Dual frequency microstrip phased array with hybrid phase shifter

This paper presents a new concept of the phase shifter design called a hybrid phase shifter. The proposed hybrid phase shifter consists of an analog-type active phase shifter and a digital-type passive phase shifter. To verify the idea the circuit is designed using 0.13-μm RF CMOS technology at 22–26-GHz UWB frequency band. The hybrid phase shifter has the continuous phase shift range up to 25.40, which is able to cover almost two times of the designed analog or digital phase shifter range. The gain drift of about −2.0 dB to 0.7 dB at 24-GHz is observed during phase shift. The simulation results confirm that the proposed hybrid phase shifter can be a good candidate as one of the phase shifter for the implementation in active phased array or multi-antenna beamforming system.

Beam-steering antennas are the ideal solution for a variety of system applications, it is most commonly achieved through using phased arrays, where phase shifters are used to control the relative of the main-beam. In this paper, a low-cost directive beam-steering phased array (DBS-PA) antenna using switched line phase shifters is demonstrated. The proposed DBS-PA antenna has four micro-strip patch antennas, three power dividers and four phase shifters printed on the same Rogers RT-Durroid substrate with a dielectric constant of 2.2 with dimensions of 8 × 3.5 cm. The phased array antenna has a directivity of 15 dBi and the main beam direction can be switched between the angles of ±30 degrees with a 3dB beam-width of 25 degrees. All design and simulations have been carried out using Agilent AdS and Ansoft HFSS software tools. The frequency considered for the operation is 10 GHz.

PurposeThis paper aims to design a radio frequency micro-electro-mechanical system (RF MEMS)-based phase shifter using chamfered coplanar waveguide (CPW) transmission line (t-line) with open-circuit interdigital metal–air–metal (ID MAM) capacitors.Design/methodology/approachThe proposed phase shifter achieves maximum differential phase shift with low loss at Ku band. The phase shifter is built with one switchable fixed-fixed beam (MEMS switch) on chamfered CPW t-line in series with two planar open-circuit ID MAM capacitors. An equivalent circuit model for the proposed phase shifter is derived, and its parameters are extracted using an electromagnetic (EM) solver.FindingsThe MEMS switch is actuated using an electrostatic method with the calculated residual stress of 44.26 MPa. The fabricated phase shifter exhibits low insertion loss, close to 0.14 dB at 17 GHz, with the maximum phase shift of 15.06°. The return loss is greater than 23 dB between 12 and 18 GHz.Originality/valueThis phase shifter presents a promising solution for low loss applications in the Ku band with a maximum phase shift. As the maximum phase shift of 15.06° is achieved for a unit cell with low insertion loss, the phase shifter is found to be feasible for modern electronically tunable phased arrays used for satellite communication and radar systems.

Electric field tunable ferroelectric materials have attracted extensive attention in recent years due to their potential applications for tunable microwave device such as tunable filters, phased array antennas, delay lines and phase shifters (Maiti et al. 2007a; Rao et al. 1999; Romanofsky et al. 2000; Varadan et al 1992.; Zhi et al. 2002). Ba1-xSrxTiO3 and BaZrxTi1−xO3 have received the most attention due to their intrinsic high dielectric tunability. However, the high inherent materials loss and high dielectric constant has restricted its application in tunable microwave device. Various methods have been investigated to lower the dielectric constant and loss tangent of pure ferroelectrics. Forming ferroelectric-dielectric composite is an efficient method to reduce material dielectric constant, loss tangent and maintain tunability at a sufficiently high level. For binary ferroelectric-dielectric composite (such as BST+MgO) (Chang & Sengupta 2002; Sengupta & Sengupta 1999), with the increase of dielectrics content, the dielectric constant and tunability of composites decrease. In order to decrease the dielectric constant of binary composite, it is necessary to increase the content of linear dielectric, and the tunability will decrease inevitably due to ferroelectric dilution. Replacing one dielectric by the combination of dielectrics with different dielectric constants and forming ternary ferroelectric-dielectric composite can decrease the dielectric constant of composite and maintain or even increase the tunability. This is beneficial for tunable application. The Ba0.6Sr0.4TiO3-Mg2SiO4-MgO and BaZr0.2Ti0.8O3-Mg2SiO4-MgO composites exhibited relatively high tunability in combination with reduced dielectric permittivity and reduced loss tangent (He et al. 2010, 2011). With the increase of Mg2SiO4 content and the decrease of MgO content in Ba0.6Sr0.4TiO3-Mg2SiO4-MgO composite, the dielectric constant decrease and the tunability remain almost unchanged. For BaZr0.2Ti0.8O3-Mg2SiO4-MgO composite, an anomalous relation between dielectric constant and tunability was observed: with the increase of Mg2SiO4 content (>30 wt%), the dielectric constant of composite decreases and the tunability increases. The anomalous increased tunability can be attributed to redistribution of the electric field. Ba1-xSrxTiO3-Mg2TiO4-MgO can also form ferroelectric (Ba1-xSrxTiO3)-dielectric (Mg2TiO4-MgO) ternary composite and the dielectric constant can be decreased. With the increase of Mg2TiO4 content and the decrease of MgO content, the tunability of Ba1-xSrxTiO3Mg2TiO4-MgO composite increase. The multiple-phase composites might complicate method to effectively deposit films, particularly if the dielectrics and ferroelectric are not compatible for simultaneous deposition or simultaneous adhesion with a substrate or with

Coplanar 4-bit phase shifters for W-band operation at 94 GHz have been developed using PM-HEMTs as switching elements. The phase shifter MMIC uses double stub loaded lines and branch line couplers. A two-stage variable gain cascode amplifier was integrated with the phase shifter. This combination has insertion gain of 2-8 dB and occupies an area of 1.5/spl times/4 mm/sup 2/. A redesigned version of the phase shifter occupies 1/spl times/2.5 mm/sup 2/ chip area, and has a standard phase deviation of less than 2.1/spl deg/ for all phase states.

This paper presents a novel broadband comparator network design operating at X-band. A multilayer aperture coupling scheme and shielding around the microstrip structures are utilized to achieve broadband performance. There are two main building blocks of the proposed comparator network. These are a quadrature hybrid coupler and a 90-degree phase shifter. These two main components are designed to have broadband performance so that the designed comparator would also have wideband performance. The proposed quadrature hybrid coupler achieves more than 19.7 dB return loss, a 0.75 dB amplitude imbalance, and 1.4 ° phase imbalance along the frequency band 5 GHz to 10 GHz. The 90-deg. phase shifter has less than -10 dB S11 in addition to having less than 1.6 °. phase error and 1.5 dB insertion loss within the frequency band 5 GHz to 9.9 GHz. The proposed comparator is acquired by combining the multiple quadrature hybrid couplers and phase shifters. The results of the manufactured and simulated comparator agree well with each other. The impedance bandwidth (VSWR<2) of the manufactured comparator is <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\%$</tex-math></inline-formula> 61 and operates from 5.26 GHz to 9.9 GHz. An 8x8 microstrip patch antenna array is designed and manufactured to verify the comparator network's sum and diff pattern forming capability. The far-field measurements of the proposed comparator combined with the 8x8 antenna array indicate that 36 dB null depth is acquired at the azimuth plane, and 40 dB null depth is achieved at the elevation plane.

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The present study discusses the design of microelectromechanical systems (MEMS)-based phase shifters and their application in phased array antenna (PAA) realization. Commercially available MEMS Single-Pole-Double-Throw (SPDT) switches have been employed for the phase shifter design at a frequency of 5.7 GHz (ISM band). These phase shifters are in turn integrated with the feed lines of a 4 × 1 planar patch antenna array such that electronic mode of antenna beamsteering is resulted. It has been observed that a progressive phase shift of 45° between successive patch antenna elements would generate 11° beam tilt with good directivity and a high gain of 9.5 dB. The entire PAA structure along with the antenna elements, phase shifter modules, and the corporate feed network are integrated on the same PCB laminate, Rogers Ultralam 2000™ having permittivity e r = 2.5, thickness h = 30 mil (0.762 mm), and a dissipation factor tan δ = 0.0019 in order to facilitate simplicity in fabrication process.

This paper presents a novel design of a low-loss, reconfigurable broadband phase shifter based on groove gap waveguide (GGW) technology. The proposed phase shifter consists of a folded GGW and three bends with a few pins forming the GGW and one bend attached to a movable plate. This movable plate allows for adjustments to the folded waveguide length, consequently altering the phase of electromagnetic waves. The advantage of GGW technology is that it does not require electrical contact between different parts of a structure. Therefore, it enables the moving parts to slide freely without electromagnetic energy leakage, resulting in improved insertion loss in high-power applications. In addition, in the proposed design, the position of the input and output waveguide ports of the phase shifter remains fixed, which is advantageous from a practical point of view. As shown by measurement and simulation results, there is nearly 37% impedance bandwidth with the highest insertion loss of 0.6 dB, and the developed device has a maximum phase shift of 770° at the center frequency of 13 GHz. The phase shifter can be used for various radar and satellite applications that require phase control, such as beamforming networks and phased array antennas.

Known designs of Ka-band phased array antennas incorporate an optical feed or a radial waveguide feed. Significant disadvantage of an optical feed is microwave energy overflow through antenna aperture, which decreases aperture efficiency and increases a side lobe level. Optical feed requires additional space for feeding antenna location and increases overall antenna dimensions. The design of a phased array with a radial waveguide feed forces placement of the phase shifter control circuits outside the dimensions of the array and increases overall antenna dimensions. The purpose of the article is to design a Ka-band phased antenna array (PAA) with a waveguide feed with smallest overall dimensions and various aperture shapes. The manufactured prototype of PAA with a grid pitch of 6x6 mm and size of 300x40 mm showed acceptable results of the side lobe level, scanning sector ±45° and gain factor. Proposed Ka-band phased array antenna design allows one to construct the extremely compact radar of various types including airborne radars.

This paper presents the design of an electronically scanning phased array antenna which is constituted using 130 RF MEMS capacitive switches conflated with a series of linearly placed micro strip rectangular inset feed patch antennas and a corporate feed network. The design and analysis is performed in Ansoft HFSS (version 13.0). As the urge of obtaining high radiation pattern, light weight, low cost and better performance over wide range of frequencies, the micro strip antennas is still in demand. A phased array antenna using high-Q metal-insulator-metal capacitors which are intended as loading elements in the phase shifter have been designed in this context. The simulated result sights the designed 4-bit DMTL phase shifter which provides nearly 22.5°/45°/90°/180° phase shifts for different combination of MEMS switches. The design is optimized for Ku band at 15 GHz and the return loss for the phased array antenna is annexed to be -27.41dB. A highly integrated structure has been designed on silicon substrate having an area of 3.1×1.9cm2 only.

Today's phased-array antennas use hundreds of radiating elements that use relatively high-loss phase shifters that operate over a limited bandwidth. The number of elements and the phase shifter losses affect the overall cost of the antenna system. Ferroelectric RF phase shifters have the potential to meet the low-loss, low-cost requirements driving many phased-array applications. Some of the issues affecting the development of ferroelectric phase shifters include ferroelectric tunability, dielectric losses, conductor losses, and impedance mismatch. We used the measured tunability (250 kHz, room temperature), dielectric constant, and loss tangent (10 GHz, room temperature) of Ba1-xSrx/TiO3 (0.4x 0.6) with various amounts of MgO additive, 0 to 60 wt.%, to estimate the device performance of microstrip phase shifters. The electromagnetic model of the microstrip (which uses a standard 3-mil-wide 1-oz. copper line, 3-mil-thick BST/MgO composite and the bias criteria of 2 V/μm) has produced performance benchmarks for a number of composites providing 360° of phase shift. While the accuracy of the electromagnetic model used to evaluate these materials has limitations, the results do provide some insight as to which materials may be better suited for 10-GHz phase shift devices.

Fast beam steering phased-array antenna based on liquid crystal

Abstract- Design and simulation of a very small size 6-bit DMTL phase shifter is presented. The idea is based on using both capacitor and resonator type methods simultaneously in a phase shifter. The capacitor section creates less significant bits. The bits in this section start from the least significant bit, with 5.625-degree steps. The resonator section creates the bits with 90-degree steps. CPW transmission line is used as an impedance matching between two type phase shifters. The structure is calculated and simulated at the Ka-band using MATLAB and HFSS softwares, respectively. The proposed method decreases the number of cells, considerably. As a result, the size and loss is decreased. The design can be easily scaled to other frequencies for satellite and radar systems.

A 94-GHz phased array antenna using a log-periodic antenna has been developed on a GaAs substrate. The developed phased array antenna comprises four log-periodic antennas, a phase shifter, and a Wilkinson power divider. This antenna was fabricated using the standard microwave monolithic integrated circuit (MMIC) process including an air bridge for unipolar circuit implementations on the same GaAs substrate. The total chip size of the fabricated phased array antenna is 4.8 mm × 4.5 mm. Measurement results showed that the fabricated phased array antenna had a very wide band performance from 80 GHz to 110 GHz with return loss characteristics better than -10 dB. In the center frequency of 94 GHz, the fabricated phased array antenna showed a return loss of -16 dB and a gain of 4.43 dBi. The developed antenna is expected to be widely applied in many applications at W-band frequency.