Wave Antenna Array Research Articles

Electromagnetic shielding and multi-beam radiation with high conductivity multilayer graphene film

In the microwave region, graphene material usually has a relatively high resistivity, which limits its application potential in electromagnetic shielding and radiation. Meanwhile, conventional carbon materials are difficult to meet the requirement of electronic devices and electromagnetic shielding in terms of thickness reduction and flexibility. Here, a flexible multilayer graphene film (MGF) with high conductivity and small thickness is achieved by high temperature thermal treatment of GO films and subsequence compression rolling. We experimentally study the EMI shielding performance of the MGF with a thickness of 27 μm, which shows high shielding effectiveness (SE) of 70 dB from 2.6 GHz to 40 GHz. Making use of its high conductivity of 1.13 × 106 S/m and low sheet resistance of 32.7 mΩ/□, a MGF based multi-beam millimeter wave antenna array with average gain of 15.07 dBi and large beam scanning range of 120°is realized for the first time. All the measurements indicate that the flexible, low thickness, low-density and highly conductive multi-layer graphene film have great potential in the application of electromagnetic shielding, electromagnetic conduction and electromagnetic radiation devices.

Novel and active technique for controlling the radiation pattern of the half-width microstrip leaky wave antenna array

A novel, half width–microstrip leaky wave antenna (HW–MLWA) array is presented in this paper. It can electronically control its beam at fixed frequency using a double gap capacitor with diodes and has good impedance matching and very small variation gain while scanning. The control radiation pattern of leaky wave antennas (LWAs) is examined in steps at a certain frequency using binary switches, and a novel HW–MLWA array is proposed. This antenna is mainly composed of two elements of HW–MLWA and seven control unit cells (CUCs). In addition, a reconfigurable CUC is created by combining two triangle patches as double–gap capacitors with two diodes as a switch to connect the patches with a ground plane. The proposed antenna is fabricated and validated. To achieve certain–frequency beam steering, a patch in each CUCs is independently disconnected or connected with the ground plane by using PIN diode switches. When the state of the patch cell is changed, the reactance profile is altered at the free edge of the microstrip that caused the direction of the main beam to change. This proposed antenna prototype can scan the main beam between +22° to +63° at 4.2 GHz, and the antenna has a measured peak gain of 12.72 dBi at 4.2 GHz.

Compact bilayer substrate integrated waveguide leaky wave antenna with dumbbell‐shaped slot based on the TE 20 mode

In this article, a compact dual layer leaky wave antenna array is simulated and constructed using the substrate integrated waveguide (SIW) based on the TE20 mode at the X- and Ku-bands. The proposed antenna is designed by creating dumbbell-shaped slots on the upper layer of the SIW. These slots have increased the antenna bandwidth so that the proposed antenna has a bandwidth of 9.5 to 13.7 GHz and a fractional bandwidth of 36%. In addition, to excite the TE20 mode, an SIW power divider is used in the feeding network of the antenna located in the bottom layer. Moreover, the gain and directivity are other advantages of the proposed antenna so that at 12.5 GHz the antenna peak gain reaches to 15.7 dB. Antenna beam scanning angle is from 5° to 81°. This antenna is simulated and analyzed by the CST Microwave Studio software. The obtained results from the antenna test lab confirm the simulation results.

Electronically controlled radiation pattern leaky wave antenna array for (C band) application

This paper provides an insight of a new, leaky-wave antenna (LWA) array. It holds the ability to digitally steer its beam at a fixed frequency by utilizing only two state of bias voltage. This is done with acceptable impedance matching while scanning and very little gain variation. Investigation is carried out on LWAs’ control radiation pattern in steps at a fixed frequency via PIN diodes switches. This study also presents a novel half-width microstrip LWA (HWMLWA) array. The antenna is made up of the following basic structures: two elements and reconfigurable control cell with each being comprised of two diodes and two triangle patches. A double gap capacitor in each unit cell is independently disconnected or connected via PIN diode switch to achieve fixed-frequency control radiation pattern. The reactance profile at the microstrip’s free edge and thus the main beam direction is changed once the control-cell states are changed. The main beam may be directed by the antenna between 61o and 19o at 4.2 GHz. C band achieved the measured peak gain of the antenna of 15 dBi at 4.2 GHz beam scanning range.

On Unified Vehicular Communications and Radar Sensing in Millimeter-Wave and Low Terahertz Bands

Future smart vehicles will incorporate highdata- rate communications and high-resolution radar sensing capabilities operating in the millimeter- wave and higher frequencies. These two systems are preparing to share and reuse many common functionalities, such as steerable millimeter- wave antenna arrays. Motivated by this growing overlap, which is advanced further by space and cost constraints, the vehicular community is pursuing a vision of unified vehicular communications and radar sensing that represents a major paradigm shift for next-generation connected and self-driving cars. This article outlines a path to materialize this decisive transformation. We begin by reviewing the latest developments in hybrid vehicular communications and radar systems, and then propose a concept of unified channel access over millimeter-wave and higher frequencies. Our supporting system-level performance characterization relies upon real-life measurements and extensive ray-based modeling to confirm the significant improvements brought by our proposal to mitigating the interference and deafness effects. Since our results aim to open the door to unified vehicular communications and radar sensing, we conclude by outlining the potential research directions in this rapidly developing field.

A miniaturized ultra‐high frequency microstrip traveling wave antenna Array for cm‐level two‐dimensional identification and position detection systems

AbstractIn this article, a miniaturized ultra‐high frequency (UHF) microstrip traveling wave antenna (TWA) array for cm‐level 2D identification (ID) and position detection systems is proposed. The proposed miniaturized TWA array with nine reading zones for ID and position detection systems has been reduced in size by utilizing LC‐baluns and a microstrip TWA array. It covers the authorized universal UHF radio frequency ID band (840‐960 MHz), has low insertion loss (0.8 dB), and high isolations between TWAs are ≤30 dB. The sensing precision of the proposed TWA array is approximately 1.5 cm and its physical size is 95 × 95 mm2 (~1/4 λ0 at 915 MHz).

Complex beam steering from substrate integrated waveguide leaky wave antenna array

A wideband single-beam/dual-beam leaky wave antenna (LWA) system based on periodic composite right-left handed substrate integrated waveguide is presented in this article. The proposed array can be a good candidate for tracking applications and intelligent protection systems. The system is contributed by installing in parallel two different antenna structures. The first antenna transmits in the frequency band 6.9-11 GHz where the second antenna radiates in the band 8.9-13.8 GHz, the frequencies of the broadside radiation are allocated at 7.8 and 10.2 GHz for the first and the second LWA, respectively. The results demonstrate the potential of the proposed system to continuously steer a single or a dual beams from −72° to 73°. The antenna system has a flexible beam scanning mechanism, good radiation efficiency, and maximum gain of 15.2 dBi. The simulation and the measurement results match well with the theoretical analysis described in the article.

Compressive Sensing for Millimeter Wave Antenna Array Diagnosis

The radiation pattern of an antenna array depends on the excitation weights and the geometry of the array. Due to wind and atmospheric conditions, outdoor millimeter wave antenna elements are subject to full or partial blockages from a plethora of particles like dirt, salt, ice, and water droplets. Handheld devices are also subject to blockages from random finger placement and/or finger prints. These blockages cause absorption and scattering to the signal incident on the array, modify the array geometry, and distort the far-field radiation pattern of the array. This paper studies the effects of blockages on the far-field radiation pattern of linear arrays and proposes several array diagnosis techniques for millimeter wave antenna arrays. The proposed techniques jointly estimate the locations of the blocked antennas and the induced attenuation and phase-shifts given knowledge of the angles of arrival/departure. Numerical results show that the proposed techniques provide satisfactory results in terms of fault detection with reduced number of measurements (diagnosis time) provided that the number of blockages is small compared to the array size.

Planar High-efficiency Antenna Array Using New Printed Ridge Gap Waveguide Technology

High-efficiency millimeter wave antenna array is proposed. A cooperate feeding network is designed using the new printed ridge gap waveguide technology, which is self-packaged with low loss. The feeding network is designed to couple to narrow slots arranged in a planar array that is coupled to printed broadband magnetoelectric (ME) dipoles. An array of $4 \times 4$ ME dipoles is designed. The simulated results are verified with measurements. The measured reflection coefficient is less than −10 dB over 16.5% bandwidth (28.8–34 GHz). The measured antenna gain is higher than 19 dBi, and the cross polarization measured gain is around −35 dB within the main beam. Furthermore, the measured total radiation efficiency is 70%, and the measured aperture efficiency corresponds to 90% at 30.2 GHz.

A Submillimeter-Wave Near-Field Measurement Setup for On-Wafer Pattern and Gain Characterization of Antennas and Arrays

This paper presents a measurement system for on-wafer characterization of antennas operating in the high millimeter wave (MMW) to sub-MMW bands. Most existing antenna measurement systems at these frequencies require complex custom-made structures, which are costly and hard to set up. To address this problem, a simple and yet effective near-field antenna measurement setup consisting of a vector network analyzer (VNA) with proper frequency extenders, a probe station, an on-wafer waveguide probe, and a precision XY-positioner is considered. The waveguide probe attached from one end to a frequency extender of VNA is used to feed the micromachined waveguide port of an on-wafer antenna. A second waveguide probe, connected to the other frequency extender of VNA, is moved over the antenna in the near-field region using the precision XY-positioner. The absolute gain measurement is accomplished by measuring and comparing the near field of a standard gain horn antenna against that of the antenna under test. To validate the performance of the setup, radiation characteristics of a beam-steering traveling wave array antenna and a standard pyramidal horn antenna are measured over 220–325 GHz band and good agreement between the measured and simulated radiation patterns and gains is shown.

Compact 4G MIMO antenna integrated with a 5G array for current and future mobile handsets

A novel integrated antenna solution for wireless handheld devices is proposed for the existing 4G standards and upcoming 5G systems for broadband, high data rate communications. The complete antenna system is a unique combination of a multiple-input-multiple-output (MIMO) antenna system at microwave frequencies and a millimetre (mm)-wave antenna array. The MIMO antenna system consists of two reactive loaded monopoles while the mm-wave array consists of a planar 2 by four slot antennas. The integrated antenna system covers the frequency bands from 1870 to 2530 MHz for 4G standards along with the upcoming 5G mm-wave band at 28 GHz. In addition, the integrated antenna system is planar and is designed for typical smart phone devices with a standard 60 mm by 100 mm by 0.965 mm back plane. Excellent field correlation values were obtained across the 4G band while realised peak gain values of 4 and 8 dBi were, respectively, measured for the MIMO and mm-wave antenna arrays. The proposed antenna design may also be useful for other compact implementations that support 4G and 5G communications.

Novel Method for Optimal Synthesis of 5G Millimeter Wave Linear Antenna Array

We will propose a useful method for 5G mm wave antenna array synthesis, based on Genetic Algorithm for the synthesis of linear array with nonuniform interelement spacing. Our design method was used to obtain the optimal position of the elements in order to get the minimum side lobe level and nulls in desired directions. The simulation results verify that proposed method outperforms the previously published methods in terms of suppression side lobe level while maintaining nulls in specified directions. The flexibility of proposed algorithm shows good potential for the antenna array synthesis.

CPW-Fed Printed Antenna Array With Conical Beam

A printed antenna array with conical beam is presented. Coplanar waveguide (CPW) is used to feed the antenna. Loop slots with finite width of ground plane, which play the role of radiating elements are arranged collinearly to form a traveling wave antenna array. The widths of the loop slots are adjusted to achieve low sidelobe performance. The design procedures are proposed and a 16-element array with beam-pointing angle of 77° is fabricated and measured to verify the design. The measured 15-dB return loss bandwidth is 11.4% at central frequency of 10.5 GHz. The measured gain and the sidelobe level are 10.3 dBi and $-20\;\text{dB}$ , respectively. The agreement between the measured and the simulated results is acceptable.

All-Metal Antenna Array Based on Microstrip Line Structure

In this communication, an all-metal standing wave antenna array is proposed based on the microstrip transmission line. By alternatively blocking the microstrip line every half wavelength, the symmetrical equivalent magnetic currents are broken for effectively radiating. By properly tuning the blocking positions along the microstrip line, a broadside pattern is achieved with high gain. The proposed antenna is scalable along one direction to a certain level to acquire the directivity as high as about 15 dBi. More importantly, the proposed antenna array has the potential to be built only by metal without any dielectrics. The all-metal structure has the merits of being low-cost, light weight, easily fabricated, and having no dielectric losses. Based on this idea, a five-segment linear array with a center feed is designed and tested. The measured bandwidth is from 7.83 to 8.81 GHz (980 MHz, 11.78%), and the measured gain is ranging from 9.1 to 12.47 dBi.

Computer Automated Design of an Irregular Slotted Waveguide Array for Ku-Band

A computer automated design methodology to synthesize a progressive wave array antenna is presented. The proposed method is based on the generalized-scattering matrix and spherical wave expansion analysis of the array. Mutual coupling effects between radiating elements are inherently considered in the design process. A linearly polarized 24-element irregular slotted array antenna at Ku-band is presented to describe the proposed computer automated design methodology. A prototype has been manufactured to experimentally validate the antenna performance. At the design frequency (17 GHz), 15.9 dB realized gain and 97% efficiency (excluding aluminum losses) values are achieved. Although the array is designed at a single frequency, it shows an overall experimental 7% usable bandwidth.

Periodic Collinear-Slotted Leaky Wave Antenna With Open Stopband Elimination

A low cross-polarization periodic-slotted ridged substrate-integrated waveguide (RSIW) leaky wave antenna (LWA) array is presented. Parametric constraints of the structure were investigated to realize a periodic leaky wave antenna (PLWA) with the ability of scanning from backward endfire into the forward quadrant. An appropriate multimode transverse equivalent network (TEN) is presented for the proposed antenna and values of leakage rate and phase constant for different parameters of the structure were extracted using the transverse resonance technique (TRT). The obtained results were compared to those achieved from HFSS software simulations. The open stopband in the broadside is eliminated using certain dimensions for the structure. By simultaneously manipulating a number of parameters, a variable {\alpha} and constant \b{eta} are resulted so that the desired sidelobe level (SLL) can be realized. The proposed structure was simulated and then manufactured. Simulation results show good agreement with measurement results.

Design and Operation of an Edge-Wall Slotted Waveguide Array Antenna with Ultralow Side Lobes for Application of Off-Shore Radar

This paper presents the design, fabrication, and operation of an edge-wall slotted waveguide array antenna with metal flare for the generation of ultralow side lobes fan-beam radiation. The single traveling wave array antenna consists of 71 radiating elements. The radiation pattern at the operating band was designed utilizing the Taylor's aperture distribution to achieve an ultralow side lobe level (SLL) of -33 dB. The mathematical relationship between the slot characteristics and the conductance is evaluated by the least squared quadratic curve fitting procedure. Finite element method software is used to analyze the various antenna characteristics of the radiating slots, including return loss, insertion loss, and radiation patterns. The array antenna was fabricated and the performance characteristics of the antenna were measured in an antenna near-field measurement chamber. The well match of the measured and simulated results indicated the excellent design of the array antenna with ultralow side lobes. Finally, the unit was fitted onto a search radar system and an experimental test on the radar returns on Keelung Islet was carried out. The clear radar signals of the islet showed the well design of the unit.

Radiation Pattern Optimization by Loaded Impedance in the Base of Passive Element

Radiation Pattern Optimization by Loaded Impedance in the Base of Passive ElementThis article deals with optimizing the radiation pattern by using two vertical middle wave antenna arrays. Optimization is achieved by adding an appropriate impedance into the base of the passive antenna radiator. The proposed solution deals with finding the best value of the loaded impedance. The final result is to achieve the most effective shape of the radiation pattern. The proposed method was finally approved by measurement on a real middle wave antenna array.

A Substrate Integrated Waveguide Circular Polarized Slot Radiator and Its Linear Array

A top-wall substrate integrated waveguide (SIW) slot radiator for generating circular polarized (CP) field is proposed and characterized in this letter. The reflection of the slot radiator is extremely weak, which simplifies the linear traveling wave array design. Based on such a structure, a 16-element CP SIW traveling wave antenna array is designed, fabricated, and measured at 16 GHz. A -23 dB side lobe level (SLL) with an axial ratio (AR) of 1.95 dB is experimentally achieved. The size of the proposed SIW CP linear array antenna is 285 mm times 22 mm. The measured gain is 18.9 dB, and the usable bandwidth is 2.5%.

A Fixed-Frequency Beam-Scanning Microstrip Leaky Wave Antenna Array

A novel two-element fixed-frequency beam-scanning microstrip leaky wave antenna (MLWA) array is presented in this letter. By controlling the phase shifter, the mainlobe of the microstrip leaky wave antenna array is steered at the fixed frequency. The measured H-plane radiation patterns and the simulated results show that the mainlobe can be scanned from 41deg to 62deg continuously when the operating frequency fixes at 7 GHz. This new MLWA array can be used as a collision avoidance system or automotive radar system.