Wideband Phase Research Articles

Design of a 2-Bit Reconfigurable UWB Planar Antenna Array for Beam Scanning Application

Reconfigurable antennas have been widely employed for beam scanning in recent years. However, such antennas are usually limited by narrow bandwidth. To overcome this challenge, we present a linearly polarized 2-bit ultra-wideband (UWB) antenna array in C-band. The antenna array consists of 16 Vivaldi elements, 16 wideband phase shifters and a feeding network. The structural symmetry is employed to provide a couple of opposite phase states in the broad bandwidth. The measured results show that the antenna array can operate well in a broad bandwidth from 4.0 to 5.5 GHz (the relative bandwidth ~31.5%) with reflection loss lower than −10 dB. The scanning angle ranges from −45° to 45° with the sidelobe below −10dB, which agrees well with the theoretical predictions. The design features low cost, simple structure, easy fabrication and broad bandwidth.

Fully Planar 2-D Multibeam Millimeter-Wave Antenna With Via-Based Phase Shifters

For fifth-generation (5G) millimeter-wave (mmWave) beamforming, a fully planar 2 × 2 2-D multibeam antenna operating at 24–28 GHz is proposed. The proposed antenna is fed by a compact dual-layer 4 × 4 Butler matrix in substrate-integrated waveguide (SIW). In this fully planar and compact configuration, SIW coupling slot is used to facilitate the output ports of the Butler matrix on the same planar layer, and the via-based phase shifters are designed to generate wideband phase performance with compact size. The measured impedance bandwidth is 15.4%, and the measured maximum beam pointing angle is 55°. These results are in good agreement with simulation. The proposed configuration can be extended with more radiating elements for higher gain, and it is promising for beamforming scenarios, including communications.

Wideband Beam-Forming Networks Utilizing Planar Hybrid Couplers and Phase Shifters

In this article, a new approach to designing 6 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times $ </tex-math></inline-formula> 6 beamforming networks (BFNs) for producing five or six beams is presented. The configuration of the 6 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times $ </tex-math></inline-formula> 6 BFNs is designed utilizing planar wideband hybrid couplers and phase shifters. A new type of wideband hybrid coupler is built based on a slotline resonator and microstrip-to-slotline transitions. The proposed coupler design can achieve high level of isolation between the sum and difference ports. Two different formats of wideband 6 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times $ </tex-math></inline-formula> 6 BFNs are then developed, to generate five and six beams, respectively. A prototype is fabricated and tested, and the experimental results agree with the simulation ones very well, achieving a wide operating bandwidth of more than 30%. Finally, the BFN is verified by feeding a six-element array, and the realized patterns match the predicted ones very well, demonstrating the function of the BFN. The topology of an extended 12 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times12$ </tex-math></inline-formula> BFN is also given to demonstrate the possibility of creating higher-order BFNs using the presented approach.

Broadband and compact folded substrate integrated waveguide phase shifter and its application to 180° directional coupler

Abstract In this paper, a broadband, low insertion loss, and compact folded substrate integrated waveguide (FSIW) phase shifter is proposed for the first time. By loading the complementary split-ring resonators (CSRRs) on the middle metal layer of the FSIW, a closed-type slow-wave transmission line (TL) is obtained, which can provide a wideband phase shift (39%) compared with the equal-length fast-wave one. The enclosed structure of the CSRR-loaded FSIW prevents the CSRRs from radiation as suffered in the previous reported CSRR-loaded TLs, resulting in a low insertion loss. This feature greatly reduces the amplitude imbalance between the main line and the reference line of the phase shifter. In addition, no transition structure is required between the FSIWs with and without CSRRs for broadband impedance matching, which makes the phase shifter more compact and easier to integrate with other FSIW devices. To validate the performance of the proposed phase shifter and to illustrate its ease integration, a novel FSIW 180° directional coupler that consists of an FSIW 90° coupler and an FSIW 90° phase shifter is designed, fabricated, and measured. The measured results agree well with the simulated data.

Wideband Microwave Phase Noise Analyzer Based on All-Optical Microwave Signal Processing

An approach for wideband phase noise measurement of microwave signal sources is proposed based on all-optical microwave signal processing. In the proposed scheme, an optical carrier is sequentially modulated by the signal under test (SUT) in a phase modulator and a dual-polarization modulator to generate two +1st-order sidebands with orthogonal polarizations. A time delay is introduced between two sidebands by a span of low-loss optical fiber. Combined with a polarization controller and a polarizer, photonic microwave downconversion with a desired phase shift and time delay can be realized after photodetection, and the phase noise of the SUT can be calculated thereafter. Since all the microwave signal processing functions in the conventional photonic-delay-line-based phase noise measurement system are implemented in the optical domain, the proposed scheme has a large operational bandwidth and a high measurement sensitivity. In the experimental demonstration, accurate phase noise measurement of SUTs is achieved in a frequency range of 10-35 GHz, and a phase noise floor as low as −132.16 dBc/Hz at 10 kHz is obtained.

Photonic‐assisted one‐third microwave frequency divider

A microwave photonic frequency divider to produce a frequency-divided microwave signal with its frequency that is one-third the frequency of the input microwave signal is proposed and experimentally demonstrated. The key novelty of the approach is that the phase control, a condition to realise the frequency division operation, is implemented through controlling the modulator bias voltage, enabling a wideband, high resolution and fast response phase control. One-third frequency division with an ultra-high harmonic suppression of over 71.5 dB is demonstrated for the first time.

A Novel Wideband 90° Filtering Phase Shifter Using Broadside-Coupled MSLs

This brief presents a novel wideband 90° phase shifter using broadside-coupled microstrip lines (MSLs). Firstly, compared with its traditional counterpart, the proposed one can significantly increase the coupling degree as inquired in the traditional design so as to realize a much wide operating bandwidth in a simple topology. Secondly, for facilitating the design process, this brief introduces a synthesis method to efficiently design the proposed broadband phase shifter with prescribed parameters. Finally, to verify the proposed design, a prototype of the proposed phase shifter is designed, fabricated, and measured. The measured results show that the wideband phase shifter proposed in this brief can achieve 90°±3°, S <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sub> <−22 dB, and fractional bandwidth (FBW) of 80%.

Synthesis Design of Wideband Phase Shifters Using Coupled-Line Structure

In this letter, a new class of wideband phase shifters using parallel-coupled-line resonators is proposed and developed. The proposed phase shifter consists of two distinctive branches: a parallel-coupled-line filter and a reference line section. Compared with its conventional counterpart, this phase shifter has a few advantageous features such as simple geometry, small size, wide bandwidth, small phase deviation, and easy adjustment in phase shift. Then, a synthesis design method for a wideband phase shifter is described. For verification, its prototype circuit with a phase shift of 180&#x00B0; is finally designed, fabricated, and measured. Simulated and measured results are found in good agreement.

Theory and design of quasi‐lumped‐element wideband filtering phase shifters

In this article, a new general and effective design method of miniaturized quasi-lumped-element wideband filtering phase shifters for integrated RF front-end is proposed, which is promising in both industrial and academic fields. This wideband filtering phase shifter is built by exploring the multiple different kinds of lumped resonators and arranging them in an easily realizable form with stable performance on the single-layer substrate using widely accessible and low-cost PCB processing. In our design, wideband magnitude and phase shift responses with the multiple transmission zeros and small phase deviation are numerically established and obtained. A generalized synthesis method along with theoretical analysis and synthesis curves is proposed to determine its circuit parameters exactly. To verify the proposed design concept and method, two wideband phase shifter prototypes with the different topologies and specifications are implemented and tested. Comparisons of measured and simulated results show good accordance and verify theoretical predictions. These prototypes exhibit attractive features with satisfactory wide bandwidth, high frequency selectivity, small phase deviation, deep and wide stopband, miniaturized size, as well as flexible design freedom, compared to other existing works.

High gain and circularly polarized substrate integrated waveguide cavity antenna array based on metasurface

Two substrate integrated waveguide (SIW) cavity antenna arrays based on metasurface are proposed in this paper. By rotating the metasurface element, circularly polarized and high gain antennas are achieved respectively. Firstly, multi-mode resonance theory is employed to broaden the bandwidth of the slot antenna. And then, an SIW cavity composed of 4 × 4 cornercut elements is added on the top of the slot antenna to achieve the circular polarization and improve the front-to-back ratio. Thirdly, the metasurface elements are sequentially rotated and a high gain antenna with 2-dBi enhancement on average in the operation band is obtained. Based on the two antenna units, two 2×2 antenna arrays are designed. The circularly polarized and high gain antenna arrays are both fabricated to verify the correctness. Furthermore, the novel wideband phase shifter is employed in the circularly polarized antenna to obtain an operating bandwidth of 38% (4.05 GHz–5.95 GHz) and AR bandwidth of 24.9% (4.4 GHz–5.65 GHz). The bandwidth of the high gain antenna can reach 42.7% (3.95 GHz–6.1 GHz) and with the gain enhancement of 2 dBi compared with that of the circularly polarized antenna. The gain remains steady in most of operating band within a variation of 1 dBi. It is remarkable that the rotating of the metasurface element has a great influence on the antenna performance, which provides a new explication for the multi-function antenna design.

Wideband compact phase shifter based on hybrid half-mode substrate integrated waveguide and spoof surface plasmon polariton

This paper proposes a wideband compact equal-length phase shifter based on the hybrid half-mode substrate integrated waveguide (HMSIW) and spoof surface plasmon polariton (SSPP) concept for the first time. The HMSIW transmission lines (TLs) with different widths result in different propagation constants. The difference of propagation constants between two HMSIW TLs with two different widths decreases as the frequency increases. Therefore, a wideband phase shifter cannot be designed by using this technique. In this paper, a series of half-butterfly grooves are etched on the top conductor layer of the HMSIW TL to compensate the phase shift. The combination of the SSPP and HMSIW structures provides a higher degree of freedom to keep the propagation constants difference constantly. Accordingly, a wideband response can be achieved by properly tuning the structure. Here, the dispersion characteristic of the butterfly-shaped HMSIW-SSPP can be adjusted by changing the width of the HMSIW and the radius and angle of the half-butterfly grooves. Moreover, the HMSIW-SSPP structure with half-butterfly grooves reduces both longitudinal and transverse dimensions of the proposed circuit. It has more slow-wave effects than the traditional counterpart with rectangular grooves. To validate the concept, a phase shifter is designed and fabricated on a single-layer substrate at the center frequency of 5.8 GHz covering WLAN. The simulated and measured results are in good agreement. The measured results show that the phase shifter has a fractional bandwidth of 31.7% with a phase error of , an insertion of dB, and a return loss of higher than 13.8 dB. Also, the size of the proposed phase shifter is .

A Stationary Clutter Suppression Method for 3-D Micromotion Measurements Based on Wideband Radar Amplitude and Phase Information

The micromotion features of a target contain unique structural information and motion information about the target, which can be used as an important basis for target classification and recognition. To achieve high-accuracy three-dimensional micromotion measurements in the clutter environment, a stationary clutter suppression method for three-dimensional micromotion measurements based on wideband radar amplitude and phase information is proposed in this paper. This method is capable of accurately measuring the trajectory of small amplitude micromotion with the high-accuracy phase-derived angle measurement (PDAM) and phase-derived range measurement (PDRM). However, the measurement accuracy of three-dimensional micromotion deteriorates sharply when clutter exists. Thus, the main challenge that we overcome is achieving high-accuracy clutter estimation based on wideband radar measurements. The clutter suppression method is proposed by utilizing wideband radar amplitude and phase of multiple range cells jointly. Finally, simulation and experiment are presented to validate the feasibility and effectiveness of the proposed method under stationary clutter conditions.

Wideband Reflectarrays for 5G/6G: A Survey

Application demand for faster data rates is driving the need for wider operating bandwidth of future 5G/6G communication systems which in turn poses stringent requirements on the design of suitable antennas. A candidate antenna that can support 5G/6G systems are reflectarrays (RAs) due to their numerous potentials, such as high gain, beam shaping, beam scanning, reconfigurability and multi-beam characteristics. However, reflectarrays are usually limited by their narrowband characteristics. Hence, this work examines the state of the art of wideband reflectarrays. Wideband reflectarrays are reviewed and categorized according to four wideband phase tuning mechanisms. The bandwidth is reviewed and compared both from a unit cell and reflectarray system perspective with emphasis on the gain-bandwidth performance. Different wideband unit cell geometries are covered and grouped by the wideband phase tuning approach. The effect of each wideband phase tuning approach on the gain-bandwidth RA performance is then analyzed by considering the operating frequency, the reflection phase range, the substrate structure and material, the aperture size, the aperture efficiency, the focal distance, the cross-polarization performance as well as the gain and side lobe levels. Finally, the phase tuning approaches are compared against each other, and guidelines are provided for designing reflectarrays with wide gain-bandwidth.

Low-Profile Broadband Dual-Polarization Double-Layer Metasurface Antenna for 2G/3G/LTE Cellular Base Stations

A double-layer metasurface is proposed to realize the low profile of a broadband dual-polarized antenna for cellular base-station applications. The proposed metasurface is formed by the two layers of printed metallic patch unit cells on either substrate surface to miniaturize the metasurface size and enhance design flexibility by regulating the extent of electromagnetic coupling between the two layers. Despite the low profile of the antenna, a wideband operation is accomplished by operating the metasurface in the nonresonant region that facilitates wideband phase compensation and its truncation to a finite dimension with an additional transverse electric (TE) surface wave resonance. The guidelines for the design of the surface is derived from a comparison of unit cell structures and an approach is introduced to correlate their potential with surface susceptibility parameters. A detailed parametric study addresses the critical concern on the overall dimensions of the finite metasurface. A ±45°-polarized dipole antenna with an overall thickness of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.15~\lambda _{0}$ </tex-math></inline-formula> ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\lambda _{0}$ </tex-math></inline-formula> is the wavelength in free space at the center operating frequency) is designed as example. The measured results show a <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 impedance bandwidth of 46.4% over the frequency range of 1.69–2.71 GHz with average boresight gain of 9 dBi with a ground plane of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1.1\lambda _{0} \times 1.1\lambda _{0}$ </tex-math></inline-formula> , well covering 2G (1.71–1.92 GHz), 3G (1.88–2.17 GHz), and LTE (2.3–2.4 GHz and 2.5–2.69 GHz) bands.

A low profile metasurface‐based circularly polarized antenna

A wideband circularly polarized antenna with low profile based on metasurface is proposed in this article. The antenna is excited by a wideband phase shifter with four output ports. We use a wideband single-ended-to-balanced power divider; the wideband is achieved by microstrip-to-slotline transitions and a slotted T-junction. The slotlines on the ground act as multimode resonators and provide one resonator pole in operating band. We use composite right/left-handed to obtain stable phase difference at four output ports. Sequential rotation technology is used to realize wideband circularly polarized performance, the metasurface arrays is used to further improve the bandwidth. The whole structure is composed of two substrates and the two substrates are connected with metal pillars. The wideband circularly polarized antenna is designed, fabricated, and measured. The measured results show that the 37.4% impedance matching is obtained, ranging from 5 to 7.3 GHz. And the 3 dB axial ratio fractional bandwidth is 31.8%, ranging from 5.25 to 7.15 GHz. The maximum measured gain is 10.24 dBi, showing good agreement with the simulated results.

28–38-GHz 6-bit Compact Passive Phase Shifter in 130-nm CMOS

In this letter, a highly compact, bidirectional, wideband 6-bit resolution passive phase shifter (PS) is presented in low-cost 130-nm CMOS technology. A compact Lange differential hybrid is designed in this letter to provide quadrature signals from the input. The compact Lange hybrid is followed by a switching matrix that generates weighted sums of the quadrature signals to cover 360° and additional controlled loss using single pole single throw (SPST) switches. The matrix consists of 12 transistors, each of which is controlled by a three-level gate voltage (0, 0.6, and 1.2 V) providing higher resolution in phase shifts. The chip achieves the state-of-the-art performance with 10-dB insertion loss across 28–38 GHz. The chip also achieves an rms gain error of 0.6 dB and an rms phase error of 3° in the bandwidth, consuming no dc power and only 0.15 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> including baluns.

Optical transmission experiment on FM conversion method with wideband phase modulation

Optical transmission experiment on FM conversion method with wideband phase modulation

Photonic microwave synthesizer based on optically referenced sub-sampling phase-locked optoelectronic oscillator

Wideband and low phase noise microwave synthesizers are of critical significance for various applications. Phase-locked loop (PLL) based microwave synthesizers are widely used. Normally, the phase noise of the PLL based microwave synthesizer is limited by the phase noise of the reference, phase detector, frequency divider and voltage-controlled oscillator (VCO). It is challenging to achieve a pure electronic microwave synthesizer with wide frequency coverage and low phase noise, simultaneously. Here, we propose a photonic microwave synthesizer which incorporates an ultra-low phase noise fiber mode-locked laser (MLL) based reference and a wideband frequency tunable optoelectronic oscillator (OEO) based VCO in a hybrid optoelectronic sub-sampling PLL. The frequency of the OEO can be locked to the harmonics of the repetition-rate of the fiber MLL, which combines the distinct advantages of the low phase noise of MLL and the wideband frequency tuning of OEO. A sub-sampling phase detector formed by a balanced optical microwave phase detector (BOMPD) eliminates the use of RF frequency divider and maintains low residual phase noise. We attain an X- and Ku-band photonic microwave synthesizer with over an octave frequency coverage from 8 GHz to 18 GHz, frequency synthesis step of 60.74 MHz and phase noise of -80 dBc/Hz at 100 Hz offset and -100 dBc/Hz at 1 kHz offset for 10 GHz output. The characteristics of the optoelectronic sub-sampling phase detector, the phase-locking dynamics of the hybrid optoelectronic PLL, and the phase noise of the synthesized RF signals are both theoretically and experimentally investigated. The experimental results agree well with the theoretical models. Our approach is promising to achieve wideband and low phase noise microwave synthesis.

Low-Cost, Low-Profile Wide-Band Radar Cross Section Reduction Using Dual-Concentric Phase Gradient Modulated Surface

Design criteria of low-cost, dual-concentric metasurface possessing wideband phase gradient (PG) are introduced. The radar cross-section reduction (RCSR) is explained by anomalous reflection that characterizes the superficial planar. The geometry consists of two single band RCSR modulated surfaces (MSs) that are triggered in each other. Each MS is built-up of square patch (SP) unit cells configured as a modulation structure to realize PG that causes anomalous reflection and monostatic RCSR behavior. Applying sinusoidal modulation to the sequence of the SP unit cells leads to the formation of PG along the surface and hence the intensity of the reflected wave is reduced for the broadside direction (θr=0∘). The proposed structure fabricated on a 0.8 mm thin FR-4 substrate extends over 249 × 249 mm2. It achieves a wide RCSR bandwidth from 20.9 GHz to 45.7 GHz (i.e., relative bandwidth of 75%) as designed in Dassault Systèmes (CST) Microwave Studio as a full-wave simulator and confirmed by the measurement results.

Design of wideband phase shifter with edge-coupled semi-elliptical lines

The analysis and design of a wideband phase shifter using semi-elliptical edge-coupled structure is presented. An elliptical defected ground plane at the bottom layer is also incorporated to increase the coupling coefficient and operating bandwidth. Even and odd mode analysis has been performed and sets of design graphs are formulated to facilitate the design of the phase shifter on substrate with dielectric constant of 2.2 and 3.38. The differential phase shift is controlled by the coupling factor while the operating frequency is determined by the physical dimensions. Both simulation and measurement results show that the proposed design exhibits wideband characteristic with a phase deviation within ±4°, an insertion loss less than 1 ​dB and a return loss better than 10 ​dB. The achievable bandwidth is more than 2.4 : 1 for coupling factor of 5 ​dB which gives a differential phase shift of 80°.