Transmitarray Antenna Research Articles

A low-side-lobe folded transmitarray antenna based on metasurface with independent amplitude/phase control

In this paper, a low-side-lobe folded transmitarray antenna (LSLFTA) based on metasurface (MS) that can independently control amplitude and phase is proposed. An MS, composed of two vertically placed polarization gates, can realize the efficient reflection of y-polarized waves, efficient transmission of x-polarized waves, and independently control of phase and amplitude is designed for the top surface. A polarization conversion surface (PCS) using an open resonant ring that can efficiently achieve cross polarization conversion is presented. The feed antenna is placed on the center of the top surface to obtain an accurate electromagnetic amplitude distribution. To the best of our knowledge, our work is thus the first one to achieve low-side-lobe FTA. The LSLFTA operating at 14.5 GHz is fabricated and measured to verify the design. After adding amplitude modulation (Taylor distribution), the side lobe level (SLL) is 5.2 dB and 7.5 lower than that of only phase modulation in the yoz plane and xoz plane, respectively. The 3 dB gain bandwidth of the antenna is 19.4% (13.5∼16.4 GHz), and the maximum aperture efficiency is 25.8%. Our work is a promising candidate in the design of high-gain, low SLL, and low-profile antenna.

Mainlobe deceptive jammer suppression with DEPC-MIMO radar with joint transmit–receive design

This paper investigates the problem of mainlobe deceptive jammer suppression via joint transmit–receive design in a multiple-input multiple-output (MIMO) radar. At the design stage, a discrete element-pulse coding (DEPC) phase is implemented in both the slow-time pulses and transmit array antennas. After decoding and compensation of the delayed pulses, the true and false targets can be identified in the joint transmit–receive (JTR) spatial frequency domain. Furthermore, to eliminate the false targets, a data-dependent beamforming technique is adopted, where an optimization problem is constructed to maximize the output signal-to-interference-plus-noise ratio (SINR) by optimizing the DEPC coefficients and the weight vector of the receive filter in an alternating way. Specifically, two methods, including the Single Jammer Suppression (SJS)-Alternating Direction Method of Multipliers (ADMM) and Multiple Jammers Suppression (MJS)-Gradient Descent (GD) methods are developed for the cases of a single jammer and multiple jammers, respectively. A series of numerical results are utilized to verify the effectiveness of the proposed methods for mainlobe deceptive jammer suppression.

An Ultralow-Profile Folded Transmitarray Antenna with Both-Sides Beam Regulate for K-Band Circularly Polarized OAM Waves

An Ultralow-Profile Folded Transmitarray Antenna with Both-Sides Beam Regulate for K-Band Circularly Polarized OAM Waves

Enhanced Precision in Beam Pattern Synthesis for Compact Transmitarray Antenna Design: Integrating Comprehensive Unit Cell and Measurement Environment Models

Enhanced Precision in Beam Pattern Synthesis for Compact Transmitarray Antenna Design: Integrating Comprehensive Unit Cell and Measurement Environment Models

Multifunctional Folded Transmitarray Antenna (MFTA) with Independent Control of Beam and Polarization Using Reconfigurable Metasurface

AbstractWith the rapid development of information and communication technology, intelligent wireless systems have a huge demand for devices with multi‐function integration and multi‐degree of freedom electromagnetic control. In this paper, a multifunctional folded transmitarray antenna (MFTA) using a reconfigurable metasurface is proposed to achieve simultaneous and independent modulation of beam and polarization. The beam scanning, arbitrary wave generator, and polarization conversion functions can be achieved only by adjusting the PIN diode bias on the reconfigurable metasurface. In order to prove the feasibility of the proposed method, a prototype is fabricated and verified by experiments. Both simulated and measured results verify the excellent performance of the MFTA. This work opens a door to multi‐functional integration and multi‐degree of freedom electromagnetic manipulate devices, which have great prospects in areas such as radar detection and wireless communication.

Design and Verification of a Miniaturized Multifunctional Transmitarray Unit Cell for the S-Band

In this paper, a miniaturized multifunctional unit cell structure of a transmitarray operating at S-band and its verification method using a waveguide structure is presented. The unit cell of a multifunctional transmitarray antenna is a critical component because it controls the phase and polarization of an incident wave. The proposed unit cell consists of three main parts: an Rx antenna, a Tx antenna, and a control circuit for phase and polarization. The performance of the designed unit cell is verified by a rectangular waveguide structure. The waveguide structure feeds an electromagnetic wave propagating in a TE<sub>10</sub> mode to a 1 × 2 unit cell array to verify polarization and phase shifting capability of the unit cell. The phase shifting and polarization conversion capabilities of the proposed unit cell are directly measured by the radiation patterns and polarization of the transmitted wave.

Profile reduction of folded transmitarray antenna using multiple feeders

Abstract In this paper, we introduce a novel design for a high-gain, low-profile quad-feed folded transmitarray antenna (FTA) to enable a more compact system. The proposed antenna system consists of a transmitarray, a reflectarray, and four identical planar microstrip U-slot patch antennas placed on the same surface of the reflectarray with an adjacent distance greater than 1λ. To compare the effectiveness of our design, we developed three different antenna array systems with the same aperture size: a single-feed transmitarray antenna (TA) system, the proposed quad-feed FTA system, and a single-feed FTA system. Our experimental results demonstrate that employing four symmetrical feeders with an adjacent distance of 3.2λ effectively reduces the height by about 76.7 % in comparison to the height of a single-feed TA, and by 30 % when compared to the height of a single-feed FTA. We also present the design, fabrication, and testing of a prototype of the proposed quad-feed FTA operating in the Ku-band. The measured results of the prototype confirm the effectiveness of our design.

High-Gain Omnidirectional Transmitarray Antenna

High-Gain Omnidirectional Transmitarray Antenna

A Wideband Low-Profile Folded Transmitarray Antenna Based on Magnetoelectric Dipole Elements

A Wideband Low-Profile Folded Transmitarray Antenna Based on Magnetoelectric Dipole Elements

Wideband High-Efficiency Transmitarray Antenna Using Compact Double-Layer Dual-Linearly Polarized Elements

In this letter, we propose a wideband high-efficiency transmitarray antenna (TAA) consisted of compact double-layer dual-linearly polarized elements. By loading L-shaped branches and four vias, these elements achieve a low transmission loss and full phase shift in a wide frequency band. Then, an optimization method for calculating the wideband average element loss is introduced, which determines the element distribution on the transmitarray aperture. For verification, a TAA prototype consist of 400 elements is fabricated and measured. The peak gain and aperture efficiency measured at 12 GHz are 27.1 dBi and 52.5%, respectively. The measured 1-dB gain bandwidth is 20.4% and the minimum aperture efficiency achieved across the 1-dB gain bandwidth is 33%. The results reveal that the proposed TAA exhibits the advantages of flat gain bandwidth, high aperture efficiency, low profile, and low cost, endowing it with the potential for conformal applications and the capability to reliably connect satellite links as a communication antenna.

A Broadband Filtering Circularly Polarized Folded Transmitarray Antenna Based on Metasurface

This letter presents a broadband filtering circularly polarized (CP) folded transmitarray antenna (FTA) with a linearly polarized (LP) feed antenna based on metasurface (MS). The whole antenna mainly consists of two MSs located on the top and bottom layers and an LP feed antenna. LP to CP wave (LP-CP) conversion and phase compensation are achieved across the entire X-band with the designed top MS. The top bandpass MS is also used as a spatial filter, utilizing its out-of-band suppression characteristics and high passband edge selectivity. A fabricated prototype was measured, and the results reveal that its maximum gain is 27.8 dBi at 10.2 GHz with an aperture efficiency of 40%. It also achieves a 3-dB gain bandwidth of 24.5% and a 3-dB axial-ratio (AR) bandwidth of 41.1%, which is in good agreement with the simulation results as well. The proposed broadband CPFTA achieves a bandpass filtering response while also retaining the advantages of low profile, high gain, and low cost, which illustrates great application potential in future wireless communication systems.

Multi-beam high gain steerable transmitarray lens for satellite communication and 5G mm-Wave systems

This paper presents the design of a high gain multi-beam transmitarray antenna. Designed antenna is capable of independently steering multiple beams in the azimuth and elevation plane by the two dimensional displacement of feed radiators placed in front of the passive meta-surface. The meta-surface acts as an electromagnetic lens. Unit cell of the meta-surface consists of three layers of Rogers 5880 substrate and four layers of etched copper. Unit cell is designed such that the phase of unit cell transmission coefficient is varied from 0° to 360° by changing length of the etched copper pattern. As a proof of concept, meta-surface is designed by using uni-focal phase distribution. Multi-beam steering of 0° to 360° in azimuth plane and 0° to 40° in elevation plane has been achieved. Measured antenna peak gain is 34.2 dBi at 30 GHz. Later on, scan loss was optimized by synthesizing a meta-surface with bi-focal phase distribution. This is a mission enabling technology as the antenna supports seamless hand-off between satellites by forming multiple high gain independently steerable beams. Comparable antennas to the date are low gain, bulky, support limited number of beams, and have limited field of view. To the best of the author’s knowledge, it is first time that high gain multi-beam antenna has been demonstrated by using a passive bi-focal meta-surface for continuous beam steering. Due to absence of active components the designed antenna is low cost and robust. Moreover, the substrate is selected such that the antenna can withstand harsh deep space environment and it can be folded for easy deployment. Due to potentially low fabrication cost and ability to support multiple beams, the proposed antenna is a good candidate for next generation satellite communication and mm-Wave 5G systems.

Optimal design of transmitarray antennas via low-cost surrogate modelling

Over the recent years, reflectarrays and transmitarrays have been drawing a considerable attention due to their attractive features, including a possibility of realizing high gain and pencil-like radiation patterns without the employment of complex feeding networks. Among the two, transmitarrays seem to be superior over reflectarrays in terms of achieving high radiation efficiency without the feed blockage. Notwithstanding, the design process of transmitarrays is more intricate due to the necessity of manipulating both the transmission phase and magnitude of its unit elements. For reliability, the design process has to be conducted at the level of full-wave electromagnetic models, which makes direct optimization prohibitive. The most widely used workaround is to employ surrogate modeling techniques to construct fast representations of the unit elements, yet the initial model setup cost is typically high and includes acquisition of thousands of training data points. In this paper, we propose a novel approach to cost-efficient design of transmitarrays. It is based on artificial-intelligence-enabled data-driven surrogates, which can be constructed using only a few hundreds of training data samples, while exhibiting the predictive power sufficient for reliable design. Our methodology is demonstrated by re-using the presented surrogate for the design of high-performance transmitarrays operating at various frequency ranges of 8–14 GHz, 22–28 GHz, and 28–36 GHz.

Wideband Two-Layer Transmitarray Antenna Based on Non-uniform Layers

Wideband Two-Layer Transmitarray Antenna Based on Non-uniform Layers

Experimental Demonstration of a 43-dBi Gain Transmitarray in PCB Technology for Backhauling in the 300-GHz Band

In this paper, a low-cost transmitarray antenna, fabricated using standard printed circuit board (PCB) technology is reported, with application to point-to-point communications in the 300-GHz band. The proposed structure is vialess and comprises only three metal layers with tailored anisotropic properties in transmission. Based on a previously reported numerical model and design of the unit-cell, a 3-bit 140×140-element transmitarray antenna is optimized and demonstrated. The transmission coefficients of the eight unit-cells are characterized experimentally. They exhibit linear phase responses and high transmissivity in a 100-GHz bandwidth. A peak gain of 43.3 dBi and an aperture efficiency of 39.0% are measured. The prototype performance is comparable to that of state-of-the-art high-gain antennas leveraging on more expensive technologies.

Characteristic Mode Inspired Broadband Circularly Polarized Folded Transmitarray Antenna

The circularly polarized (CP) antennas with high gains have gained growing interest due to their significant advantages, but the existing works usually suffer from narrow bandwidths. In this work, a novel circularly polarized folded transmitarray antenna (CPFTA) inspired by the characteristic mode analysis (CMA) method is proposed to achieve a broadband and high-gain CP radiation. The proposed CPFTA consists of a top-layer multifunctional metasurface (MTS), a bottom-layer polarization conversion metasurface (PCM) integrated with a linearly polarized (LP) microstrip feed source. Enabled by the CMA, the unit cell etched with an asymmetric U-slot of the MTS is optimized to generate two pairs of CP modes to broaden the bandwidth of the CPFTA. Moreover, a modified broadband E-shaped LP microstrip antenna is integrated with the PCM, resulting in a compact profile. A CPFTA prototype is fabricated and characterized to verify the effectiveness of the design. The measured results show that the fabricated antenna could obtain an impedance bandwidth of 31.7%, a 3 dB axial ratio (AR) bandwidth of 36.5%, and a 3 dB gain bandwidth of 30.1% with a peak gain of 22.35 dBic at 9.55 GHz.

Low-Profile Dual-Band Dual-Polarized Transmitarray Antenna Based on Multilayer Frequency Selective Surfaces

Low-Profile Dual-Band Dual-Polarized Transmitarray Antenna Based on Multilayer Frequency Selective Surfaces

Wideband single-feed dual circularly polarized multi-beam transmitarray antenna based on receiver–transmitter metasurface

In this paper, a novel metasurface (MS) as well as a generalized dual-circular-polarized (CP) decoupled modulating method are proposed. The proposed MS can realize high-efficiency dual-spin transmissions with equal-magnitude upon left handed circular polarization (LCP) incidence across 9–12.5 GHz. This MS is constructed based on the receiver–transmitter configuration, and the receiver layer composed of an LCP patch resonator while the transmitter layer is a linearly polarized patch resonator. Rotating the receiver and transmitter patches separately can impose identical and conjugated geometric phase modulations for the dual-CP transmission waves, respectively. Hence, through an elaborate combination of the dual geometric phases, totally decoupled and dispersion-less phase modulations for transmitted dual-spin waves can be obtained. As the proof of its uses in practical applications, we have designed a single-feed dual-CP dual-beam transmitarray antenna (TA) and a dual-CP quad-beam TA. The second TA is also fabricated and tested. The measured results are consistent with the simulated results, showing that the TA achieves peak aperture efficiency of 49% at 9.5 GHz, with 1 dB gain bandwidths (BWs) of the dual-CP quad-beams all larger than 24.5% while 3 dB axial ratio BWs all larger than 54.5%. The proposed wideband and high-gain dual-CP multi-beam TAs may have promising prospects for many applications such as vehicle-satellite communication systems, satellite broadcasting and coverage systems.

A Broadband Double-Layer Transmitarray Antenna Based on Polarization Conversion Elements

A broadband double-layer transmitarray antenna (TA) is proposed in this letter. In order to obtain broadband performance in a double-layer structure, we use a “receiving-transmitting” (RX-TX) structure instead of a double-layer frequency selective surface. The elements of the new TA are composed with metal layers and dielectric substrate. Both the metal layer are connected by a metallized via and etched with orthogonal slots. The RX and TX layers work without interfering while converting the linearly polarized incident wave into orthogonal polarization. Phase compensation can be achieved by changing the direction and length of the microstrip meander ling. Then, a broadband TA is designed. Considering the simplicity of the design, we sequentially selected eight phase states at 45° intervals for phase modulation. The measured maximum antenna gain is 24.5 dBi. The center frequency is 10 GHz. The measured 1-dB and 3-dB gain bandwidth(BW) are 18.7% and 29.4%, respectively. The maximum aperture efficiency (AE) is 51%.

A Wideband Circularly Polarized Magnetoelectric Dipole Transmitarray Antenna Based on Element Rotation Techniques

In this article, a wideband circularly polarized (CP) transmitarray antenna (TA) operating at the X-band is reported. A receive-and-transmit type anisotropic magneto-electric (ME) dipole is proposed as the broadband TA unit cell with low-insertion-loss characteristic. By employing the element rotation methodology, the continuous transmissive phase compensation is achieved, thus producing the high-gain directive radiation. The 16×16-element CP TA implemented using the designed ME-dipole structure not only possesses wide measured 1-dB and 3-dB gain bandwidths of 24.5% (10.75-13.75 GHz) and 33.3% (10-14 GHz), respectively, but also yields a notable 1.5-dB axial ratio (AR) bandwidth of 37.4% (9.25-13.5 GHz). Peak gain of 24.3 dBic and aperture efficiency of 46% are experimentally measured. The proposed CP TA shows attractive advantages including wide bandwidth, high-purity circular polarization and stable gain, which makes it a competitive candidate for many applications including satellite communication (SatCom).