Schiffman Phase Shifter Research Articles

Quadrature Wilkinson power divider using cross-type short-circuited shunt stub for good amplitude and phase balance

This paper introduces a new design of a quadrature 3-dB power splitter using a quadrature Wilkinson power divider and a cross-type short-circuited shunt stub for printed circuit board (PCB) circuit design. For 3-dB power splitting and a relative 90° phase difference, several types of quadrature 3-dB power splitters are commonly used in RF and microwave applications, including Lange coupler, directional coupler, branch-line coupler, and quadrature Wilkinson power dividers. Among them, quadrature Wilkinson power dividers often utilize a Schiffman phase shifter and λ/4 short-circuited shunt stubs for compensation circuit.In this paper, the aforementioned schemes have been evaluated by image rejection ratio (IRR) bandwidth (BW) related to amplitude and phase imbalance property. The new design of the quadrature Wilkinson power divider adopting the proposed cross-type short-circuited shunt stub offers superior −25-dB IRR BW compared with other quadrature 3-dB power splitters in PCB fabrication. In measurement, the proposed quadrature Wilkinson power divider provided a −25-dB IRR BW of 3.50 GHz, operating at a center frequency of 9.5 GHz. The designed power splitter offered an operating frequency of 2.64 GHz, satisfying −25-dB IRR BW, 10-dB impedance BWs, and 20-dB isolation BW.

Balanced Wideband Quasi-Schiffman Phase Shifters Based on Slotlines

This brief presents a quasi-design about balanced wideband Schiffman phase shifters based on slotlines, which can achieve phase shift with relatively small phase equiripple and high common mode (CM) rejection. The proposed balanced phase shifters are mainly composed of a microstrip/slotline transition structure and a C-section coupling slotline. C-section coupling slotline consisting of two long parallel coupling slotlines and two short parallel coupling slotline can achieve the phase shift function. The microstrip/slotline transition structure is employed as a balanced port, so that the differential mode (DM) response and CM one are independent of each other. Different from the traditional Schiffman phase shifter: two methods are used to compensate the different phase velocity between the odd and even modes. In order to decrease the DM transmission loss, sandwich structure is also employed in this design. To the best of authors’ knowledge, the balanced wideband Schiffman phase shifter based on slotline may be the first ever reported. Finally, 45°, 90° and 180° phase shifters with a central frequency at 2.37 GHz are achieved to verify the design method. The measured results agree well with the simulation.

Ultrawideband Schiffman Phase Shifter Designed With Deep Neural Networks

This article presents a novel method for the forward modeling and inverse design of a class of Schiffman phase shifters using deep neural networks (DNNs). Since DNNs are capable of mapping the highly nonlinear correlations between inputs and outputs, we constructed a fully connected DNN to predict the electromagnetic (EM) responses of Schiffman phase shifters given their physical dimensions. Based on this fast and accurate modeling tool, a cascaded inverse design DNN was then built and trained to achieve instant on-demand phase shifter designs. This approach is versatile and can be easily modified to accomplish different design goals. To demonstrate its efficacy, we trained two DNNs to realize Schiffman phase shifter designs with different bandwidths (40% and 60%) and arbitrary phase shift targets (0°–180°). Simulation results and experimental verifications substantiate that their performances are comparable with the state-of-the-art designs. Moreover, we discussed the proposed methods’ potential in dealing with design tasks that are nonintuitive and beyond the scope of the existing approaches. We envision that this DNN approach can be extended to the design of various EM components including but not limited to antennas, filters, power dividers, and frequency selective surfaces (FSS).

Multiband Ambient RF Energy Harvester with High Gain Wideband Circularly Polarized Antenna toward Self-Powered Wireless Sensors.

In this work toward a sustainable operation of a self-powered wireless sensor, we investigated a multiband Wi-Fi/3G/4G/5G energy harvester based on a novel wideband circularly polarized antenna, a quadplexer, and rectifiers at four corresponding bands. This proposed antenna consisted of four sequentially rotated dual-dipoles, fed by a hybrid feeding network with equal amplitude and an incremental 90° phase delay. The feeding network was composed of three Wilkinson power dividers and Schiffman phase shifters. Based on the sequential rotation method, the antenna obtained a −10 dB reflection coefficient bandwidth of 71.2% from 1.4 GHz to 2.95 GHz and a 3 dB axial ratio (AR) bandwidth of 63.6%, from 1.5 GHz to 2.9 GHz. In addition, this antenna gain was higher than 6 dBi in a wide bandwidth from 1.65 GHz to 2.8 GHz, whereas the peak gain was 9.9 dBi. The quad-band rectifier yielded the maximum AC–DC conversion efficiency of 1.8 GHz and was 60% at −1 dBm input power, 2.1 GHz was 55% at 0 dBm, 2.45 GHz was 55% at −1 dBm, and 2.6 GHz was 54% at 0.5 dBm, respectively. The maximum RF–DC conversion efficiency using the wideband circularly polarized antenna was 27%, 26%, 25.5%, and 27.5% at −6 dBm of input power, respectively.

Broadband planar 90 degrees loaded-stub phase shifter

The differential phase shifter is an interesting four-port passive microwave network composed of two separate lines, the main line and the reference line, and providing stable phase difference between the two output signals over the specified bandwidth of interest. The most common differential phase shifter is the coupled-line Schiffman phase shifter. In this paper, a novel 90 degrees differential microstrip phase shifter configuration employing a half wavelength transmission line loaded with three open stubs is presented, the proposed design could achieve excellent performance with low phase variation over a wide bandwidth compared to the standard Schiffman phase shifter. The simulated results accomplished with the use of CST Microwave Studio and advanced design system (ADS), were found to be in good agreement and have shown that the proposed loaded-stub phase shifter achieved less than 1.1 dB insertion loss, greater than 13 dB return loss and constant 90±5 degrees phase shift over an 89 percent bandwidth.

Wideband Low-Profile Circularly Polarized Patch Antenna Using 90° Modified Schiffman Phase Shifter and Meandering Microstrip Feed

This communication proposes a wideband low-profile circularly polarized patch antenna based on a broadband 900 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 900±4.60 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 (0.05 λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> ) with 50.5% impedance bandwidth, 47.8%AR bandwidth , and 34% gain bandwidth (>3 dBi).

Designing of Miniaturized 4 × 4 Butler Matrix Using Coupled Line Coupler and Schiffman Phase Shifter

A novel and miniaturized 4 × 4 butler matrix (BM) is proposed in this work. This proposed butler matrix is designed with four 3 dB quadrature (90°) forward wave coupled line coupler (FWCC) and two 45° Schiffman phase shifter. This BM is designed at center frequency of 2.4 GHz using FR4 substrate. The crossover of this BM has been replaced with a 0 dB FWCC. The performances of all couplers have been improved with the help of defected ground structures (DGS). Two C-shape and one I-shape DGSs are etched at the ground plane of each coupler, and two C-shape and one dumbbell shape DGSs are etched at the ground plane of 0 dB crossover which enhance the performance of the BM. This proposed BM provides a maximum bandwidth of 120 MHz at each port and occupies a total area of 0.677λ0 (84.74 mm) × 0.612λ0 (76.56 mm).

Wideband filtering balun power dividers using modified Schiffman phase shifter

Two novel wideband bandpass filtering balun power dividers using modified Schiffman phase shifter are proposed in this article. Two types of wideband Wilkinson power dividers are adopted, respectively, in the two structures for wide passband. The Schiffman phase shifters are used in the structures for realizing 180° phase shift between output ports modified by connecting each of them with a short-ended stub for weak coupling coefficient. In addition, two transmission zeros are realized by an open-ended stub connected in parallel at the input port to realize the filtering characteristic. To verify the proposed structures, two wideband bandpass filtering balun power dividers (εr = 3.66，h = 0.762 mm, tanδ = 0.004) centering at 2GHz are designed and fabricated. The simulated and measured results are discussed.

Design of compact wideband 90° Schiffman phase shifter incorporating CSRR

ABSTRACTIn this work, a compact and wideband Schiffman phase shifter is proposed using a microstrip transmission line. This proposed phase shifter incorporates a rectangular complementary split-ring resonator (CSRR) and two open stubs. It is designed to get a phase shift of 90° with ±5° phase imbalance for the frequency range of 1.47–3.52 GHz. It shows a fractional bandwidth of 85.41% at the center frequency of 2.4 GHz. The proposed design occupied a total area of 0.067 λg2. The proposed structure is fabricated and validated, there is a good agreement between the simulated and measured results.

Schiffman Phase Shifters With Wide Phase Shift Range Under Operation of First and Second Phase Periods in a Coupled Line

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).

26 GHz phase shifters for multi-beam nolen matrix towards fifth generation (5G) technology

This paper presents the designs of phase shifters for multi-beam Nolen matrix towards the fifth generation (5G) technology at 26 GHz. The low-cost, lightweight and compact size 0° and 45° loaded stubs and chamfered 90°, 135° and 180° Schiffman phase shifters are proposed at 26 GHz. An edge at a corner of the 50 Ω microstrip line Schiffman phase shifter is chamfered to reduce the excess capacitance and unwanted reflection. However, the Schiffman phase shifter topology is not relevant to be applied for the phase shifter less than 45° as it needs very small arc bending at 26 GHz. The stubs are loaded to the phase shifter in order to obtain electrical lengths, which are less than 45°. The proposed phase shifters provide return loss better than 10 dB, insertion loss of -0.97 dB and phase difference imbalance of ± 4.04° between 25.75GHz and 26.25 GHz. The Rogers RT/duroid 5880 substrate with dielectric constant of 2.2 and substrate thickness of 0.254 mm is implemented in the designs.

Design and Analysis of Schiffman Phase Shifter Under Operation of its Second Phase Period

In this paper, a new design concept of Schiffman phase shifters under the operation of the second phase period in frequency domain is presented and analyzed. By investigating phase properties of the C-section structure, we first find that its second phase period is another independent and distinctive working region for Schiffman phase shifter, in addition to its first phase period. In contrast to traditional counterparts working on the first phase period, which are suitable for small phase shift from 0° to 90°, the Schiffman phase shifters on the second phase period are suitable for the large phase shift from 90° to 180°. It is because of the opposite phase variation property that the electrical length of reference line gets shortened as the phase shift value increases. Compared with the first phase period, the second phase period can achieve wider phase shift bandwidth under the same coupling degree. This feature is believed to be very useful in the limited realizable coupling degree cases. In this context, the closed-form synthesis formulas of Schiffman phase shifter on the second phase period are presented. Meanwhile, detail theoretical analysis of the phase shift bandwidth and phase deviation is carried out. In final, two Schiffman phase shifters on the first and second phase periods are designed and fabricated to validate our proposed concept and approach in the experiment.

A Novel Feeding Network for Quadri-Polarization Antennas With Simultaneously Wide Impedance and Polarization Bandwidth

In this communication, a broadband feeding network for quadri-polarization antennas has been proposed. The feeding network is composed of several passive components, namely two Wilkinson power dividers, slow-wave transmission lines, Schiffman phase shifters, branchline hybrids, and a crossover. With a careful design of each component and an elaborate topology arrangement, the four output ports can transmit signals for antennas with four polarization states in a wideband, i.e., left-hand circular polarization, right-hand circular polarization, +450 and -450 linear polarization. Two antenna implementations based on such a feeding network have been given, and the measured results show that antennas have a bandwidth as wide as 22.7%, within which excellent input port impedance matching, port isolation, realized gain, and polarization purity are simultaneously achieved. The feeding network also has advantages such as completely switch-free, ease of fabrication and implementation, and flexibility for different types of antenna configurations.

Authors’ Reply to “Comments on ’Design of a Planar Dual-Band Power Divider With Arbitrary Power Division and a Wide Isolated Frequency Band”’

We greatly appreciate the comments on [1] by Sinha [2] . There are typos for [1, (1)-(3)] . The equations should be corrected as \begin{align*} A=&D=-\frac {Z_{o} -(Z_{e} +Z_{o} )\cos ^{2}\theta }{Z_{o} +(Z_{e} -Z_{o} )\cos ^{2}\theta } B=&\frac {jZ_{e} Z_{o} \sin 2\theta }{Z_{o} +(Z_{e} -Z_{o} )\cos ^{2}\theta } C=&\frac {j\sin 2\theta }{Z_{o} +(Z_{e} -Z_{o} )\cos ^{2}\theta }. \end{align*} Consequently, two connected Schiffman phase shifters are employed to provide a phase shift of 180° at $f_{0}$ . When operated within the first passband $f_{1}$ , the electrical length $\theta $ of each Schiffman phase shifter will be less than 90°. Therefore, with $\vert S_{11}\vert = 0$ and $\vert S_{21}\vert = 1$ , $Z_{e}$ and $Z_{o}$

A wideband quadrature power splitter covering 81.75% fractional bandwidth in single layer via‐less technology

ABSTRACTA novel 90° wideband quadrature power splitter configuration based on the contemporary use of a large band 3‐dB Wilkinson power divider combined with a 90 degrees Schiffman phase shifter is presented. The proposed approach is consistent with an implementation on a single layer, via‐less, low performance substrate, thus enabling simple fabrication and integration. The proposed solution leads to a balanced power splitting (±1.5 dB), a consistent phase shifting (90°±10°), and a good input matching (S11 ≤ −10 dB) from 2.3 GHz to 5.48 GHz, hence suitable for a wide range of applications, comprising IEEE 802.11 WiFi operation in both S and C band. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 59:142–145, 2017

Broadband Integrated &lt;inline-formula&gt; &lt;tex-math notation="LaTeX"&gt;$8 \times 8$ &lt;/tex-math&gt; &lt;/inline-formula&gt; Butler Matrix Utilizing Quadrature Couplers and Schiffman Phase Shifters for Multibeam Antennas With Broadside Beam

A novel realization of a broadband $8 \times 8$ Butler matrix having phase progressions 0°, ±45°, ±90°, ±135°, and 180° has been proposed. The presented network is composed of coupled-line 3-dB/90° directional couplers and Schiffman phase shifters that ensure its broadband amplitude and phase characteristics. The proposed solution allows for a fully planar realization without any interlayer connections, which has been achieved by both rearrangement of the matrix layout and realization of the selected crossovers as tandem connections of quadrature directional couplers. The proposed concept has been verified experimentally by the design of a Butler matrix operating within 2.5–3.5 GHz and applied in a multibeam antenna array with broadside beam.

An ANN-Based Synthesis Model for Parallel Coupled Microstrip Lines with Floating Ground-Plane Conductor and Its Applications

To directly obtain physical dimensions of parallel coupled microstrip lines with a floating ground-plane conductor (PCMLFGPC), an accurate synthesis model based on an artificial neural network (ANN) is proposed. The synthesis model is validated by using the conformal mapping technique (CMT) analysis contours. Using the synthesis model and the CMT analysis, the PCMLFGPC having equal even- and odd-mode phase velocities can be obtained by adjusting the width of the floating ground-plane conductor. Applying the method, a 7 dB coupler with the measured isolation better than 27 dB across a wide bandwidth (more than 120%), a 90° Schiffman phase shifter with phase deviation ±2.5° and return loss more than 17.5 dB covering 63.4% bandwidth, and a bandpass filter with completely eliminated second-order spurious band are implemented. The performances of the current designs are superior to those of the previous components configured with the PCMLFGPC.

An Innovative Ultra Wideband Microstrip Phase Shifter Based on the LANGE Coupler

The method presented in this paper is beased on coupled line in the standard schiffman phase shifters structure and replace it with lange coupler. To having a wider bandwidth, the stronger coupling is required. One way to achieve strong coupling is using of the parallel coupled lines that this property exist in the lange coupler. So this paper discusses the design of fixed broadband phase shifter by using the lange coupler and a novel phase shifters will be introduced according to the standard schiffman phase shifters. Finally optimal parameters to achieve the desired performance will be shown.

Design of a broadband circularly polarized rectenna for microwave power transmission

This article presents a broadband circularly polarized (CP) rectifying antenna (rectenna) for microwave power transmission at 4.2–7.6 GHz, comprising a broadband CP antenna, and a rectifier circuit. The antenna consists of a standard Schiffman phase shifter and a pair of orthogonally positioned linearly polarized slot antennas with equal radiation strength. The rectifier circuit is composed of a microwave Si Schottky detector diode (HSMS-2862), a low-pass filter, a load resistor, and a ripple capacitor. Output dc voltage of 1.98 V over a 680 Ω load resistance and the maximum microwave-to-dc conversion efficiency of 81.6 % were measured when 34 dBm microwave power was transmitted at 5.6 GHz over a distance of 50 cm. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:702–706, 2015

Design of a Planar Dual-Band Power Divider With Arbitrary Power Division and a Wide Isolated Frequency Band

A microstrip dual-band Gysel power divider with arbitrary power division is proposed. In order to generate two frequency bands simultaneously, two Schiffman phase shifters are adopted. Moreover, these frequency bands with arbitrary power ratio between two output ports can be controlled by the transmission lines' impedances Z1 and Z2. In addition, with two π-shaped transmission lines series connected at two output ports, there is prominent rejection between two passbands and a wide isolated frequency band between two output ports. Furthermore, two dual-band power dividers are developed to verify the proposed design.