Wide Phase Shift Range Research Articles

Two-frame random phase shifting interferometry based on constrained Kalman filter without pre-filtering

This paper discusses a phase estimation algorithm in two-frame phase-shifting interferometry using a constrained Kalman filter without the need of pre-filtering operation for the background intensity removal. A state-space model is developed and state estimation is performed based on the extended Kalman filter. The Kalman smoother algorithm is utilized to improve the accuracy of state estimation. A comparative study is presented between the proposed and four state-of-art phase estimation methods. Both simulation and experimental results show good accuracy and noise robustness of the proposed method over a wide range of phase shifts.

A Singly Curved Conformal Phased Array with Integrated Particles-Based CRLH Phase Shifters

In this paper, a four unit cell micron-sized magnetic particles embedded composite right/left-handed (CRLH) transmission line metamaterial phase shifter is proposed. The variable phases are achieved by activating the micron-sized magnetic particles along the length of stub transmission lines of the CRLH transmission line structure. This causes to effectively change the inductance of stub transmission lines, which changes the phase of the RF signal. These structures can be activated in a symmetric or asymmetrical manner to obtain wide range of phase shifts. A prototype of cascaded four unit cell CRLH transmission line phase shifter with embedded silver-coated ferrites (magnetic particles) is designed, fabricated and tested for phase shifters applications. The measured phase response of the proposed phase shifter is in close agreement with the simulated phase response. Next, for the performance analysis of proposed phase shifter, a 1 × 4 conformal curved-shaped phased array operating at 5.8 GHz is fed with the four unit cell cascaded phase shifter in CST full-wave simulator. The conformal phased array with proposed integrated phase shifters was simulated for broadside pattern correction and main beam scanning at 20 degree on curved-shaped surface with different bend angles. The radiation pattern results obtained with the proposed integrated phase shifters are in close agreement with those obtained with direct excitation of the array.

A Balanced Substrate Integrated Waveguide Phase Shifter with Wideband Common-Mode Suppression

In this paper, a slotted substrate integrated waveguide (SIW) is used to create a balanced phase shifter with wideband common-mode (CM) suppression. Differential-mode (DM) impedance matching and CM suppression are achieved by utilizing the fact that TE20 mode and TE10 (TE30) mode can only transmit DM signals and CM signals, respectively, and by increasing the bandwidth for CM suppression via slots. Furthermore, a wideband phase shift with low phase deviation can be obtained due to the phase slop counteract between the slot and the delay line. Compared with the state-of-the-art, the proposed one has the advantages of wideband CM suppression, wide phase shift range, and a simple and easy-to-make structure. Five prototypes covering the frequency of 3.5 GHz are designed with the relative operating bandwidth for 45° ± 2° (90° ± 4.5°, 135° ± 6°, and 180° ± 8°) phase shifter of 20% (20%, 20%, and 20%), with the minimum insertion loss of 0.41 dB (0.5 dB, 0.58 dB, and 0.59 dB), with the minimum return loss greater than 15 dB, and with the relative bandwidth for 15-dB CM suppression of 59% (59%, 58%, and 57%).

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 %.

Low-Loss Mechanically Tunable Resonator and Phase Shifters in Groove Gap Waveguide Technology

This research is focused on the design and realization of high-performance high-power variable phase shifters in groove gap waveguide technology. Specifically, it is shown that the unique characteristic of groove gap waveguides, which is its proper operation without the need for electrical connection between the top and bottom sections of the waveguide, can be used to design mechanically tunable devices. Using the proposed method, a mechanically tunable cavity resonator and phase shifters with a wide range of achievable phase shifts are presented. To validate the concept, a phase shifter with 540 degrees relative phase shift at 15 GHz is designed, fabricated, and measured. Moreover, a multi-layer version of the proposed phase shifter with stationary feed ports and improved performance is presented.

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.

Simple ladder‐like single‐layer balanced wideband phase shifter with wide phase shift range and appropriate common‐mode suppression

In this study, a single-layer balanced wideband phase shifter with a wide phase shift range of 45°–315° and acceptable common-mode (CM) suppression is proposed. The main branch has a simple ladder-like structure and the reference branch utilises a coupling structure. The main branch electrical length is constant for any desired differential-mode (DM) phase shift. Assuming a specific return loss (e.g. 16, 20, and 25 dB), the phase shifter is carefully analysed and a design procedure is given leading to an ultra-low phase error design. Then by making a trade-off between the CM and DM bandwidths at the cost of higher phase error, more design solutions for the phase shifter are given. To validate both the proposed structure as well as its design procedure, a balanced wideband phase shifter with the DM phase shift of 180°±4.2° (1.851–4.017 GHz) and the CM suppression of better than 15 dB (1.81–4 GHz) is fabricated, resulting in 73.82 and 75.25% fractional bandwidth, respectively. The fabricated balanced phase shifter has a return loss of and insertion loss of . The synthesised, simulated, and measured results are in good agreement with each other.

Differential phase shifters based on Schiffman type‐C and type‐F networks with wide phase shift range

This study proposes a class of differential phase shifters based on the Schiffman type-C and type-F networks with wide phase shift range. After the phase and bandwidth properties of these two distinct networks are numerically analyzed, two unique advantages of wide phase shift range and wide phase shift bandwidth are revealed. Next, the optimal design parameters for different phase shift values up to 405° are presented to allow for a quick design process. To verify the proposed approach, a 180° differential phase shifter is designed, fabricated and measured. Good performance is achieved with an impedance ratio of 1.959 and 3.7° phase deviation over a phase shift bandwidth of 61%.

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).

A Compact Wideband Phase Shifter Using Slotted Substrate Integrated Waveguide

A compact phase shifter using substrate integrated waveguide (SIW) with two slots is proposed in this letter. The wideband phase shift is mainly caused by the opposite phase shift slopes produced by the slots and the microstrip delay lines over a wide frequency range. Furthermore, the wide phase shift range (−90° to 90°) can be achieved and be with the same reference line. Compared with the state of the arts, the proposed one gives consideration of the wide bandwidth, wide phase shift range, simple and compact size, and easy-to-make structure, while the SIW counterparts just consider part of the above features. Five prototypes covering the frequency of 26 GHz are designed with the operating bandwidth for 90° ± 5° (−45° ± 2.5°, 45° ± 2.5°, and 90° ± 5°) phase shifter of 26.6% (29.2%, 35.8%, and 39.3%) and the size of $2.29\lambda _{g}^{2}$ ( $2.42\lambda _{g}^{2}$ , $2.71\lambda _{g}^{2}$ , and $2.86\lambda _{g}^{2}$ ; $\lambda _{g}$ is the guided wavelength at the center frequency $f_{0}$ ).

Application of Wideband Differential Phase Shifters With Wide Phase Range in Chipless RFID Readers

Eliminating the strong self-interference signal in chipless radio frequency identification (RFID) readers is key for enabling a reliable and long range reading in chipless RFID readers. The suggested method is to add a compensation signal to cancel the leakage signal vectorially before the first stage of the receiver front-end. An ultra-wideband (UWB) polyphase power divider (PPPD) generates the vector compensation signal of any arbitrary amplitude and phase. Unfortunately, the reported PPPD cannot meet the requirements for the realization of a UWB compensation unit (CU). A microstrip wideband differential phase shifter capable of producing a wide range of phase shifts is presented in this paper. The delay lines, including transmission line (TL) segments loaded with shorted stubs (SSs), generate prescribed phase shift values with respect to the universal reference line. It is shown that an arbitrary phase shift (up to 360°) with an in-band return loss (RL) better than 15 dB within an octave bandwidth is obtainable. Its full-range phase shift capability alongside the universal reference line and simple structure ensure its suitability for polyphase applications. To verify the proposed structure, a set of C-band phase shifters ranging from 60° to 300° is designed and fabricated, and a phase deviation from ±1° to ±9° is obtained. Finally, based on the proposed differential phase shifter, a four-phase power divider is implemented and utilized in the CU of a chipless RFID reader. Excessive isolation of better than 35 dB over 4–8-GHz frequency band is attained.

Balanced Wideband Phase Shifters With Wide Phase Shift Range and Good Common-Mode Suppression

This paper proposes a class of balanced wideband phase shifters with wide phase shift range and good common-mode (CM) suppression. Both the balanced filtering units in the reference and main branches consist of horizontal half-wavelength branches and vertical quarter-wavelength loaded stubs but with dissimilar sizes. The differential-mode (DM) section of these two units can achieve ( $2N + 1$ )th-order Chebyshev amplitude response while with discrepant phase characteristics, which can be utilized in the design of balanced phase shifters with large phase shift. As another interesting feature, the proposed balanced filtering unit functions as the conventional branch-line bandstop response in CM, and its frequency selectivity can be further enhanced by using the so-called signal-interference method. The proposed balanced wideband phase shifters have the advantages of wide phase shift range, low phase deviation, high level and wide range for CM rejection in both two branches. The 30°, 60°, 90°, 120°, 150°, and 180° balanced phase shifters are then studied and designed. As the typical examples, 30°, 90°, and 180° phase shifters are designed, fabricated, and measured. The 30° and 90° phase shifters have a fifth-order Chebyshev response, while the 180° phase shifter is of fifth-order and third-order Chebyshev responses in the reference and main branches, respectively. The measured results show that the phase shift values are 30.14° ± 2.2°, 90.75° ± 4.05°, and 180.1° ± 5.5°, the phase shift bandwidths are 73%, 68.5%, and 66.8%, and the CM rejections are −23.3, −22, and −14.6 dB, respectively.

A Wideband Tunable Reflection-Type Phase Shifter With Wide Relative Phase Shift

Wide bandwidth, wide tunable phase range, and a compact circuit size are always desired for the tunable phase shifter utilized in the modern wireless communication system. However, the existing reflection-type phase shifter configurations cannot satisfy all these requirements simultaneously. To resolve these problems, the reflection load consisting of two tunable capacitors and a quarter wavelength transmission line is utilized on a vertically installed planar structure to implement a new reflection-type phase shifter. For demonstration, a reflection-type phase shifter is designed, fabricated, and measured. A wide bandwidth of 66.7% defined by 10-dB return loss had been achieved. Over the same band, a wide phase shift range up to 407° can be observed. Meanwhile, the fabricated circuit occupies a compact circuit size of ${0.26\lambda _{g} *0.37\lambda _{g}}$ .

Zero difference algorithm for phase shift extraction in blind phase-shifting holography

A simple noniterative algorithm for retrieval of the unknown phase shifts in phase-shifting holography is proposed. In this algorithm, the phase shift value between two phase-shifting holograms can be calculated through a simple analytical formula that is derived according to the fact that there exist some points whose intensity difference between two phase-shifting holograms is equal to zero. Both the simulated and experimental results demonstrated the feasibility of this so-called zero difference algorithm over a wide range of phase shifts.

소형화된 5.3 GHz 대역 360° 아날로그 위상천이기 설계

본 논문에서는 주파수 5.3 GHz에서 소형화된 branch line 커플러와 <TEX>$360^{\circ}$</TEX> 이상의 위상천이를 보일 수 있는 가변 리액턴스 부하를 결합하여 소형화된 위상천이기의 설계를 보였다. 위상천이기의 소형화를 위하여, branch line 커플러의 새로운 구조를 제안하였다. 새로운 branch line 커플러는 전송선의 T 및 <TEX>${\pi}$</TEX>형 등가회로 변환 방법을 이용하여 소형화하였다. 소형화된 branch line 커플러는 일반적인 구조에 비해 50 % 이상 소형의 크기를 가진다. 넓은 위상천이량을 갖기 위하여 전송선에 버렉터 다이오드 두 개를 입력과 출력에 연결한 부하 구조를 채택하였다. 특히, 조정 전압에 대한 위상천이량이 완만하도록 임피던스 변환기 역할을 하는 전송선을 설계된 부하 구조에 추가하여 구조를 보완하였다. 추가된 임피던스 변환기에 사용된 전송선 및 선정된 부하 구조의 전송선은 소형화에 장애가 되기 때문에 이를 집중 소자로 등가하여 소형화하였다. 제작된 위상천이기는 <TEX>$15{\times}15mm^2$</TEX>의 소형의 크기를 가지며, 조정 전압 0~10 V 범위의 경우, 중심 주파수 5.3 GHz에서 삽입 손실은 약 -4~-6 dB, 반사 손실은 -20 dB 이하, 약 <TEX>$480^{\circ}$</TEX>의 넓은 위상천이를 보였다. In this paper, a design and fabrication of miniaturized 5.3 GHz reflection type <TEX>$360^{\circ}$</TEX> analog phase shifter with branch line coupler and <TEX>$360^{\circ}$</TEX> variable reactance load. In order to miniaturize phase shifter, novel branch line coupler is proposed. The novel branch line coupler is miniaturized using transformation of transmission line to T and <TEX>${\pi}$</TEX> type equivalent circuit. The miniaturized branch line coupler has small size of above 50 % compared with conventional branch line coupler. For wide phase shift range, <TEX>$360^{\circ}$</TEX> variable reactance load structure is adopted. Especially, the structure was improved for linear phase shift by adding transmission line which acts as an impedance transformer. The improved structure was miniaturized using the equivalent lumped-element of transmission line. The fabricated phase shifter with <TEX>$15{\times}15mm^2$</TEX> shows wide phase shift of above <TEX>$480^{\circ}$</TEX>, the insertion loss of -4~-6 dB and the reflection loss of below -20 dB at 5.3 GHz under 0~10 V control voltage range.

Terahertz Antenna Phase Shifters Using Integrally-Gated Graphene Transmission-Lines

We propose the concept and design of terahertz (THz) phase shifters for phased antenna arrays based on integrally-gated graphene parallel-plate waveguides (GPPWGs). We show that an active transmission-line may be realized by combining GPPWGs with double-gate electrodes, in which the applied gate voltage can control the guiding properties of the gated sections. This may enable the realization of THz electronic switches and tunable loaded-lines for sub mm-wave antenna systems. Based on these active components, we theoretically and numerically demonstrate several digital and analog phase shifter designs for THz frequencies, with a wide range of phase shifts and small return loss, insertion loss and phase error. The proposed graphene-based phase shifters show significant advantages over other available technology in this frequency range, as they combine the low-loss and compact-size features of GPPWGs with electrically-programmable phase tuning. We envision that these electronic phase shifters may pave the way to viable phased-arrays and beamforming networks for THz communications systems, as well as for high-speed, low-RC-delay, inter/intra-chip communications.

Closed-Form Approximations to the Threshold Quantities of Distributed-Feedback Lasers With Varying Phase Shifts and Positions

We derive analytical approximations to the threshold gain, detuning, and power distribution ratios of distributed-feedback lasers with a variable phase shift at a variable longitudinal position. These closed-form approximations exhibit the direct influence of the grating parameters, and are in excellent agreement with the exact solution of the coupled mode equations for a wide range of phase shifts, positions, grating strengths and lengths. It is shown that the product of grating strength and phase shift offset distance from the grating center has a dominant influence on most threshold parameters. The threshold gain and output power splitting ratio grow exponentially with this product, whereas the intracavity peak power and the Q-factor of the cavity decay exponentially with it. It is also shown that a nonvanishing sine of the phase shift leads to a linear change of the detuning, a quadratic increase of the threshold gain, and a quadratic decrease of the output power splitting ratio, intracavity peak power, and Q-factor. Our results are independent of the source of the gain, such as semiconductor, rare-earth, and Raman fiber lasers, provided that the gain is approximately constant along the grating length and that reflections from facets can be neglected. As an example, we simulate a Raman DFB laser and demonstrate that our closed-form approximations are in perfect agreement with steady state results from involved time-domain simulations.

Wavefront reconstruction by two-step generalized phase-shifting interferometry

A wavefront reconstruction method by two-step generalized phase-shifting interferometry (GPSI) with blind phase shift extraction algorithm is verified by both the computer simulations and optical experiments. This method can retrieve complex object wave field by using two interferograms, the recorded object and reference wave intensities, and an unknown phase shift without additional processing. The simulations with irregular wavefronts have shown the effectiveness and high accuracy of this method for blind phase-shift extraction and wavefront reconstruction over a wide range of phase-shifts, while the optical experiments for both the direct and indirect objects have yielded satisfactory results with a higher resolution of reconstructed image than those reported recently.

Simple direct extraction of unknown phase shift and wavefront reconstruction in generalized phase-shifting interferometry: algorithm and experiments

An algorithm to extract the arbitrary unknown phase shift and then reconstruct the complex object wave in generalized phase-shifting interferometry (GPSI) without the iteration process and measurement of object wave intensity is proposed. This method can be used for GPSI of any frame number >or=2. Both computer simulations with smooth and diffusing object surfaces and optical experiments have verified the effectiveness of this method over a wide range of phase shifts with very satisfactory results.

Relation of external surface to internal tumor motion studied with cine CT

The accuracy of delivering gated-radiation therapy to lung tumors using an external respiratory surrogate relies on not only interfractional and intrafractional reproducibility, but also a strong correlation between external motion and internal tumor motion. The purpose of this work was to use the cine images acquired by four-dimensional computed tomography acquisition protocol to study the relation between external surface motion and internal tumor motion. The respiratory phase information of tumor motion and chest wall motion was measured on the cine images using a proposed region-of-interest (ROI) method and compared to measurement of an external respiratory monitoring device. On eight lung patient data sets, the phase shifts were measured between (1) the signal of a real-time positioning-management (RPM) respiratory monitoring device placed in the abdominal region and four surface locations on the chest wall, (2) the RPM signal in the abdominal region and tumor motions, and (3) chest wall surface motions and tumor motions. Respiratory waveforms measured at different surface locations during the same respiratory cycle often varied and had significant phase shifts. Seven of the 8 patients showed the abdominal motion leading chest wall motion. The best correlation (smallest phase shift) was found between the abdominal motion and the superior-inferior (S-I) tumor motion. A wide range of phase shifts was observed between external surface motion and tumor anterior-posterior (A-P)/lateral motion. The result supported the placement of the RPM block in the abdominal region and suggested that during a gated therapy utilizing the RPM system, it is necessary to place the RPM block at the same location as it is during treatment simulation in order to reduce potential errors introduced by the position of the RPM block. Correlations between external motions and lateral/A-P tumor motions were inconclusive due to a combination of patient selection and the limitation of the ROI method.