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.     

Circularly polarized stacked patch antenna array with enhanced bandwidth for S‐band applications

In this article, a circularly polarized coupled slot 1 × 4 stacked patch antenna array with enhanced bandwidth is proposed for S‐band applications. Initially, a patch antenna radiating at 2.79 GHz is designed and maximum energy from feedline to patch element is coupled using two rectangular slots. Whereas, a parallel feedline structure is designed to provide polarization flexibility by creating 0, 90 , and 180^o phase differences. Then, a truncated patch element is vertically stacked in the design to achieve broader bandwidth of 600 MHz over frequency range from 2.4 to 3.0 GHz. Finally, a coupled slot 1 × 4 array stacked antenna array having feedline line structure to provide 90^o phase difference for circular polarization is designed and fabricated for measurements. It is observed that the final design achieved target specification having impedance matching (|S₁₁ | (dB) < ?10 dB over 2.4 to 3.0 GHz, broad band circular polarization, and 11.5 dBic total gain. Overall, a good agreement between simulated and measurement results is observed.     

Frequency‐dependent behavioral‐model‐based nonlinear analysis and design of a low‐profile transmit active phased array antenna

Design and behavioral‐model‐based nonlinear analysis of a 3‐GHz active‐phased array antenna (APAA) are presented. Four nonlinear power amplifiers are employed in the output ports of the feeding network (FN) and analyzed based on a 5‐order polynomial model with frequency‐dependent coefficients. The FN is based on 4‐port new Gysel power dividers and combiners arranged in such a way to feed the array with Gaussian‐like amplitude and in‐phase distributions. Beam steering capability is obtained in 2 directions by a new technique including a phase shifter and an amplitude controller (AC). The features result in a low‐profile APAA whose design and fabrication complexity and cost are reduced. Single and 2‐tone power tests are performed to develop analytical expressions in nonlinear region for array factor as a function of the model, FN and the phase and ACs. A similar system with frequency‐independent model is also analyzed for comparison in terms of scan loss, beamwidth, side‐lobe level, beam position, and gain. A microstrip array antenna including the power amplifiers, pre‐amplifiers, AC, delay‐line‐based phase shifters and Gysels is fabricated and measured. The simulation results at the single and dual tones and the intermodulation products are presented which have a good agreement with the measurements.     

Circularly polarized 4 × 8 stacked patch antenna phased array with enhanced bandwidth for commercial drones

This paper demonstrates the design procedure of a 4 × 8 phased array antenna. Initially, a unit element in multilayer topology with orthogonal slots in the ground plane to couple electromagnetic energy is designed. Then, a stacked patch with truncated edges is placed on the top thick substrate layer to enhance the bandwidth to 600 MHz. This multilayered stacked patch unit element is then used to design a 1 × 4 and 4 × 8 slot coupled stacked patch array. On the bottom side, a novel feedline structure is designed to provide a 90 ^o phase difference at the antenna feed for the circular polarization. The phase difference is achieved in the feedline structure using a quarter wavelength ( λ_g/4 ) difference in the lengths. After the numerical validation, both 1 × 4 and 4 × 8 stacked patch antenna arrays are fabricated to validate the simulations. The final 4 × 8 array achieved the target specification of an active reflection of less than ?10 dB over 2.4 to 3.0 GHz, axial ratio of less than 3 dB, and stable radiation pattern over the complete band. In addition, beam scanning characteristics of the proposed stacked patch antenna arrays are also verified. The prototype resulted a peak gain of 19.5 dB at 2.7 GHz, 3‐dB beamwidth around 12 ^o in the xz‐plane, and scanning range of 90 ^o . Overall, good agreement between measured and simulated results showed that the proposed designed array capable of providing 600 MHz is an excellent candidate for the radar communication, small commercial drones, and synthetic aperture radar applications.     

Isolation enhanced circularly polarized patch antenna array using modified electric‐field‐coupled resonator

A modified electric‐field‐coupled (MELC) resonator featuring negative permittivity is proposed to enhance the inter‐element isolation of a circularly polarized (CP) patch antenna array operated at Chinese compass navigation satellite system (CNSS) downlink band. The resonator comprises two capacitive gaps and a common inductive strip connected to the ground plane by two metal vias. A suspended microstrip line excitation is employed to efficiently design and investigate the MELC resonator whose constitutive parameters are subsequently extracted. A dual‐element CNSS antenna array has been prototyped and measured. The experimental results demonstrate that under the assistance of the proposed MELC resonator, a mutual coupling reduction of 15 dB has been achieved while maintaining good impedance matching and CP radiation performance. Details of the design considerations along with simulation and measurement results are presented and discussed.     

High gain substrate integrated waveguide beam scanning antenna with sub‐array elements

A method to enhance the gain of substrate integrated waveguide (SIW) beam scanning antenna is proposed in this article. 2 × 2 SIW cavity‐backed sub‐arrays are employed in array design. The antenna is constructed on two layers. The top layer places four SIW cavity‐backed sub‐arrays as radiating elements and the bottom layer is an SIW transmission line to feed the sub‐arrays. Beam scanning feature can be obtained due to the frequency dispersion. Moreover, through separating radiators to the other layer and using 2 × 2 SIW cavity‐backed sub‐arrays as radiating parts, the antenna gain is improved significantly. For a linear array, 4.1 to 6.8 dB gain enhancement is achieved compared to a conventional SIW beam scanning antenna with the same length. Then, the linear array is expanded to form a planar array for further gain improvement. A 64‐element planar beam scanning array is designed, fabricated, and tested. Experimental results show that the proposed planar array has a bandwidth from 18.5 GHz to 21. 5 GHz with beam scanning angle from ?5° to 11.5° and gain in the range of 20.5 to 21.8 dBi. The proposed high gain beam scanning antennas have potential applications in radar detection and imaging.     

A K/Ka‐band dielectric and metallic 3D printed aperture shared multibeam parabolic reflector antenna for satellite communication

A K/Ka‐band (22‐33 GHz) high‐gain aperture shared multibeam parabolic reflector antenna is proposed. It performs a two‐dimensional beam scanning from a shared single parabolic reflector by introducing off‐focal feeds. The feed array is placed on and off the focal of the parabolic reflector. Traditionally, the feed blockage has a great impact on the performance of the antenna, which reduces the gain and increases the sidelobe level. The purpose of this paper is to suppress the negative effects of feed blockage by using hybrid material processing method. Both dielectric and metallic 3D printing technologies are used for antenna fabrication. The parabolic reflector antenna is printed by selective laser melting using aluminum alloy. The feed array and the supporting structures are printed by stereolithography apparatus in resin to control the blockage. The method helps to suppress the sidelobe level from ?10 to ?15 dB and to enhance gain by up to 2.3 dBi. The reflection coefficient is less than ?10 dB, while the coupling coefficient between the ports is less than ?20 dB over the entire designed band. At 31.5 GHz, the simulated maximum gain of the antenna are 30.7, 29.1, and 29.7 dBi, when different port separately excites. Multiple beams at ±15° and 0° are observed on both E‐ and H‐planes. Besides, it also verifies the possibility to use dielectric and metallic 3D printing technologies in hybrid for microwave device fabrication.     

Design of dual‐band microstrip patch antenna with right‐angle triangular aperture slot for energy transfer application

This work focusing on the dual‐band antenna design with rectifying circuit for energy transfer system technology for enhancement gain performance. The air gap technique is applied on this microstrip antenna design work to enhance the antenna gain. The work begins with designing and analyzing the antenna via the CST Microwave Studio software. After validation on acceptable performance in simulation side is obtained, the return loss, S₁₁ of the antenna is measured using vector network analyzer equipment. The rectifier circuit is used to convert the captured signal to DC voltage. This projected dual‐band antenna has successfully accomplished the target on return loss of ?44.707 dB and ?32.163 dB at dual resonant frequencies for 1.8 GHz and 2.4 GHz, respectively. This proposed antenna design benefits in low cost fabrication and has achieved high gain of 6.31 dBi and 7.82 dBi for dual‐band functioning frequencies.     

A two‐layer beam‐steering array antenna with 4 × 4 modified Butler matrix fed network for switched beam application

This paper presents a novel two layers beam‐steering array antenna fed by a 4 × 4 modified Butler matrix. Each of the radiation elements have been replaced by a collection of 2 × 2 circularly polarized (CP) square patches, which joined together by a modified sequentially rotated feed network. The antenna array consists of 2 × 5 CP square patches, which connected to four ring sequential rotation and fed by butler matrix. The proposed Butler matrix which plays a role as beam‐steering feed network consists of four novel 90° circular patch couplers and two 45° half circular patch phase shifter. Altogether, using of a 2 × 5 phased array antenna and a modified Butler matrix cause to empower array antenna for covering frequency range between 4.67 to 6.09GHz, the maximum gain of 14.98 dB and 3‐dB axial ratio bandwidth of 1.2GHz (4.9~6.1GHz) is attained.     

Design of a subarray with special radiation pattern for low profile wide‐angle scanning phased array

A low profile subarray with a special radiation pattern for the wide‐angle H‐plane scanning phased array is presented. Five parallel dipoles located above a metal ground serve as the radiator. The differential evolution (DE) algorithm is used to obtain the weights for a special radiation pattern, which is realized by a corresponding feed network. The overall dimension of the proposed subarray is only 0.55λ₀ × 0.55λ₀ × 0.14λ₀. The prototype is fabricated and measured, and the measurement results are consistent with the simulation results. Because of the special radiation pattern and compact size, this subarray is suitable as an element in the wide‐angle scanning phased array. A uniform linear array consisting of five proposed subarrays is built in high frequency structural simulator, and the simulated results show that the main beam can scan nearly from ?70° to +70° in the H‐plane with a gain fluctuation less than 3 dB.     

Design of a printed log‐periodic dipole array antenna with high gain for millimeter‐wave applications

In this article, a V‐band printed log‐periodic dipole array (PLPDA) antenna with high gain is proposed. The antenna prototype is designed, simulated, fabricated, and tested. Simulation results show that this antenna can operate from 42 to 82 GHz with a fractional impedance bandwidth of 64.5% covering the whole V‐band (50–75 GHz). The antenna has a measured impedance matching bandwidth that starts from 42 to beyond 65 GHz with good agreement between the experimental and simulated results. At 50 and 65 GHz, the antenna has a measured gain of 10.45 and 10.28 dBi, respectively, with a gain variation of 2.6 dBi across the measured frequency range. The antenna prototype exhibits also stable radiation patterns over the operating band. It achieves side‐lobe suppression better than 17.26 dB in the H‐plane and better than 8.95 dB in the E‐plane, respectively. In addition, the cross‐polarization component is 18.5 dB lower than the copolarization with front‐to‐back ratio lower than 24.1 dB in both E‐ and H‐planes across the desired frequency range. Based on a comparison of performance among the reported work in the literature, we can say that the proposed PLPDA antenna is a proper candidate to be used in many applications at V‐band frequency. © 2014 Wiley Periodicals, Inc. Int J RF and Microwave CAE 25:185–193, 2015.     

Wide‐bandwidth dielectric resonator antenna with omni‐directional radiation patterns for beam focusing properties in a circular array

Investigation results are presented for a cylindrical dielectric resonator antenna (DRA) with a central airgap, which is excited using a coaxial probe connected to a wire monopole. By selecting the proper values of airgap and monopole heights, a desired impedance bandwidth (S₁₁ ≤ ?10 dB) from 40% to 67% can be achieved. The proposed DRA provides monopole like omni‐directional radiation patterns with low crosspolarization levels throughout the bandwidth. Prototype DRA was fabricated with equal heights of the airgap and monopole and experimentally verified for both the impedance matching and radiation performance. Simulated and measured bandwidths of 67% and 64%, respectively, were obtained with acceptable peak realized gain. The simulated and measured radiation patterns agree well. Furthermore, this DRA is investigated for beam focusing properties when implemented in a circular array consisting of four‐elements on a circular finite ground plane. © 2013 Wiley Periodicals, Inc. Int J RF and Microwave CAE 24:92–101, 2014.     

Ten switched‐beams with 2 × 2 series‐fed 2.4 GHz array antenna and a simple beam‐switching network

This article presents a 2 × 2 series fed 2.4 GHz patch antenna array having multiple beam switching capabilities by using two simple 3 dB/90° couplers to achieve required amplitude and phase excitations for array elements with reduced complexity, cost and size. The beam switching performance with consistent gain and low side lobe levels (SLL) is achieved by exciting the array elements from orthogonally placed thin quarter‐wave (λ_g/4) feeds. The implemented array is capable to generate ten (10) switched‐beams in 2‐D space when series fed elements are excited from respective ports through 3 dB quadrature couplers. The dual polarized characteristics of presented array provide intrinsic interport isolation between perpendicularly placed ports through polarization diversity to achieve independent beam switching capabilities for intended directions. The implemented antenna array on 1.575 mm thick low loss (tan δ = 0.003) NH9450 substrate with ε_r = 4.5 ± 0.10 provides 10 dB return loss impedance bandwidth of more than 50 MHz. The measured beam switching loss is around 0.8 dB for beams switched at θ = ±20°, Ф = 0°, 90°, and 45° with average peak gain of 9.5 dBi and SLL ≤ ?10 dB in all cases. The novelty of this work is the capability of generating ten dual polarized switched‐beams by using only two 3 dB/90° couplers as beam controllers.