90° is designed, fabricated, and measured. Simulated and measured results show good agreement.
In this article, two coplanar-strip (CPS) wideband balanced bandpass filters with intrinsic common-mode (CM) suppression are proposed based on shunt-stub structures. As previously reported with ...higher integration and greater flexibility, the double-sided shunt-stub structures could make sufficient use of various transmission lines (TLs), such as double-sided parallel-strip line (DSPSL), microstrip line (MSL), and slot line (SL). Compared with its conventional dual circuit, the proposed structure herein is capable of realizing ideal CPS-based resonant characteristics without degraded performance. As such, a DSPSL-loaded CPS triple-mode resonator and a microstrip-to-CPS (MS-to-CPS) transition are developed as two distinctive double-sided shunt-stub element units. Meanwhile, their equivalent circuit models are generalized for analysis of these proposed shunt-stub units and the corresponding synthesis design is further theoretically derived. For experimental verification, one fifth-order and one seventh-order balanced filters are designed, fabricated, and measured. It has been well demonstrated that both the wideband differential-mode (DM) filtering property and intrinsic CM suppression are satisfactorily achieved at the same time, with a certain range of available bandwidths.
This brief proposes a class of filtering differential phase shifters with independent phase shift response and effective harmonic suppression. Different from the traditional single-mode resonator ...topology, dual-mode resonators are utilized here for single-band phase shifters. By adjusting its impedance values, the harmonics can be aligned without affecting its in-band filtering and phase shift characteristics. Furthermore, scaled line transformation are furtherly introduced for extended stopband bandwidth. By combining the dual-mode resonator with its scaled lines, the proposed phase shifters can readily realize desired phase shift response and independently suppressed harmonics. A generalized circuit model is established for closed-form synthesis design of the presented phase shifters with any arbitrary odd order. In the end, the <inline-formula> <tex-math notation="LaTeX">3^{\mathrm{ rd}} </tex-math></inline-formula>- and <inline-formula> <tex-math notation="LaTeX">5^{\mathrm{ th}} </tex-math></inline-formula>-order filtering differential phase shifters are designed and fabricated for verification. It is found that the simulated and measured results are in good agreement.
In this paper, two types of coplanar stripline (CPS)-based multimode stepped-impedance resonators are proposed for exploration of wideband balanced filters with intrinsic common-mode (CM) ...suppression. Such CPS multimode resonators (MMRs) can be readily terminated with either a pair of open- or short-circuited ends with no need of via holes. With resorting to a proper impedance ratio, the first three modes of each MMR are assembled to construct a wide differential-mode (DM) passband. Afterwards, two distinctive broadside-coupled sections are further investigated based on their open- and short-ended circuit models, respectively. Characteristic impedances and effective dielectric constants can be adequately obtained by virtue of an efficient quasi-static approach under the odd- and the even-mode operations. As such, two types of CPS-MMR-based bandpass filters each with five transmission poles are synthetically designed. For experimental validation, the proposed balanced filters are finally fabricated and measured with the help of two identical pairs of balanced-to-balanced microstrip-to-CPS transitions. Theoretical, simulated, and measured results are found in reasonable agreement with each other with/without the transitions, thus demonstrating that the proposed CPS-based MMRs are well characterized with the wideband DM transmission and intrinsic CM suppression.
This letter proposes a wideband filtering differential phase shifter with enhanced harmonic suppression. Through the original transmission line model, the numerical relationship between the ...prescribed amplitude/phase response and the initial design parameters can be readily established. Then the simple transformation from the transmission line to its T-type lowpass network is utilized to suppress the harmonics efficiently with almost the same in-band phase shift response. For demonstration, a prototype is designed and fabricated, the proposed filtering phase shifter features enhanced harmonic suppression up to <inline-formula> <tex-math notation="LaTeX">3.5f_{0} </tex-math></inline-formula> and an enhanced suppression level of 33.5 dB.
In this article, a class of improved Schiffman phase shifters with two C-section coupled lines separately operating in the first and second phase periods is presented and analyzed. Theoretical model ...and closed-form synthesis formulae are utilized to analyze the phase performances of the proposed phase shifters, which reveals significant differences compared to the phase shifters solely operating in the first or second phase period. Compared to the traditional counterparts, the proposed phase shifters can achieve a larger phase shift value and a wider phase shift range at the same impedance ratio. Moreover, under the same impedance ratio, the phase shifter can obtain wider phase shift bandwidth. These features are believed to be very useful in the limitedly realizable coupling strength for a wide phase shift range case. Finally, two sets of comparative experiments, including the operations in the first phase period, second phase period, and the proposed type, are designed and fabricated to validate the proposed approach. The simulated and measured results agree well with the theory and achieve a 33.6% (36.7%) increase in phase shift bandwidth when the phase shift value is 90° (150°) under the impedance ratio of 1.5822 (2.0312).
This communication proposes a wideband low-profile circularly polarized patch antenna based on a broadband 90° modified Schiffman phase shifter and a meandering L-shaped microstrip feed. The whole ...antenna consists of a broadband hybrid feeding network and a circular patch radiator. The hybrid network has two branches that operate in the first and second Schiffman periods, and thus can achieve 113% 10 dB return loss bandwidth and 75% phase shift bandwidth within 90°± 4.6° under a relaxed coupling strength of 1.58. To reduce the profile, the planar microstrip L-shaped feeding probe is properly meandered, which provides not only broadband impedance matching, but also an extra degree of freedom in the reduction of cross polarization, thus achieving a wide axial ratio (AR) bandwidth. Simulated and measured results show that the antenna has indeed achieved a low profile (<inline-formula> <tex-math notation="LaTeX">0.05~\lambda _{0} </tex-math></inline-formula>) with 50.5% impedance bandwidth, 47.8%AR bandwidth, and 34% gain bandwidth (>3 dBi).
In this article, a class of microstrip-to-coplanar strip (MS-to-CPS) transitions with wideband balanced-type topologies, efficient synthesis design approach, and well-verified experimental ...de-embedding are proposed and designed. By virtue of the electromagnetic field conversion along the transitions, the unwanted common-mode (CM) signal could be intrinsically rejected while the differential-mode (DM) counterpart is capable of being converted through a very wideband. In this context, equivalent circuits of such transitions under DM operation are first developed and synthesis design is derived so as to determine each characteristic impedance in these transmission-line (TL) models. Propagation parameters for various CPS lines with varied physical dimensions are then investigated. Experimental de-embedding procedure is described and executed to extract the fundamental responses of a single transition inherently. As a result, a third-order and two different fifth-order MS-to-CPS transitions with respective fractional bandwidth (FBW) of 100%/111%/111% are finally synthesized, designed, fabricated, and measured. Measured results agree well with the theoretical, simulated, and extracted ones, strongly demonstrating and verifying that these proposed transitions feature indeed not only the intrinsic CM suppression but also the wideband DM filtering performances.
