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.     

一种高增益宽频带圆极化微带阵列天线的研制

针对微带天线阻抗匹配带宽一般较窄的自身缺陷,基于相控阵雷达天线的应用背景,设计了一种工作在X波段的双层圆极化微带天线结构,且优化发现,其各电磁参数良好。为提高其增益,还在此基础上设计并最终制作了双层2×2结构的微带天线阵列,其实测性能与设计值相符,增益达到10.7dB,带宽1.2GHz,相应轴比为4dB,符合圆极化要求。     

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.     

A 2 × 2 array antenna with circular polarization and conical beam radiation

A circular disk patch antenna loaded with a hemi‐circular slot is initially proposed for achieving circular polarization (CP). To exhibit broad CP bandwidth that can cover the WLAN 2.4 GHz operating band, the patch antenna is fed by an L‐shaped probe. To further attain conical beam radiation with peak gain of ～8 dBic at ±30 degrees theta angle (θ), a 2 × 2 array type is proposed in this study, in which four circular disk patch array elements are arranged in a sequentially rotated fashion via a corporate feed network. Here, desirable 3‐dB axial ratio (AR) bandwidth and 10‐dB impedance bandwidth of ～5% and 21% were measured. © 2013 Wiley Periodicals, Inc. Int J RF and Microwave CAE 24:223–228, 2014.     

Circularly polarized beam‐steering antenna array for ultra‐high frequency radio frequency identification applications

A circularly polarized beam‐steering antenna array with Butler matrix is designed in this letter for ultra‐high frequency radio frequency identification applications. To achieve the identification of the fast‐moving tag groups, a 3 × 4 Butler matrix is utilized to switch the radiation directions at ?25°, 0°, and +25°, respectively. Besides, series‐fed patch antenna element is designed and the 1 × 4 antenna array is built with element rotation for a good polarization performance. Finally, the proposed antenna system is fabricated and the identification area and radiation performance are tested.     

Leaky‐wave antenna with high gain and wide beam‐scanning angle range based on novel SIW‐CRLH transmission line

A leaky‐wave antenna (LWA) with high gain and wide beam‐scanning angle is proposed in this article using a novel substrate integrated waveguide (SIW) composite left/right‐handed transmission line (CRLH TL). The novel SIW‐CRLH TL is analyzed and the equivalent circuit model is also provided. Considering the continuous phase constant of the balanced SIW‐CRLH TL from negative to positive values, the proposed LWA can obtain a continuous beam steering property from backward to broadside to forward. For verification, a periodic LWA, which is comprised of 10 unit cells of the balanced SIW‐CRLH TL, is fabricated and measured. The measured and simulated results agree well, showing that the proposed periodic LWA operates from has continuous beam‐scanning capabilities of about 90° from backward to forward (including the broadside) with gains of better than 10 dB within the operating band. © 2015 Wiley Periodicals, Inc. Int J RF and Microwave CAE 26:36–41, 2016.     

A coding optimized polarization conversion metasurface in broadband and wide‐angle

In this article, a coding optimized metasurface is proposed for linear polarization conversion in broadband and wide‐angle. Using an improved coding method, the geometry of the metallic structure and the size of the unit cell are encoded with a code sequence. The code sequence is optimized by genetic algorithm, considering bandwidth, efficiency, and angular stability. In this way, a coding optimized metasurface was obtained for polarization conversion in broadband and wide‐angle. It can convert linear polarized incidence to its orthogonal polarized reflection in 8 to 18.9 GHz and 0° to 45°, with the polarization conversion ratio larger than 80%. Both simulated and measured results demonstrated the effectiveness of the proposed metasurface. Hence, our method offers an effective strategy to design high‐performance polarization conversion metasurfaces.     

A polarization‐reconfigurable array design based on mode combination technique

This article reports a novel polarization‐reconfigurable antenna array using the technique of mode combination (MC). It can electronically alter its polarization states between left‐hand circular polarization mode, right‐hand circular polarization mode, and linear polarization (LP) mode. The antenna array consists of 2 × 2 microstrip antenna elements with one L‐slot on each square patch and two PIN diodes located in the slot region. Instead of degenerating circular polarization (CP) and LP modes by exciting different radiation parts of the antenna element, the LP one is combined by orthogonal CP modes generated by adjacent elements of the proposed antenna array. To verify the concept, a prototype is manufactured and tested. Experimental results show that the proposed antenna has an overlapped ?10 dB impedance bandwidth of around 11.2% for both CP modes and the LP one. The realized maximum gains are around 7.5 dB for the CP modes and 5.6 dB for the LP mode, which are satisfactory for wireless local area network in wireless communication systems.     

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.     

Investigation of ultra‐wideband Bowtie antennas for phased array feed application

In this article, two new ultra‐wideband (UWB) dual‐polarized Bowtie antennas are investigated as the elements for a phased array feed for reflectors. In addition to its UWB impedance matching characteristic, the Bowtie antennas have stable large beam‐width and a low cross‐polar level over a wide frequency band with a compact size, which is an essence for phased array applications. The simulated and measured results state a low ohmic loss, good impedance matching (S₁₁ below ?15 dB) and good radiation performance, with a simple structure for easy manufacturing. The proposed antennas can be good candidates for phased array feed (PAF) in FAST and the SKA (square kilometer array) pathfinder PHAROS2 projects, and massive MIMO antennas in wireless communication systems.     

Wideband microstrip‐fed tapered slot antennas and phased array

Two wideband tapered slot antennas are designed, fabricated, and tested. The first antenna, which is fabricated on a high dielectric constant substrate (?_r = 10.2), shows a measured return loss of better than 10 dB from 1.6 to 12.4 GHz (7.7:1 bandwidth), and an antenna gain varying from 3.6 to 7.8 dBi. The second antenna is built on a low dielectric constant substrate (?_r = 2.2), and demonstrates return loss of better than 10 dB from 1.8 to 15.2 GHz (8.4:1 bandwidth). The second antenna also has improved antenna gain, from 5 to 15.6 dBi, and is used to build a wideband 1 × 4 H‐plane phased array with a total gain of 9–17 dBi and a beam steering angle of ±15° from 3 to 12 GHz. © 2007 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2007.     

Novel wideband metal‐only transmitarray antenna based on 1‐bit polarization rotation element

In this article, a novel wideband metal‐only transmitarray based on 1‐bit polarization rotation element is proposed. First, a novel wideband polarization rotation element is designed, which consists of four metallic layers without any substrate layers. The element can be used to rotate polarization of the transmission wave by 90° with respect to that of the incident wave. The element and its mirror image can provide 0° and 180° phase shifts with 1‐bit phase quantization in the 9.2 to 11.2 GHz band with more than 80% polarization conversion rate. Then, by using the proposed element, a 21 × 21‐element transmitarray with a standard pyramidal horn feed is designed and fabricated. The measured results show that the transmitarray achieves 16.8% 1‐dB gain bandwidth with a peak gain of 21.6 dBi. Its cross‐polarization and side‐lobe levels are below ?20 and ?10 dB, respectively, in the operating band. The measured results agree well with the simulation ones, validating effectiveness of the transmitarray design method.     

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.     

High‐efficiency leaky‐wave antenna with continuous wide‐angle scanning using hybrid composite right/left handed structure

A hybrid composite right/left handed (CRLH) structure based leaky‐wave antenna with continuous wide beam scanning is proposed in this article. Six series‐wound periodic units, combining spoof surface plasmon polariton (SSPP) with CRLH, form the radiating portion of proposed antenna. The unit is connected to the ground with metal hole, which provides the equivalent parallel inductance, and the unit is separated from its adjacent unit at prescheduled intervals, which provides the equivalent series capacitance. Additionally, the unit operates at balanced state and the open stopband is obviously suppressed. Dispersion diagram is also used to analyze this continuous scanning. A prototype of proposed antenna is fabricated and measured. The main beam of the antenna scans continuously from ?70° to +40° in the range from 5.2 to 8.8 GHz. The antenna radiation efficiency reaches a maximum of 92% in the working band. Measurement results agree quite well with the simulation, which indicate this leaky wave antenna can find potential applications in communication systems and radars.     

Design of a broadband dielectric resonator antenna and its application in low sensitivity frequency beam‐scanning array with wide scanning angle and suppressed sidelobes

In this paper, a broadband dielectric resonator antenna (DRA) with a simple H‐slot feeding structure is proposed. The broad bandwidth (~45%) and uni‐directional radiation enable this DRA suitable to work as a radiation element in the construction of a beam‐scanning array with not only low frequency sensitivity which is important for accurate angle estimation of in‐coming targets, but also a wide scanning range. Moreover, stable coupling coefficients are established around all the above three resonances with respect to its corresponding feeding line, ensuring a low sidelobe level (SLL) across the whole operating frequency range. In order to realize such a DRA, a latticed rectangular structure is utilized to generate the lower two resonances, while the upper resonance is generated by its H‐shaped feeding slot. The shape of the latticed dielectric resonator is also modified according to a 3‐D printed fixing structure for an accurate installation. A 20‐element beam‐scanning prototype is demonstrated and manufactured. The range of scanning angle is from ?36° to +13° within the bandwidth of 10 to 16 GHz, corresponding to a frequency sensitivity of only 122.5 MHz/^o. The achieved SLL are smaller than 19 dB for all scanning beams. The above performance indicates that, this array is very suitable for near‐range radar systems requiring an accurate angle estimation.     

基于相控阵技术的新型无源RFID标签理论研究

基于无源超高频射频识别(UHF RFID)系统的基本工作原理,提出了一种新型标签,将相控阵天线引入无源标签,使得标签具有了定位功能,并且可以改善UHF RFID系统的通信距离.对标签相控阵天线各参数进行了理论数值分析,并使用Matlab软件针对不同的天线阵元个数和阵元间距仿真天线波束幅值与方向性参数,进而实现对理论分析结果的验证.结果表明:理论与仿真结果相符.通过仿真确定了合适的相控阵天线参数,为进一步的研究设计奠定了理论基础.     

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.     

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.     

多元高斯声束模型相控阵超声传感器声场仿真

由于高斯函数积分的简单性,利用扩展多元高斯声束模型对矩形相控线阵超声传感器偏转聚焦时的辐射声场进行了理论计算,并在一种介质中与更精确的瑞利积分进行了分析和对比,在偏转角度不是很大的情况下,计算结果非常符合。利用该方法计算了传感器安装在契块上时固体试件中的声场分布,并在入射角大于10°(折射角大于20°)时,对结果进行了修正,使声场计算的偏转范围增大,进一步丰富了高斯叠加方法的适用范围。     

Viewing angle enhanced integral imaging display based on double‐micro‐lens array

A viewing angle enhanced integral imaging display, which consists of a double microlens array, and a display panel is proposed. The double microlens array includes a convex microlens array and a concave microlens array. The display panel is used to display original elemental image array. The convex microlens array, located near the display panel, is used to provide a virtual elemental image array for the concave microlens array. The concave microlens array, located far away from the display panel, is used to display integral images with the virtual elemental image array. Compared with the original elemental image, the pitch for each virtual elemental image is magnified by the corresponding convex microlens. As a result, the viewing angle is expanded. Simulations based on ray‐tracing are performed and the results agree well with the theory.