MEMS variable‐capacitor phase shifters part I: Loaded‐line phase shifter

This article describes the design and characterization of a continuously variable loaded‐line phase shifter using micro‐electro‐mechanical system (MEMS) variable capacitors as phase shifting components. The design and characterization of micro‐electro‐mechanical system (MEMS) variable capacitors for operation at 26.5 GHz is described. A lumped‐element model is obtained from measurements and physical consideration. Experimental results show a capacitance‐tuning ratio of 3.7:1. The capacitor's characterization results are used for designing the phase shifter. A phase shift of 40.5° at 26.5 GHz for a loaded‐line type has been measured. There is good agreement between simulated and measured results. A companion article (Part II) describes the application of these variable capacitors to the design of reflection‐type phase shifters. © 2003 Wiley Periodicals, Inc. Int J RF and Microwave CAE 13: 321–337, 2003.     

Differential phase shifters using corrugated,ridge, and fin loaded waveguides

One means of converting the port conditions of a magic‐tee into those of a 90° hybrid is to introduce external sections of waveguide at the symmetrical H‐plane output ports having the necessary 90° phase difference. The purpose of this article is to describe a number of realizations of such differential phase shifters (DPS), including an exact synthesis procedure not requiring computer optimization. A typical design consists of a capacitively loaded waveguide for one section and an essentially inductive waveguide for the other. The latter is simply a uniform waveguide of reduced width when compared with that of the capacitive section. An example capacitive ridge DPS exhibits a maximum phase error of ±2° over a 20% bandwidth in WR75 waveguide with a return loss of better than 40 dB and an insertion loss <0.06 dB. © 2009 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2009.     

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%.     

Reconfigurable H‐plane waveguide phase shifters prototyping with additive manufacturing at K‐band

This work presents the design and manufacturing of a K‐band reconfigurable phase shifter completely implemented in waveguide technology for reduced insertion loss, good matching, and large phase shifting range. The device is based on the combination of a short slot coupler and two tunable reactive loads implemented as a section of short‐circuited waveguide where an adjustable metallic post is inserted. Three prototypes of this design have been manufactured using different techniques (conventional computer numerical control machining, a low‐cost fused filament fabrication technique and direct metal laser sintering) in order to assess its performance for different applications. The prototypes have been characterized experimentally and the achieved results are evaluated and compared. The proposed phase shifter, since it is fully developed in waveguide technology, eliminates the need of adding transitions to planar structures in order to integrate lumped components like pin diodes or varactors. Therefore, this device has a great potential in high‐power beam steering phased arrays.     

A new design of multi-bit RF MEMS distributed phase shifters for phase error reduction

In this paper, the major source of phase error for multi-bit MEMS distributed phase shifters, the mismatch between adjacent bits, is investigated. A quantitative account of the phase deviation with the effect of mismatch considered is presented by the simulated results as well as theoretically calculated results. A novel multi-bit distributed MEMS phase shifter aimed to eliminate this error source is proposed. The basic concept for the structure is that, by controlling the phase shifter from the unit cell level, performance deterioration resulted from multiple reflection of the signal in the device in the phase state switching process is avoided. To verify the feasibility of the proposed structure, two X-band 5-bit distributed phase shifters are designed and simulated. Compared with the traditional structure, the average phase errors in all phase states of the two are improved by 28.22 and 36.52 % at 10 GHz. The average RMS phase errors in the bandwidth of 1–12-GHz of 56 frequency points are 1.23° and 1.85°. The improvements of the return loss and insertion loss are also exhibited. Furthermore, the aperiodic distributed phase shifter using different unit cells is introduced to demonstrate that the proposed structure can also be used to decrease the number of MEMS switches of multi-bit MEMS distributed phase shifters.     

Ka‐band phased patch array antenna integrated with a PET‐controlled phase shifter

In this article, a 4 × 4 linear‐phased patch array antenna, consisting of four 1 × 4 patch subarrays and a true time‐delay multiline phase shifter, is proposed on a thin film liquid crystal polymer substrate at Ka‐band. The patch antenna is designed with a gain of 6 dBi at 35 GHz and a bandwidth of 23% centered at 35 GHz. To enhance the gain and symmetrize the beam patterns of the 4 × 4 array, a 1 × 4 patch subarray in the E‐plane was designed and characterized. The subarray produces an enhanced gain of 11 dBi and a wide beamwidth of ±38° in the H‐plane for beam steering. The proposed phase shifter comprises a 1 × 4 microstrip line power splitter and a piezoelectric transducer‐controlled phase perturber. A large phase variation of up to 370° and a low insertion loss of less than 2 dB were demonstrated for the phase shifter at Ka‐band. The integrated phased array attains a gain of 15.6 dBi, and a continuous true‐time delay beam steering of up to 33 ± 1° from 31 to 39 GHz. © 2015 Wiley Periodicals, Inc. Int J RF and Microwave CAE 26:199–208, 2016.     

A quantized water cycle optimization algorithm for antenna array synthesis by using digital phase shifters

In this article, a quantized water cycle algorithm (QWCA) is used for the antenna array pattern synthesis with low side‐lobe levels (SLLs) and nulls at desired directions by using four‐bit digital phase shifters. In addition to the standard features as a metaheuristic algorithm, QWCA has an internal quantization mechanism and a precalculated array factor method. The latter provides an accelerated procedure to QWCA under favour of the digitized values that can be stored in a three‐dimensional array. This acceleration is based on the reality that the accessing data in the memory need less time than the usage of the mathematical functions throughout the optimization process. The internal quantization mechanism of QWCA is utilized to achieve digital values matching to the discrete values of the phase shifter instead of the simple rounding up/down routines after optimization. The numerical results showed that QWCA can obtain very good SLLs and null depth levels (NDLs) on the synthesized pattern. Moreover, the results are achieved in remarkably short optimization times. SLL and NDL values obtained by QWCA are also compared with the available literature values. The comparisons reveal that QWCA is able to produce better results than the other compared alternatives. © 2014 Wiley Periodicals, Inc. Int J RF and Microwave CAE 25:21–29, 2015.     

A new active structure of high frequency wide band differential phase shifters

The design and performance of a wide band active GaAs IC 180° differential phase shifter are presented. A two-stage GaAs IC was developed containing a microwave differential amplifier and a matched common-gate input. The active phase shifter achieved a 10° phase unbalance and an isolation at the output ports of better than 10 dB in the 1-10-GHz band. A large percentage of the GaAs chip contains active devices thereby providing a very large operating bandwidth and a reduced surface area. This active phase shifter presents an interesting alternative to the passive rat-race or an equivalent coupler for radio mobile communications. © 1996 John Wiley & Sons, Inc.     

A SiGe BiCMOS phase shifter based on quarter‐wave coupled resonators

This work presents the first example of monolithically integrated phase shifter based on a pass‐band filter architecture. The proposed configuration was realized mapping a classical quarter‐wave coupled filter circuit into its lumped element equivalent. Phase control is achieved by controlling the pass‐band through tunable tanks employing varactor diodes. A demonstrator was prototyped in the 24 GHz ISM band using a 0.25μm SiGe BiCMOS technology. Experimental results show 180° of phase range and maximum transmission losses of 8 dB. The main feature of this configuration is that it allows controlling the transmission losses by design and that its size is extremely compact.     

The low-cost polarization reconfigurable phased array based on high-precision full 360° phase shifter

In this article, to adapt the various polarization of user terminal, a 1 × 4 C-band high-integrated polarization reconfiguration phased array based on phase shifter matrix is presented. The phased array combined with polarization reconfiguration antenna elements exhibits the desired beamforming patterns and achieves beam polarization reconfiguration simultaneously. Based on the technique of the shunted microstrip open-stub and equalizing resistor, a high-precision reflection-type phase shifter with full 360° continuous phase tuning range is designed for this phased array in this article. The prototype of the polarization reconfiguration phased array is designed and fabricated. Measured results show that proposed phased array works at 5.8 GHz and achieves 21.4% (1.2 GHz) impedance bandwidth and 14.3% (800 MHz) 3 dB axial ratio bandwidth. The beam coverage range at 5.8 GHz is more than 64° with 0.2° beam steering resolution.     

Design and consideration of wafer level micropackaging for distributed RF MEMS phase shifters

A novel packaging structure which is performed using wafer level micropackaging on the thin silicon substrate as the distributed RF MEMS phase shifters wafer with vertical feedthrough is presented. The influences of proposed structure on RF performances of distributed RF MEMS phase shifters are investigated using microwave studio (CST). Simulation results show that the insertion loss (S₂₁) and return loss (S₁₁) of packaged MEMS phase shifters are −0.4–1.84 dB and under −10 dB at 1–50 GHz, respectively. Especially, the phase shifts have well linear relation at the range 1–48 GHz. At the same time, this indicated that the proposed pacakaging structure for the RF MEMS phase shifter can provide the maximum amount of linear phase shift with the minimum amount of insertion loss and return loss of less than −10 dB.     

Synthesis of frequency‐independent phase shifters using negative group delay active circuit

This article describes a synthesis method dedicated to the design of frequency‐independent phase shifters (PSs). This innovative PS structure consists in a transmission line cascaded with a negative group delay (NGD) active circuit so that the absolute constant group delays generated by both of them are identical but of opposite signs. So, in principle, it exhibits a constant overall phase and a group delay close to zero. Broadband linear positive phase slopes are obtained through use of an NGD active circuit whose characteristics are recalled prior to the extraction of the PS synthesis relations. The design and simulations of a PS of compact size are reported. The experimental results confirm the expected frequency‐independent transmission‐phase value of 145° ± 10° with an insertion gain of 2 ± 2 dB over a 160% relative frequency band. At last, future prospects allowed by the specific properties of this PS are presented. © 2010 Wiley Periodicals, Inc. Int J RF and Microwave CAE , 2010.     

A novel approach to minimize RMS errors in multifunctional chips

In this contribution, a novel approach, based on single cells permutations, is presented for the minimization of RMS errors in digitally controlled subsystems. The method is described and demonstrated for phase‐shifting functionalities, but it can be easily applied to different subsystems. By using the proposed approach, the designer is able to choose the best cell configuration, fulfilling arbitrary specification goals. An X‐band GaAs multifunctional chip (MFC) for T/R Module applications, composed by a six‐bit phase shifter, six‐bit attenuator, T/R switch, and on‐board serial‐to‐parallel converter has been designed, realized, tested, and presented here as a test vehicle of the methodology. Measured results include a 4.5° maximum RMS phase error, 1.2 dB maximum RMS spurious amplitude error, and better than 13 dB input and output return losses for all phase and amplitude settings over the whole 9.0–10.2 GHz operating bandwidth. © 2012 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2012.     

Mode‐matching analysis of H‐plane ferrite‐loaded rectangular waveguide discontinuities

The full set of eigenmodes existing in a ferrite‐slab‐loaded rectangular waveguide is first obtained and then used to compute the scattering matrix of a junction between an air‐filled rectangular waveguide and an H‐plane ferrite‐slab‐loaded rectangular waveguide by using the mode‐matching method. Numerical results for the scattering parameters of the H‐plane waveguide discontinuity are compared to experimental data and those obtained by Ansoft's HFSS. Good agreement is observed. To demonstrate the usefulness of this structure, a computer‐optimized 90° nonreciprocal phase shifter is designed using an H‐plane ferrite‐slab‐loaded waveguide. With only one‐step impedance matching sections at both ends of the ferrite slab, a compact design is achieved to have 2° phase error and less than ?30 dB return loss over about 5% bandwidth. © 2003 Wiley Periodicals, Inc. Int J RF and Microwave CAE 13: 259–268, 2003.     

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.     

Microstrip stepped‐impedance ring all‐pass filter and wideband 90° phase shifter

A new all‐pass filter (APF) is proposed. The APF is based on a symmetrical ring, consisting of four sections of transmission line, which are identical in electrical length, different in characteristic impedance. Two input/output ports are connected orthogonally to the ring. The APF is analyzed by using the odd‐even model, and the all‐pass condition is then theoretically obtained. Meeting the condition, the circuit is all‐pass in frequency, but nonlinear in transmission phase. The nonlinear transmission phase with frequency may be adjusted by changing the lines' impedances, while remaining the all‐pass property. Then the APF is used to design a wideband 90° differential phase shifter with adjustable bandwidth. Samples are designed, fabricated and measured. Good agreements are achieved among the theoretic, numerical and experimental results. © 2013 Wiley Periodicals, Inc. Int J RF and Microwave CAE 24:191–195, 2014.     

Reconfigurable multibeam feed network for 38 GHz application

A feed network based on substrate integrated waveguide for 38 GHz application is proposed in this article. The network consists of a 90° hybrid, a 180° hybrid, a power divider, and a switchable phase shifter. There are two input ports in the reconfigurable multibeam feed network (RMBFN) and a set of symmetrical radiation pattern will be excited by the two input ports. In addition, the other symmetrical patterns will be obtained by adjusting the different states of the switchable phase shifter. The simulated results show that the S₁₁ and S₂₂ are found to be better than ?13 dB over 37‐40 GHz. Meanwhile, the amplitude of the three output ports is about ?6.6 ± 1 dB, and the phase difference is ±60 ± 10° or ±120 ± 10°. When the proposed RMBFN feeds for an antenna array, four different beams with the main beam pointing to the ±22 ± 3° and ±43 ± 3° are obtained.     

Notice of Violation of IEEE Publication PrinciplesKa-band distributed MEMS phase shifters on silicon using AlSi suspended membrane

Notice of Violation of IEEE Publication Principles

"Both the authors and the Editor-in-Chief of Volume 13, number 3 of the IEEE/ASME JMEMS (June 2004, pp. 542-549) of the paper numbered JMEMS 1041 have agreed that this paper, "Ka-Band Distributed MEMS Phase Shifters on Silicon Using AlSi Suspended Membrane," should not have been published. The paper would have been withdrawn had this fact been discovered before the IEEE/ASME JMEMS print date for June 2004. The authors have indicated that they will work to provide a new version their paper that will be considered for publication if it is submitted in the future. For help in coming to this decision, I would like to thank those concerned individuals, including the authors, JMEMS editors, and highly respected researchers in the MEMS and microwave communities who contributed their time and consideration to help us assure the integrity of our journal."

Richard S. Muller, Editor-in-Chief, IEEE/ASME JMEMS

This paper presents the design, fabrication, and testing of distributed MEMS phase shifters for Ka-band communication systems. The phase shift can be obtained by changing MEMS bridge capacitors located periodically over the transmission line. Simulation results of phase shifters with various structural parameters are analyzed to develop the optimized designs. The phase shifters are fabricated on the high-resistivity silicon substrate, using suspended AlSi bridge membrane. The measured results demonstrate a phase shift of 286° at 36 GHz with the actuation voltage of 25 V, and a return loss better than 10 dB over 0-40 GHz band. In addition, lifetimes of 3×10/sup 6/ cycles have been achieved for the fabricated phase shifter with all MEMS bridges held to be valid. It shows that AlSi alloy has a nice compromise between strength and resilience.     

A novel dual‐band ring coupler based on dual‐band phase inverter

A novel dual‐band ring coupler based on dual‐band phase inverter is proposed. And two types of dual‐band phase inverters (Type I and Type II) are designed in this article. The design method of dual‐band ring coupler is simpler than the traditional ways like replace the single‐band λ/4 transmission line with dual‐band λ/4 transmission line. Its main idea is replacing the wide‐band phase inverter with dual‐band phase inverter. Two dual‐band ring couplers (0.9/2.88 and 0.9/2.43 GHz) using the two types of dual‐band phase inverter, respectively, are simulated and measured. The measured results validate the proposed method.     

Two‐dimensional beam‐scanning using tapered slot antennas and piezoelectric transducers

A wideband phased array is demonstrated using antipodal exponentially‐tapered slot‐antenna (ATSA) arrays operated by piezoelectric transducer (PET)‐controlled phase shifters. A 4 × 4 ATSA array is designed to scan two‐dimensionally across the entire X‐band. The phase shifters for 2D scanning consist of two sets of multiline phase shifters controlled by the PET for scanning in both planes. The 2D phased array has an antenna gain greater than 8 dBi, including all losses due to the phase shifters and transitions, and shows a wide beam‐scanning capability greater than 30° in both the E‐plane and the H‐plane. © 2006 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2006.