Magneto-electric Dipole Research Articles

A Low-Profile Dual-Polarized Magneto-Electric Dipole Antenna for 5G Applications

A low-profile dual-polarized magneto-electric dipole (MED) is presented in this communication. The low profile was achieved using meander slots on the vertical magneto dipole, reducing the antenna height to 0.15λ0, where λ0 is the wavelength of the center frequency. Relatively, the proposed MED structure is easier to process and more stable than the traditional low-profile MED structure. The broadband performance for 5G Applications was realized based on MED structure, and the dual-polarization structure has wider coverage area and lower multipath transmission losses. Moreover, the orthogonal feeding structure provides a satisfying isolation between two ports. To verify the simulation results, a prototype of the proposed antenna was fabricated and measured. The results show that the overlapped operating frequency bandwidth with |S11| ≤ −10 dB, |S12| ≤ −20 dB was 36.8% from 3.1 GHz to 4.5 GHz, the peak gain reached 10.2 dBi, and the average gain exceeded 8.5 dBi. The measured 3 dB beamwidth with more than 44 degrees beamwidth was realized in both E-plane and H-plane. In addition, cross-polarization levels below −22 dB that covered the above frequency band were achieved. Compared with other MED antennas, in addition to broadband and high gain, the proposed antenna has the advantages of a low profile, easy processing, and low cost, which make it a competitive candidate for 5G applications.

Broadband Cross-Slotted Patch Antenna for 5G Millimeter-Wave Applications Based on Characteristic Mode Analysis

This article proposes a wideband differentially fed dual-polarized magnetoelectric (ME) dipole for millimeter-wave (mm-Wave) applications. Various electric and magnetic characteristic modes of a slotted patch antenna are investigated and utilized effectively to create a stable broadside radiation pattern, covering fifth-generation (5G) frequency bands from 24.25 to 40 GHz. To implement this, the lifted ground (LGND) concept is applied to achieve a 57.1% impedance bandwidth for a single antenna element. In addition, the three resonances of the antenna can be manipulated independently. The use of differential feeding allows more than 36 dB of port-to-port isolation across the entire operating band. The measured gains of the single element and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2\times $ </tex-math></inline-formula> 2 array are 8.4 and 13.4 dBi, respectively. Also, the measured results indicate symmetrical E- and H-plane radiation patterns and cross-polarization levels lower than −26 dB. With the favorable electrical performance, compact size, simple structure, and low-cost fabrication, the proposed ME dipole is a promising candidate for mm-Wave Antenna-in-Package (AiP) applications.

A 24–30-GHz 256-Element Dual-Polarized 5G Phased Array Using Fast On-Chip Beam Calculators and Magnetoelectric Dipole Antennas

We present a 24–30-GHz 256-element dual-polarization transceiver (TRX) phased array based on a 16-element beamformer integrated circuit (BF-IC), 2-element frequency conversion integrated circuit (FC-IC), liquid crystal polymer (LCP)-based combiners and filters, and a tileable package with 64 embedded dual-polarized (dual-pol) antennas. The phased array presented in this work overcomes three key challenges in current 5G millimeter-wave (mmWave) antenna arrays: 1) it supports a dramatic increase in the number of supported fast-access beams; 2) it offers improved power efficiency; and 3) it provides a path to lower solution cost. 1) We enable fast switching among >30000 beams—orders of magnitude improvement over prior work—by employing an on-chip beam calculator in the BF-IC, achieving 200-ns beam setup and 8-ns over-the-air (OTA)-switching time. 2) We enable a module-level transmitter (TX) mode peak power added efficiency (PAE) of 20% using a modular architecture that preserves power amplifier (PA) linearity and efficiency as well as receiver (RX) mode low noise amplifier (LNA) noise figure (NF). The module achieves Psat effective isotropically radiated power (EIRP) of 68.5 dBm and BF-IC NF < 3.9 dB. 3) We lower the solution cost by enabling a wider steering range to reduce the number of phased arrays required in a sectorized coverage scheme, by reducing the IC and package area, and by avoiding calibration. The wider steering range is enabled by using an in-package magnetoelectric dipole antenna (for the first time in silicon-based phased arrays), resulting in steering over ±70° in H- and V-pol in both E- and H-planes without requiring any calibration. Moreover, the module achieves >20-dB cross-polarization isolation across the entire ±70° beam steering range.

An On-Body Matched Differentially Fed Magnetoelectric Dipole Antenna for Head Imaging Systems

An on-body matched differentially fed magnetoelectric (ME) dipole antenna is proposed for the head imaging system to detect intracranial hemorrhage (ICH). The ME dipole with its differential feed achieves a wide impedance bandwidth of 137% from 0.45 to 2.4 GHz. The antenna exhibits unidirectional and symmetrical radiation patterns in the near-field region, leading to a stable main beam toward the 2-D imaging domain inside the human head. The high front-to-back ratio (FBR) above 18 dB is realized in the whole frequency band by this antenna. The values of specific absorption rate (SAR) always remain safe level under 0.82 W/kg in the entire band with an input power of 10 dBm. To validate the detection capability of the proposed antenna, a head imaging system composed of eight antenna elements in a co-polarization state is designed and fabricated. The reconstructed 2-D images of the head interior using a confocal imaging algorithm demonstrate the successful detection and localization of the circular bleeding area as small as 3 mm in radius numerically and 5 mm in radius experimentally, and it has the capability to detect multiple bleeding areas of the human brain, which indicates the head imaging system has the potential to be used in clinical trials.

Broadband Circularly Polarized Magnetoelectric Dipole Antenna by Loading Parasitic Loop

A broadband circularly polarized (CP) magnetoelectric (ME) dipole antenna loaded with parasitic loop is presented in this communication. The proposed ME dipole antenna is fed through the slot-coupled feeding method, in which a microstrip line is used to couple the energy to the antenna by the slot etched on the ground plane. By introducing a parasitic loop coplanar with the horizontal patch, extra CP modes are generated due to the coupling with the radiation patch. Combining with the original CP mode, the simulated 3 dB axial-ratio (AR) bandwidth is enhanced from 12.2% to 45.8% with an increment of 33.6%. The measured results show that the 10 dB impedance bandwidth is 55.3% (3.4–6.0 GHz) and the 3 dB AR bandwidth is 42.1% (3.62–5.55 GHz). Moreover, the proposed antenna owns flat gain and stable unidirectional radiation patterns within the designated frequency band.

Wideband low‐profile endfire circularly polarized antenna using mode superposition technique

In this article, a wideband low-profile endfire circularly polarized (CP) antenna using magnetoelectric dipole is proposed. Designing a wideband electric dipole element is easy and well-studied in the literature. However, designing a compact wideband magnetic dipole element is still a challenge. In this paper, the impedance bandwidth (IBW) of the magnetic dipole is enhanced by reducing the resonance frequency of higher-order mode half-TE310 with the help of rectangular slots placed at the null of mode half-TE310. By combining the resonance frequency of mode half-TE110 and mode half-TE310, the magnetic dipole can yield a larger IBW (6.86–7.67 GHz, 11.14%) with smaller planar dimensions of 1.259λ0 × 0.363λ0 × 0.038λ0 (λ0 is the free space wavelength at the centre frequency). To generate a wideband endfire CP wave, a horizontally polarized electric dipole with a feed line is combined with the vertically polarized magnetic dipole. The measured IBW and axial ratio bandwidth (ARBW) are 11.65% and 12.02%, respectively, with a measured peak endfire gain of 5 dBic. The overall dimension of the proposed wideband low-profile endfire CP antenna is 1.11λ0 × 0.66λ0 × 0.033λ0.

A Planar 4-Bit Reconfigurable Antenna Array Based on the Design Philosophy of Information Metasurfaces

Inspired by the design philosophy of information metasurfaces based on the digital coding concept, a planar 4-bit reconfigurable antenna array with low profile of 0.15 λ 0 (where λ 0 is the wavelength) is presented. The array is based on a digital coding radiation element consisting of a 1-bit magnetoelectric (ME) dipole and a miniaturized reflection-type phase shifter (RTPS). The proposed 1-bit ME dipole can provide two digital states of “0” and “1” (with 0° and 180° phase responses) over a wide frequency band by individually exciting its two symmetrical feeding ports. The designed RTPS is able to realize a relative phase shift of 173°. By digitally quantizing its phase in the range of 157.5°, additional eight digital states at intervals of 22.5° are obtained. To achieve low sidelobe levels, a 1:16 power divider based on the Taylor line source method is employed to feed the array. A prototype of the proposed 4-bit antenna array has been fabricated and tested, and the experimental results are in good agreement with the simulations. Scanning beams within a ±45° range were measured with a maximum realized gain of 13.4 dBi at 12 GHz. The sidelobe and cross-polarization levels are below –14.3 and –23 dB, respectively. Furthermore, the beam pointing error is within 0.8°, and the 3-dB gain bandwidth of the broadside beam is 25%. Due to its outstanding performance, the array holds potential for significant applications in radar and wireless communication systems.

A Compact Dual-Wideband Magnetoelectric Dipole Antenna for 5G Millimeter-Wave Applications

A compact dual-wideband millimeter-wave magnetoelectric (ME) dipole antenna based on dual-mode operation is proposed in this article. The ME dipole consists of two mirrored U-shaped patches, a substrate integrated waveguide (SIW) cavity with slotted top and two metallized vias connecting the patches to the slot. The two mirrored U-shaped patches work as an electric dipole (E-dipole), while the slot on the top of the SIW cavity and two metallized vias works as a magnetic dipole (M-dipole). In the lower frequency band, <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.5\lambda $ </tex-math></inline-formula> modes of the E-dipole and the M-dipole are excited to form the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.5\lambda $ </tex-math></inline-formula> mode of the ME dipole. In the higher frequency band, <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1\lambda $ </tex-math></inline-formula> modes of the E-dipole and the M-dipole are excited to form the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1\lambda $ </tex-math></inline-formula> mode of the ME dipole. In order to achieve compact structure and wide bandwidths, an SIW cavity is designed to feed the antenna. The proposed design shows that the measured impedance bandwidths (return loss larger than 10 dB) are 24–29.3 and 35.5–43.5 GHz at least with the achieved gain of 4.8–6.1 and 6.8–8.7 dBi, respectively. The designed antenna is suitable for 5G dual-band millimeter-wave applications.

A D-Band Magnetoelectric Dipole Antenna-in-Package (AiP) Implemented on BT-Based Organic Substrate

A high gain, wide bandwidth (BW), and low-profile <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$D$ </tex-math></inline-formula> -band magnetoelectric dipole antenna-in-package (AiP) is proposed in this article. The unit antenna with a cavity backed slot is first evaluated by a substrate integrated waveguide (SIW) feed structure. The simulated impedance BW of the unit antenna covers 27 GHz from 132 to 159 GHz with stable broadside radiation patterns. Then, a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$4\times $ </tex-math></inline-formula> 2 array based on the proposed unit antenna is designed and verified on a four layer BT-based organic substrate. The array design is composed of an isolation, a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2\times $ </tex-math></inline-formula> 2 subarray, a two-way SIW power divider, and a probe pad to SIW transition. The <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2\times $ </tex-math></inline-formula> 2 subarray is realized by a four-way broad wall coupler with a V-junction design in particular. Tested by probing on substrate in the direct far-field chamber, the measured impedance BW covers 23.4 GHz from 135.4 to 158.8 GHz with a peak gain of 14.1 dBi at 150 GHz. The average of measured gains within the 130–160-GHz band is 12 dBi. Modeled with the dimensions of structural analysis results from optical microscope (OM) and cross-sectional scanning electron microscope (SEM) inspection, the post-simulation result shows a good agreement with the measurement result, including impedance BW, radiation patterns, and gains. This article demonstrates that the proposed AiP using the low-cost BT-based substrate manufacturing technology can be a good candidate for the future <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$D$ </tex-math></inline-formula> -band applications.

A broadband and low‐profile magnetoelectric dipole antenna with low radar cross section

AbstractIn this study, a novel broadband and low profile magnetoelectric dipole (MED) antenna with a low radar cross section (RCS) is proposed. The 10 dB RCS reduction is achieved by shifting the reflected energy to six directions, which is an efficient optimization method based on convolutional operations. Specifically, the polarization conversion metasurface (PCM) unit with high polarization conversion rate is constructed and employed in the MED antenna for RCS reduction. The proposed antenna is fabricated and measured. Measured results depict that the low RCS antenna offers good impedance matching in 12–15.6 GHz (relative bandwidth 26%). Compared with the reference antenna, the RCS of the proposed antenna is reduced by more than 10 dB from 9.9 to 16 GHz. It is proved that the proposed antenna has broadband and stable radiation performance and outstanding specular reflecting suppression capabilities.

Compact planar magneto‐electric dipole‐like circularly polarized antenna

A novel circularly polarized (CP) substrate integrated magneto-electric dipole (MED) antenna has been designed for appropriate wireless communication. The antenna comprises two printed radiating arc-shaped patches and a feeding strip on top, two rows of embedded metallic vias, and a ground plane. A coax probe is used to excite the patches and via rows simultaneously with the help of a printed feeding strip. Finally, the antenna design has been prototyped and its performance experimentally was verified in terms of impedance bandwidth, axial-ratio (AR), gain, efficiency, and radiation patterns. The measured impedance bandwidth (under −10 dB) and AR bandwidth (under 3 dB) are 6.15–7.01 (13%) GHz and 6.24–6.40 (2.53%) GHz respectively. Typically, the measured gain value within 3-dB AR bandwidth at 6.3 GHz is 4.5 dBic with average measured in-band antenna efficiency of 85.2%. Moreover, the proposed antenna shows an acceptable agreement with predicted counterparts, including unidirectional radiation patterns.

Pin‐loaded ultrathin magnetoelectric dipole antenna with unidirectional radiation

AbstractA wide‐beam magnetoelectric dipole antenna with an ultralow profile of 0.01λ0 is proposed in this letter. The magnetic dipole (M‐dipole) is formed by placing a turnstile‐shaped patch above a circular ground, establishing the foundation of a thin profile. Then, a pair of crossed strips with one end shorted is introduced, exciting the electric‐dipole without affecting the radiation of M‐dipole and increasing the antenna profile. In that way, stable wide‐beam unilateral radiation in both the E‐ and H‐planes can be achieved. At the same time, a high front‐to‐back (F/B) ratio of 22 dB is obtained for the measured result. Besides, by adjusting the number and position of shorting pins, the proposed antenna shows beam steering capability, which makes it quite promising for future scanning applications.

Principle and Unified Design of Circularly Polarized Quadruple Inverted-F Antenna With Miniaturized Size and Enhanced Front-to-Back Ratio

The fundamental working principle of front-to-back ratio (FTBR) enhancement of the quadruple inverted-F antenna (QIFA) is clearly revealed for the first time, and a unified design method is then proposed in this article. The characteristic mode analysis (CMA) demonstrates that the QIFA actually operates in two orthogonal modes, and analytical derivation validates that each mode acts as a pair of parallel magnetoelectric (ME) short dipoles for radiation. More specifically, the FTBR of the antenna is determined by the amplitude ratio and phase difference of the two pairs of equivalent ME dipoles. The equivalent model and analytical method can greatly facilitate the design. First, by leading or lagging phase of either characteristic mode through excitation, the beam direction can be flexibly prescribed as forward and backward. Second, the bending direction and bending degree of radiators, respectively, determine the phase and amplitude of its equivalent magnetic dipole, by which the FTBR can be improved. A practical design is carried out with the proposed method, and the antenna achieves an electrically small size of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.068\lambda _{0} \times 0.068\lambda _{0} \times 0.052\lambda _{0}$ </tex-math></inline-formula> and an FTBR of 12.3 dB.

Circularly Polarized Millimeter Wave Frequency Beam Scanning Antenna Based on Aperture-Coupled Magneto-Electric Dipole

Based on the newly suggested wideband circularly polarized (CP) aperture-coupled magneto-electric dipole (MED), a millimeter-wave (mm-wave) frequency-scanned array (FSA) is proposed in this article. The MED is printed on two substrate layers. The electric dipole is two metal patches with perturbation structure, while the magnetic dipole is two rows of metal vias passing through the top substrate layer. The electric and magnetic dipoles, fed by a coupling slot, excite CP wave. By loading an arc-shaped vias row (AVR) at both ends of the magnetic dipole, the CP bandwidth with axial ratio (AR) less than 3 dB is extended to 40.9%. A new compact wideband transition from the rectangular waveguide (RWG) to the substrate integrated waveguide (SIW) is suggested as the feed structure for the CP FSA. A slow wave structure is etched on the ground of SIW to widen the beam scanning range. A 16-element array is designed and measured. The measured results show that the beam scanning range is 56° over 23–33 GHz band with a peak gain of 19.5 dBi. The CP mm-wave FSA has the advantages of wide scanning angle, low profile, and easy fabrication.

A Wideband Low-Cost Reconfigurable Reflectarray Antenna With 1-Bit Resolution

A wideband 1 bit reflectarray antenna (RA) with two-dimensional (2-D) electronically beam-scanning capability is presented in this article. Based on the basic structure of the magnetoelectric (ME) dipole antenna, a novel reconfigurable RA (RRA) element is proposed for wideband operation by combining electric dipole resonance and magnetic dipole resonance. Each element is integrated with only one p-i-n diode to change the types of resonances, leading to a reconfigurable reflecting phase with a 1 bit resolution. As a demonstration, a wideband electronically RRA with 16 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times16$ </tex-math></inline-formula> elements is developed, fabricated, and measured. In the proposed RRA, each element is connected with a separate bias line to independently control the working state and reflecting phase. Measured results show that the proposed RRA can achieve a 3 dB gain bandwidth of 38.4% with a peak aperture efficiency of 24% at 12 GHz. Besides, the proposed antenna can support the wide scanning angles ranging from – 60° to + 60° in the E-plane and 0° to + 60° in the H-plane within the whole operating bandwidth. The proposed simple design could be a promising candidate for intelligent reflective surface (IRS) applications.

Cost-Effective Surface-Mount Magnetoelectric Dipole Antenna Based on Ball Grid Array Packaging Technology for 5G Millimeter-Wave New Radio Band Applications

This article presents a cost-effective miniature surface-mount magnetoelectric (ME) dipole antenna. The antenna is realized by a single-layer FR4 substrate and combined with ball grid array (BGA) packaging technology to achieve miniaturization in size. Due to BGA packaging technology, the surface-mount capability allows interconnection between the proposed antenna and other surface-mount devices using a flip-chip interconnect technology, replacing bulky connectors. The proposed antenna element is very compact. Specifically, the electric dipole of the proposed antenna consists of four patches, whereas the magnetic dipole consists of two rows of plated through-holes and a metal ground between them. In addition, the electric and magnetic dipoles are simultaneously excited by an L-shaped metal probe. The prototype has been manufactured and carefully verified. Experimental results show that the proposed antenna element has a −10-dB bandwidth of 23% in the range of 25–31.5 GHz and achieves a peak realized gain of 6.98 dBi at 26 GHz. The dimensions of the proposed antenna element are only 5 mm <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times $ </tex-math></inline-formula> 5 mm <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times1.8$ </tex-math></inline-formula> mm. The proposed antenna elements can be widely used in the 5G millimeter-wave N257 (26.5–29.5 GHz) and N261 (27.5–28.35 GHz) bands.

A Wideband 2-Bit Transmitarray Antenna for Millimeter-Wave Vehicular Communication

A wideband transmitarray antenna based on the magnetoelectric (ME) dipole element and 2-bit phase compensation scheme is presented for vehicular communications in this paper. A wideband 90° phase shifter is proposed and combined with the rotating method to achieve four discrete phase states. Thanks to the polarization-twisting technique and the simple structure of the phase shifter, the proposed element can be easily designed. For the transmitarray design, a multi-frequency phase compensation strategy is applied to guarantee stable performance over the operating band. To validate the design, a 12 × 12 transmitarray antenna simultaneously covering vehicle-to-satellite band (20 GHz), and 5G millimeter-wave (mmWave) bands (24 GHz/28 GHz) is designed, fabricated and measured. The experimental results show that the prototype can achieve high aperture efficiencies (>40%) within a wide bandwidth (34%). The measured peak aperture efficiency is up to 53% at 23 GHz. These results demonstrate that the proposed 2-bit transmitarray antenna enjoys the advantages of wide operating bandwidth, high aperture efficiency and comparatively low design complexity. With these characteristics, the proposed transmitarray antenna can be a promising candidate for vehicular communications that require reliable satellite links and 5G millimeter-wave connections simultaneously.

A Wideband Low-Profile Reconfigurable Transmitarray Using Magnetoelectric Dipole Elements

A wideband 1 bit reconfigurable transmitarray antenna (RTA) with low-profile characteristic is presented. First, a wideband element for the RTA is designed by combining two centrally fed magnetoelectric (ME) dipoles. Two p-i-n diodes are integrated within the element to achieve 1 bit reconfigurable phase states. Next, the folded scheme is adopted to achieve multiple reflections between the feed source and the RTA, and thus, the height-to-diameter ratio (H/D) is reduced to about one-third of that of the conventional transmitarray. A reflective surface with polarization conversion function is designed beneath the RTA around the source, the unit cell of which is a special <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$C$ </tex-math></inline-formula> -shaped polarizer operating over a wide frequency band. Finally, a low-profile RTA with <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$12 \times \mathbf {12}$ </tex-math></inline-formula> elements is designed, fabricated, and measured. The whole structure has an aperture size of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mathbf {5}.\mathbf {75} \boldsymbol {\lambda }_{\mathbf {0}}\times \mathbf {5}.\mathbf {75} \boldsymbol {\lambda }_{\mathbf {0}}$ </tex-math></inline-formula> , and H/D is 0.28. Measured results show that the proposed RTA has the beam-scanning capability to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\pm \mathbf {40}^{\circ }$ </tex-math></inline-formula> in both E- and H-planes over a bandwidth of 32%. The realized gain is up to 19 dBi and the peak aperture efficiency is 20.5%.

A Wideband Dual-Polarized Magneto-Electric Dipole Transmitarray With Independent Control of Polarizations

This communication presents a dual-polarized transmitarray antenna with wide bandwidth and independent beam control for each polarization. A new low-insertion-loss transmitarray element allowing wideband dual-polarized operation is proposed by using magnetoelectric (ME) dipole with shared radiating structure and interleaved orthogonal feeding probes; 1 bit phase adjustment can be realized individually for each polarization with additional freedom in manipulating the cross-polarization over a fractional bandwidth of 23%. Three transmitarrays that achieve possibly different collimated beams and/or cross-polarization manipulation are designed and carried out at millimeter-wave frequencies covering from 23.5 to 32.5 GHz. Measurement results of the prototypes agree reasonably well with simulations, which validates the wideband operation and independent beam controls.

WCA-Based Low-PSLL and Wide-Nulling Beampattern Synthesis for Radar Applications

There are many unavoidable array errors in practical scenarios, which would drastically increase the sidelobe level (SLL) and distort the performance of radar systems accordingly. In this paper, an effective beampattern synthesis approach is proposed to realize a low peak sidelobe level (PSLL) and wide-nulling in the presence of array errors, thus improving the consequent performance of the radar. In particular, the covariance matrix of the sidelobe region (CMSR) is incorporated into the optimization. Considering the randomness of array errors, the statistical mean method is adopted to obtain a more accurate calculation of the CMSR in the presence of array errors based on a Monte Carlo trial. To efficiently and effectively solve the optimization problem, an advanced metaheuristic algorithm, i.e., the water cycle algorithm (WCA), is adopted when seeking the corresponding optimal weight vectors. Numerical results are provided and discussed to demonstrate the effectiveness of the proposed approach including the results based on a wideband linearly spaced magneto-electric (ME) dipole array.