Reflection-type Phase Shifter Research Articles

Low‐cost and easy‐to‐embed 7‐bit 360° phase shifter with transitions for large‐scale phased arrays

AbstractIn this letter, a low‐cost and easy‐to‐embed 7‐bit 360° phase shifter with transitions is presented for applications to beamforming in the large‐scale phased array. In the proposed 360° phase shifter, the topology of the reflection‐type phase shifter (RTPS) is employed, composed of a 3‐dB branchline coupler terminated with two tunable parallel L–C loads. First, a two‐step phase extraction process for RTPS is applied to design the RTPS rapidly with competitive performance, including 360° phase range and low insertion loss. A huge amount of parameter sweep is reduced in the design and test. Meanwhile, the parameter of inductors in the tunable loads is investigated effectively, to achieve the minimal phase step. Second, aiming at the enhanced performance of beamforming and improved flexibility of integration, the stripline is adopted in the design of the phase shifter, avoiding the interference on antenna radiation effectively. To facilitate the integration with antenna and radio frequency connectors of the input and output signals, a stripline‐to‐microstrip line transition with electromagnetic bandgap structures is adopted. By this means, the complexity and cost of fabrication are decreased. Finally, fabricated in the low‐cost printed circuit board technology, our proof‐of‐concept design operated from 2.4 to 2.5 GHz is measured and achieves a 386.8° phase shift range with an insertion loss of 2.21 ± 0.82 dB at 2.45 GHz.

Mechanically Controlled, Wide-Angle Scanning, Series-Fed Antenna Array With Low Profile for High-Power Radar Systems

This paper presents the design and implementation of a mechanically-controlled, series-fed antenna array featuring wide-angle beamsteering at the X-band. A theoretical model of a series-fed array, including phase shifters inserted between consecutive elements, is initially developed to derive design rules and gain insight into crucial performance trade-offs. Subsequently, a mechanically-controlled, reflection-type phase shifter consisting of a branch line coupler and two Pi-network reflective loads is presented. A movable metallic overlay tunes the impedance of the reflective loads, thus effectively modifying the output phase. While requiring a minimal linear displacement of only 0.06λ0, this topology provides a maximum phase shift of 300° with an average insertion loss of 1 dB and is exploited for synthesizing a series-fed patch array. Based on simulations and measurements, the proposed antenna offers an almost constant realized gain of about 15 dBi within a wide scanning range of ±50°, and the side lobe level is better than -12 dB. The average total efficiency is 50%, and the cross-polarization levels are at least 11 dB below the maximum realized gain. The main weaknesses are the narrow bandwidth of 2.5% and the slight beam squint as the frequency varies. The proposed design is ideal for radars due to its excellent performance and high power-handling capability.

Cascaded Reflection-Type Group Delay Controller With a Wideband Flat Group Delay

This letter presents a wideband group delay controller (GDC) based on cascaded reflection-type phase shifters (RTPSs). Frequency tunable resonators are used as the reflective loads of each phase shifter so that the phase shifter has a variable group delay resulting in a reflection-type GDC (RTGDC). Two RTGDCs with different types of reflective loads are cascaded to compensate for their group delay variation over frequency. The first and the second stage of the cascaded RTGDC are respectively in charge of the delay in low and high-frequency bands and the cascaded delay is flat over a wide bandwidth. The proposed cascaded RTGDC operates at 3.7 GHz over 200-MHz bandwidth. The measured group delay varies from 0.67 to 2.18 ns, which is a 1.51-ns group delay variation under 9.1% normalized group delay variation over the bandwidth. The return loss is over 18 dB and the insertion loss is 2.1 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\pm$</tex-math> </inline-formula> 1.3 dB at 3.7 GHz.

A Wideband 1-bit Reconfigurable Electromagnetic Surface for Monopulse Radar Applications

We present a wideband 1-bit reconfigurable electromagnetic surface (REMS) for monopulse radar applications at X-band. The proposed REMS element integrates a 1-bit reflection-type phase shifter controlled by a PIN diode. By altering the working states of the PIN diode, well-defined beam scanning is obtained. Furthermore, selecting different feeding states can realize the sum (Σ) and difference (Δ) patterns. The key design issues, including element modeling, coding design, and feed optimization, are studied to obtain good Σ and Δ beam performance. Experimental results show that REMS achieves a high gain of 23.3 dBi, a low sidelobe level of -15 dB, and a low null depth of -30 dB. The wide-angle monopulse beam-scanning up to ±60° is obtained. The gain bandwidth of -3 dB ranges from 9.35 to 11.75 GHz, with a relative bandwidth of 22.75%. Thus, the proposed multi-feed REMS brings new freedom for the Σ and Δ beam scanning, which provides wide application prospects for the monopulse radar system.

Compact Single-Unit Two-Bit Reflection-Type Phase Shifters with Large Phase Shift Range

Multi-bit phase shifters are typically implemented by cascading multiple phase-shifting units, therefore incurring large dimensions and higher insertion losses. This paper presents highly compact single-unit two-bit reflection-type phase shifters (SUTBRTPSs), with large phase shifts range and lower insertion loss by using only one 3-dB hybrid coupler, unlike traditional multi-bit reflection-type phase shifters. To achieve this, two identical dual-voltage controlled reactance blocks (DVCRBs) are loaded to the 3-dB hybrid directional coupler at through and coupled ports, and 04 states of phase shifts are obtained between the input and isolated ports. Each DVCRB consists of 03 open-circuited transmission lines and switching p-i-n diodes and provides half of the required susceptance to achieve the desired phase shifts. Design theory is presented in detail, and for validation and demonstration, two typical SUTBRTPSs (0°/45°/90°/135° and 0°/22.5°/180°/202.5°) are designed, fabricated and measured. Being implemented in a single-unit structure, the proposed method yields highly compact dimensions of 0.44 λg × 0.46 λg and 0.54 λg × 0.46 λg, respectively. The simulation and measurements results are in good agreement and indicate maximum insertion losses of 1.7 and 2.1 dB with a return loss better than 20 dB and phase error of less than 1.5°.

120‐GHz 2‐bit reflection‐type phase shifter based on PIN diodes switched‐lines

AbstractIn this paper, a 2‐bit digital reflection‐type phase shifter (RTPS) working at 120 GHz is presented. It uses a compact coupled‐lines coupler with low insertion loss and high isolation over a wide bandwidth. The loads are made by a microstrip‐line loaded by three PN jonction separated by an intermediate region I (PIN) diodes whose states are tuned ON/OFF to obtain 90°, 180° and 270° phase shift relative to the reference (0°). Measurement results show root mean square (RMS) phase and amplitude error equal to 10.3° and 1.2 dB, respectively. The maximum insertion loss is equal to 8.6 dB, leading to a figure of merit of 31°/dB. As shown by simulation, by flipping PIN diodes and using negative voltage for biasing, the maximum insertion loss could be reduced to 3.6 dB (figure of merit of 75°/dB) along with a great improvement in RMS phase and amplitude errors, thus showing the potential of the proposed architecture.

다기능 투과배열 안테나 단위셀 소형화 설계를 위한 360° 반사형 축소형 아날로그 위상 천이기 설계

This study compares the designs of one-stage and two-stage reflection-type phase shifters for miniaturized S-band multi-functional transmit-array antennas. Both phase shifters have areas smaller than 0.2 λ0×0.4 λ0, which is less than half of the conventional unit cell size of 0.5λ λ0×0.5 λ0, and both phase shifters have a phase shifting range of more than 360°. The one-stage phase shifter requires a miniaturized hybrid coupler, 1/4 wavelength transmission line, and additional elements to implement a wide phase shifting range; hence, the phase shifter has a non-uniform insertion loss distribution and a peak insertion loss of 4.3 dB. The two-stage phase shifter outperformed the one-stage phase shifter; it had a relatively uniform insertion loss distribution of 2.5 dB because of its simple circuit structure.

Compact 26–30 GHz Reflection-Type Phase Shifter With 8-Bit Switched Phase Tuning Utilizing Chalcogenide Phase-Change Switches

This article reports the first implementation of a 8-bit millimeter-wave (mmWave) reflection-type phase shifter (RTPS) based on phase change material (PCM) germanium telluride (GeTe). The switched phase shifter employs a compact co-planar waveguide (CPW)-based quadrature coupler in folded tandem configuration monolithically integrated with two identical reconfigurable reflective loads optimized to achieve a large phase shift range. Reconfigurability is achieved using eight identical latching PCM switches to load or unload a desired reflective load while consuming no static dc power. Various reflective load topologies are investigated for the optimum phase shift range over the operational bandwidth. The reflective load consists of either high-frequency metal-insulator-metal (MIM) capacitors. The resonance frequency of various states is pushed beyond 40 GHz to get a resonance-free tuning zone. The fully integrated phase shifter is highly miniaturized with an overall device footprint under <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.98\times0.9$ </tex-math></inline-formula> mm, fabricated using an eight-layer in-house microfabrication process. The mmWave phase shifter demonstrates measured average insertion loss of 5.25 dB with only ±0.75 dB loss variation over 4 GHz bandwidth at 28 GHz center frequency. The proposed phase shifter exhibits a measured 280° linear phase shift in 256 discrete precision steps over 26 to 30 GHz with a figure-of-merit (FoM) of 53.3°/dB.

A 3.6 GHz Polar Reflection-Type Vector Modulator Phase Shifter With Amplitude Control Capability

This paper presents a new passive vector modulator phase shifter (VMPS) based on a polar architecture suitable for use in advanced beamforming feeding networks. The cascaded structure of a reflection-type bi-phase variable attenuator (RTBVA) and a reflection-type phase shifter (RTPS) allows great flexibility regarding phase and amplitude control, and reduces amplitude errors in phase shifting. A printed circuit operating at a central frequency of 3.6 GHz with 5-bit phase resolution was designed and implemented to validate the proposed concept. The measured results showed a 360° phase shift range, an average insertion loss of 2.4 dB at 3.6 GHz, a root-mean-square phase, and a gain error of 1.3° and 0.06 dB, respectively. This VMPS also allows an amplitude control range of ~25 dB and an operational bandwidth of 0.7 GHz (19.4%).

Design and Rectangular Waveguide Validation of 2-Bit Wideband Reconfigurable Reflective Metasurface Element in X-Band

This letter presents a new design and rectangular waveguide validation of a wideband 2-bit reconfigurable reflective metasurface (RRM) element in the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">X</i> -band. The element consists of a U-slot microstrip patch, a ground plane, and a 2-bit reflection-type phase shifter (RTPS) controlled by four p-i-n diodes. The direct circuit (DC) biases are elaborated for the 2-bit RTPS so that only two DC bias lines are required to regulate the four p-i-n diodes. The proposed RRM element has a wideband 2-bit phase resolution from 9.1 to 10.85 GHz and can be recognized with great angle stability. The rectangular waveguide experiment was conducted to prove the effectiveness of the proposed element further. The experimental results show that the 17.5% relative bandwidth is achieved under a total phase difference of 270° ± 20° with reflection losses less than 3 dB.

Tunable differential phase shifter with low in-band phase deviation error over wide phase shift range

In the brief, a tunable differential phase shifter (D-PS) which features the characteristics of low in-band phase deviation error, wide phase shift range (PSR), and compact structure is presented. The main and reference lines of the D-PS are constructed by reflection-type phase shifters (RTPSs). In the main line, the reflection load is composed of two varactors and a short-circuited stub in parallel connection. While the reflection load in the reference line is consisted of an inductor paralleled with a short-circuited stub. Design equations of the proposed D-PS is derived, and the influences of the reflection loads on the performances of the D-PS are investigated. For validation, a prototype operating at 2 GHz is designed. Measurement results show that the 10-dB impedance matching bandwidth is 20.7 %. During the tuning, a PSR of 243° is obtained and the bandwidth for phase difference error <10° is 12.1 %.

A D-Band Reflective-Type Phase Shifter Using a SiGe PIN Diode Resonant Load

This work presents a D-band phase shifter which utilizes a one-bit phase inverter (PI), followed by two cascaded reflective-type phase shifters (RTPSs). The PI uses two identical cascode amplifiers and a triaxial balun for compact form factor and to provide identical loading in both states. The RTPSs use SiGe PIN diodes for their resonant loads due to their naturally high-Q and tuning range. The phase shifter is implemented in a 90-nm SiGe BiCMOS technology platform, and achieves insertion loss < 5.5 dB with a 360° phase shift range, for frequencies up to 145 GHz. By using dual voltage control, the insertion loss variation is kept within ±0.9 dB by selecting the appropriate points. This phase shifter achieves competitive performance in terms of insertion loss, power consumption, and amplitude error while operating over a wide bandwidth.

A Planar 4-Bit Reconfigurable Antenna Array Based on the Design Philosophy of Information Metasurfaces

Inspired by the design philosophy of information metasurfaces based on the digital coding concept, a planar 4-bit reconfigurable antenna array with low profile of 0.15 λ 0 (where λ 0 is the wavelength) is presented. The array is based on a digital coding radiation element consisting of a 1-bit magnetoelectric (ME) dipole and a miniaturized reflection-type phase shifter (RTPS). The proposed 1-bit ME dipole can provide two digital states of “0” and “1” (with 0° and 180° phase responses) over a wide frequency band by individually exciting its two symmetrical feeding ports. The designed RTPS is able to realize a relative phase shift of 173°. By digitally quantizing its phase in the range of 157.5°, additional eight digital states at intervals of 22.5° are obtained. To achieve low sidelobe levels, a 1:16 power divider based on the Taylor line source method is employed to feed the array. A prototype of the proposed 4-bit antenna array has been fabricated and tested, and the experimental results are in good agreement with the simulations. Scanning beams within a ±45° range were measured with a maximum realized gain of 13.4 dBi at 12 GHz. The sidelobe and cross-polarization levels are below –14.3 and –23 dB, respectively. Furthermore, the beam pointing error is within 0.8°, and the 3-dB gain bandwidth of the broadside beam is 25%. Due to its outstanding performance, the array holds potential for significant applications in radar and wireless communication systems.

A tunable reflection‐type filtering phase shifter using SISL technology

This letter proposed a novel tunable reflection-type phase shifter (RTPS) with a filtering function using substrate-integrated suspended line (SISL) technology. First, a novel 3-dB branch-line coupler with a filtering function is designed by using broadside coupling lines. On this basis, the filtering RTPS is realized by combining with a series varactor network. The proposed SISL filtering RTPS can obtain a continuous phase shift range of 104° under 0–30 V DC bias control, which enables multifunctional integration of phase shifters. All circuits are implemented on the SISL platform, which has the advantages of double-sided wiring, self-packaging, and low loss.

A Reflection-Type Dual-Band Phase Shifter with an Independently Tunable Phase

This paper presents a design for a dual-band tunable phase shifter (PS) with independently controllable phase shifting between each operating frequency band. The proposed PS consists of a 3-dB hybrid coupler, in which the coupled and through ports terminate with the same two reflection loads. Each reflection load consists of a series of quarter-wavelength (λ/4) transmission lines, λ/4 shunt open stubs, and compensation elements at each operating frequency arm. In this design, a wide phase shifting range (PSR) is achievable at each operating frequency band (fL: lower frequency; fH: higher frequency) by compensating for the susceptance occurring at the co-operating frequency band caused by the λ/4 shunt open stub. The load of fL does not affect the load of fH and vice versa. The dual-band tunable PS was fabricated at fL = 1.88 GHz and fH = 2.44 GHz, and testing revealed that achieved a PSR of 114.1° with an in-band phase deviation (PD) of ± 8.43° at fL and a PSR of 114.0° ± 5.409° at fH over a 100 MHz bandwidth. In addition, the maximum insertion losses were smaller than 1.86 dB and 1.89 dB, while return losses were higher than 17.2 dB and 16.7 dB within each respective operating band.

Reflection-Type Phase Shifter Integrated With Tunable Power Attenuation Mechanism for Sub-6 GHz Wireless Applications

An integrated configuration of the reflection-type phase shifter (RTPS) and attenuator with simultaneous phase and amplitude control is presented for a phased-array front-end beamforming. The phase shift function of the RTPS adopts a quadrature coupler with high/low pass lumped elements and the corresponding π-type C–L–C loads. An RF tuner is subsequently incorporated into the 90° coupler to provide an energy reduction path and applied at the intermediate inductor of the coupler, thereby enabling a tunable transmission power. The merged coupler/RF-tuner realizes a matched and symmetrical structure with less impact on the load impedance variation, which can be regarded as part of the RTPS that performs RF signal degradation and maintains phase shift tuning. Furthermore, the π-type attenuator is incorporated into the RTPS to obtain an adequate power control range for the side-lobe suppression of the beamforming network. The simulated and measured results demonstrate the feasibility and suitability of the network for the proposed merged configuration applied to the phased-array system.

A Polarization and Beam Steering Reconfigurable Cavity-Backed Magneto-Electric Dipole Antenna Array Using Reflection-Type Phase Shifter

This article introduces a reconfigurable cavity-backed <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1\,\,\times4$ </tex-math></inline-formula> magneto-electric (ME) dipole antenna array with agile polarization and steerable beam features for both linear and circular polarizations (CPs). The proposed ME dipole element backed by a cavity can reduce the mutual coupling and enhance the scanning performance of the antenna array. To achieve continuous beam-scanning ability, reflection-type phase shifters are designed with varactor diodes and integrated with the feeding network. The polarization agility is determined by embedding two switchable cross strips into the ME dipole element. By manipulating the states of the two switchable cross strips through dc bias controls, three different polarization states including linear polarization (LP), left-hand CP (LHCP), and right-hand CP (RHCP) can be realized. For verification, a prototype of the antenna array was fabricated and measured. A good agreement between the simulation and the measurement is obtained, thus validating the multiple reconfigurable capability of the antenna array in polarization and radiation pattern. The measured results demonstrate that the beam can be scanned continuously in a range between ±40° for the three polarization states. Meanwhile, the measured overlapped bandwidth for the reflection coefficient ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\vert \text{S}_{11}\vert \le -10$ </tex-math></inline-formula> dB) and the 3 dB axial ratio (AR) is from 2.0 to 2.4 GHz for all states.

S-대역 레이다용 소형 다기능 투과형 메타표면 단위셀 설계 및 검증

In this study, miniaturized unit cell design and verification of multi-functional transmissive meta-surface for S-band radar are presented. The proposed unit cell comprises a receiver (Rx) antenna, a miniaturized reflection-type phase shifter, a PIN diode switch for polarization selection, and a dual-pol transmitter (Tx) antenna. The Rx/Tx antennas are stacked patch type antennas, and the reflection-type phase shifter, which has a smaller area of 36 % than a conventional hybrid coupler, controls the phase shifting from 0 to 330°. The PIN diode switch uses a −5 V reverse DC voltage bias to handle high input radio frequency (RF) power of 23 dBm. Moreover, a 1×2 unit cell array was fabricated to verify the unit cell performance. The array antenna freely converted polarized waves (horizontal/vertical) and exhibited beam steering performance in a range of approximately 50°.

A Simultaneous Beam Steering and Polarization Converting S-Band Transmitarray Antenna

In this paper, a multi-functional transmitarray antenna consisting of miniaturized unit cells for S-band radar applications is proposed. The unit cell size is 0.4λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> × 0.4λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> , and it is composed of a receiving (Rx) antenna, a miniaturized inductively-loaded reflection-type phase shifter, a PIN diode switch for polarization conversion, and a dual-polarization transmitting (Tx) antenna. The types of Rx and Tx antennas are coupled-fed stacked patch antennas. The designed reflection-type analog phase shifter has a 36 % smaller area than the conventional reflection-type hybrid coupler-based phase shifter. It has a 3-bit phase-shifting capability realized with a 0 ~ 330° analog phase shifting. The designed SPDT PIN diode switch can select the polarization of the transmitted wave and accept a high input RF power of 23 dBm. The proposed 8 × 8 transmitarray antenna with F/D of 0.33, made from its unit cell, has a gain of about 7.9 dBi and performs 90° 2D beam steering for vertical-to-horizontal and vertical-to-vertical polarization conversions at the center frequency.

Compact phase shifter using arbitrary length of two coupled transmission lines

This article presents a compact structure of two coupled transmission lines with two reactive loads for the tunable phase shifter using a printed-circuit board. The proposed circuit offers size reduction and wide phase shift range. The conventional reflection-type phase shifter approach has large total electrical length and high insertion loss. To overcome such technical issues, arbitrary-length two coupled transmission lines were introduced in this work. After optimising the length and the even-mode characteristic impedance of the coupled transmission lines, tuning the odd-mode characteristic impedance can decide the variation of two adjustable reactive loads. Based on the proposed structure, further discussion of the wideband tuning operation and measurement of the phase shift range with −20 dB return loss are addressed in this article. The fabricated circuit is measured at 700 to 2400 MHz. The even- and odd-mode characteristic impedance of two coupled transmission lines are 100-Ω and 70-Ω having about 2.16 dB maximum insertion loss, while maintaining 181-degree phase shift range and 40-degree total electrical length of transmission lines at 700 MHz, respectively, providing about 78% to 89% size reduction compared with the previous research. Our data indicates that insertion loss, multi-band operation, and miniaturisation are superior to any published data.