Beam-scanning Leaky-wave Antenna Research Articles

Circularly polarized beam-scanning leaky wave antenna based on a slow-wave substrate integrated waveguide

A circularly polarized (CP) beam-scanning leaky wave antenna (LWA) based on a slow-wave substrate integrated waveguide (SW-SIW) is presented in this paper. The SW effect is realized by introducing a spoof surface plasmon polariton (SSPP), excited by periodic etched 45° tilted slots on the top metallic layer of an SIW. With extra delta modulation, the electromagnetic waves radiate through the etched slots and scan continuously from a backward to forward direction as the frequency changes. Taking advantage of the tilted slots and relative displacement between the upper and lower slots, the direction of the electric field of the radiated waves and phase difference between them are adjustable, making a CP characteristic available. Both the simulated and measured results show the proposed LWA exhibits good performance. The total scanning angle reaches 70°, and the average gain is 8.9 dBi from 9.5 GHz to 11.7 GHz. The CP characteristic is verified through the axial ratio of less than 3 during the operating frequency range. A simple structure, compact size, and good performance make the proposed design promising for a compact wireless communication system.

A Ka-band one-dimensional beam scanning leaky-wave antenna based on liquid crystal

Fixed frequency beam-scanning leaky-wave antennas have been a focus of attention for many scholars in recent years, and numerous related results have been obtained. However, these antennas suffer from several issues such as small beam-scanning range, low gain, and unsatisfactory impedance matching. To address these problems, this paper proposes a microstrip line (ML) antenna unit based on liquid crystal (LC) materials etched Complementary Split Ring Resonator (CSRR). In a first-of-its-kind approach, the substrate integrated waveguide (SIW) structure and the ML transmission structure are combined to present the SIW-ML transmission structure. The antenna operates in the Ka-band with excellent resonance characteristics at 34.7 GHz, and the S11 parameters are below − 13 dB in the frequency range of 30–40 GHz, indicating outstanding impedance matching. By arranging 56 antenna units, a periodic leaky-wave antenna is created, enabling fixed-frequency beam-scanning at 34.7 GHz. Experimental results show that the antenna can achieve scanning of angles between − 53° and + 60° with a gain of up to 12.63 dB. Once single-beam scanning is achieved, a method combining LC and discrete amplitude weighting technique, as well as multi-beam theory, is proposed for multi-beam study. Experimental results reveal that the designed 56-unit beam-scanning antenna can effectively realize beam scanning in two directions.

A 2-D Circularly Polarized Fixed-Frequency Beam-Scanning Leaky-Wave Antenna for Millimeter-Wave Satellite Communication

A 2-D Circularly Polarized Fixed-Frequency Beam-Scanning Leaky-Wave Antenna for Millimeter-Wave Satellite Communication

Continuously Beam-Scanning Leaky-Wave Antenna Based on Impedance-Matched Spoof Surface Plasmon Polaritons

A leaky-wave antenna (LWA) based on impedance-matched spoof surface plasmon polaritons (SSPPs) is proposed in this paper. Periodic perturbations in the form of impedance stepping SSPPs is introduced to break the stable transmission condition of SSPPs, resulting in the energy radiation and the angle of the main radiation beam changes from backward to forward quadrant as the frequency changes. Open-stop band (OSB) existing in normal periodic LWA is suppressed by properly designing the matched structure between the impedance stepping SSPPs. A prototype of the proposed LWA is simulated, fabricated, and measured. The measured results are in reasonable agreement with the simulated results. Simulated and measured results indicate that the proposed LWA operates with a continuous beam scanning range in each upper and lower half-space, as well as an average gain level of 9.86 dBi. The proposed antenna can be easily integrated and is promising in planar wireless communication systems.

Beam scanning leaky wave antenna based on liquid crystals with gesture-controlled system

ABSTRACT Controlling objects with body language is an extremely interesting ability for human beings. Recognizing different gestures is an effective way to collect valuable information, which is used to switch the radiation characteristic of beam scanning antennas. However, most existing beam scanning antennas are wire-connected and manually controlled by users. Thereby, a novel framework of gesture-controlled antennas is proposed in this paper. Rather than DC voltages supplied by powers or AC voltages supplied by signal generators, the beam scanning antenna can be effectively controlled by different gesture commands collected in real time from the user. On this basis, considering the advantages of the low cost and wide frequency band of liquid crystal (LC) materials, a LC-based fixed-frequency beam scanning leaky wave antenna (LWA) with gesture-controlled systems is demonstrated as one example. Different gestures can be recognised as controlled information to supply corresponding output signals by field programmable gate arrays (FPGAs) for the LC-based LWA. Based on the proposed framework, a verification system is tested, which demonstrates that the radiation characteristic can be effectively controlled by the user’s gesture. This work supplies a novel way for intelligent beam scanning antennas with potential applications in the internet of things (IoT), satellite and 5 G/6 G communications.

Wide-Angle Beam-Scanning Leaky-Wave Antenna Array Based on Hole Array SSPPs

In this letter, a leaky-wave antenna (LWA) array based on hole array spoof surface plasmon polaritons (SSPPs) is proposed, which can realize wide frequency beam scanning angle. By etching periodic hole arrays on the upper metal of the defective ground structure, the SSPP structure is formed and the frequency scanning beam is generated by using its higher-order radiation mode characteristics. The radiation mechanisms of the design are explained by using the dispersion relationship, electric field distributions, and space harmonics. The LWA array is fed by a 1 to 4 power divider and achieves good impedance matching within 6-16 GHz bandwidth. The average peak gain value of the proposed LWA antenna array is about 16.86 dBi and the frequency beam scanning range is 91°. The antenna array has the characteristics of easy fabrication, low cost, and high gain performance, which provides a new design concept for wide-scanning-angle LWA Array and can meet the demand of high gain requirements in radar and other related fields.

A Circular-Polarization-Reconfigurable Holographic Leaky-Wave Antenna With Fixed-Frequency Beam-Scanning Property

A fixed-frequency beam-scanning leaky-wave antenna (LWA) with circular-polarization (CP) reconfigurable property operating in Ka band is developed in this letter. A groove gap waveguide (GGW) structure is adopted for feeding and transmission, and 64 CP patches are excited through the cross-shaped slots etched over the GGW. By switching the conditions between “ON” and “OFF” of the PIN diodes, these exciting slots can act as either transverse slots or longitudinal slots, and hence to realize the transition between left-handed circular polarization (LHCP) and right-handed circular polarization (RHCP). Meanwhile, the fixed-frequency beam-scanning characteristic is achieved by manipulating the hologram, which is controlled by the activation states of diodes. Finally, the presented fabrication is taken into experiment to verify its performance, and an agreement can be observed in the simulated and experimental results. The eventual peak gains reach 13.4 dBic in the LHCP state and 12.1 dBic in the RHCP state, respectively. In addition, a beam-scanning range up to 100° between -50° and 50°is realized with desirable CP reconfigurable performance between LHCP and RHCP.

Dual-Polarized Multi-Beam Fixed-Frequency Beam Scanning Leaky-Wave Antenna.

A fixed-frequency beam-scanning leaky-wave antenna (LWA) array with three switchable dual-polarized beams is proposed and experimentally demonstrated. The proposed LWA array consists of three groups of spoof surface plasmon polaritons (SPPs) LWAs with different modulation period lengths and a control circuit. Each group of SPPs LWAs can independently control the beam steering at a fixed frequency by loading varactor diodes. The proposed antenna can be configured in both multi-beam mode and single-beam mode, where the multi-beam mode with optional two or three dual-polarized beams. The beam width can be flexibly adjusted from narrow to wide by switching between multi-beam and single-beam states. The prototype of the proposed LWA array is fabricated and measured, and both simulation and experimental results show that the antenna can accomplish a fixed frequency beam scanning at an operating frequency of 3.3 to 3.8 GHz with a maximum scanning range of about 35° in multi-beam mode and about 55° in single-beam mode. It could be a promising candidate for application in the space-air-ground integrated network scenario in satellite communication and future 6G communication systems.

Multi-Layer Beam Scanning Leaky Wave Antenna for Remote Vital Signs Detection at 60 GHz.

A multi-layer beam-scanning leaky wave antenna (LWA) for remote vital sign monitoring (RVSM) at 60 GHz using a single-tone continuous-wave (CW) Doppler radar has been developed in a typical dynamic environment. The antenna's components are: a partially reflecting surface (PRS), high-impedance surfaces (HISs), and a plain dielectric slab. A dipole antenna works as a source together with these elements to produce a gain of 24 dBi, a frequency beam scanning range of 30°, and precise remote vital sign monitoring (RVSM) up to 4 m across the operating frequency range (58-66 GHz). The antenna requirements for the DR are summarised in a typical dynamic scenario where a patient is to have continuous monitoring remotely, while sleeping. During the continuous health monitoring process, the patient has the freedom to move up to one meter away from the fixed sensor position.The proposed multi-layer LWA system was placed at a distance of 2 m and 4 m from the test subject to confirm the suitability of the developed antenna for dynamic RVSM applications. A proper setting of the operating frequency range (58 to 66 GHz) enabled the detection of both heart beats and respiration rates of the subject within a 30° angular range.

Ka-band beam-scanning leaky-wave antenna fed by reconfigurable spoof surface plasmon polaritons.

A leaky-wave antenna (LWA) based on reconfigurable spoof surface plasmon polaritons (SSPP) is proposed for beam scanning in the Ka band, which consists of a reconfigurable SSPP waveguide and a periodic array of metal rectangular split rings. Both numerical simulations and experimental measurements show that the reconfigurable SSPP-fed LWA has good performance in the frequency range from 25 to 30 GHz. Specifically, as the bias voltage changes from 0 to 15 V, we can achieve the maximum sweep range of 24° at a single frequency and 59° at multiple frequency points, respectively. Owing to the wide-angle beam-steering feature, as well as the field confinement and wavelength compression properties derived from the SSPP architecture, the proposed SSPP-fed LWA possesses great potential applications in the compact and miniaturized devices and systems of the Ka band.

A Fixed-Frequency Beam-Scanning Leaky-Wave Antenna Using Phase and Amplitude Control for Millimeter-Wave Applications

A new type of fixed-frequency beam-scanning leaky-wave antenna (LWA) in Ka millimeter-waveband is developed in this article, based on dual control of phase and amplitude. The antenna consists of a groove gap waveguide (GGW) and 80 perturbation units. Each unit contains one patch and a pair of H-shaped slots. By controlling the state of a slot with p-i-n diodes, the phase of the radiated field from each unit can be switched between two opposite phases, called “1” state and “−1” state, while the magnitude of the radiated field remains unchanged. In addition, the radiation strength of each unit can be also turned off to provide amplitude control. The main principle for beam scanning is based on the phase compensation to the perturbation units on the surface of the LWA, combined with 1-bit amplitude control to achieve lower sidelobe levels, so the principle is different from that of the existing fixed-frequency beam-scanning LWAs. The entire antenna structure relies on GGW transmission to reduce dielectric loss in millimeter-waveband, and shows good characteristics of scanning angle and realized gain. In the measurement, a high peak gain of 16.8 dBi and a large beam-scanning range over 110° are achieved.

DOA Estimation of Coherent Signals Based on EPUMA Method With Frequency Beam Scanning Leaky-Wave Antennas

DOA Estimation of Coherent Signals Based on EPUMA Method With Frequency Beam Scanning Leaky-Wave Antennas

A Quad-Polarization Reconfigurable Fixed-Frequency Beam-Scanning Leaky-Wave Antenna Based on the Holographic Method for Millimeter-Wave Application

A quad-polarization reconfigurable fixed-frequency beam-scanning leaky-wave antenna (LWA) operating at millimeter-wave Ka-band is presented in this article. A low-loss groove gap waveguide (GGW) structure is employed for low-loss transmission and feeding, above which there locates a metal-covered superstrate. Two rows of inclined slots etched on the metal cover in a staggered arrangement operate as the radiated sources. A modified holographic method is presented, and the hologram can be manipulated by switching the states between “ON” and “OFF” of the p-i-n diodes, and hence the fixed-frequency beam-scanning property with polarization agility of four different polarization states can be realized, including horizontal polarization (HP), vertical polarization (VP), left-handed circular polarization (LHCP), and right-handed circular polarization (RHCP). Besides, measured results of the fabricated antenna are given to verify its performance. The measured peak gains at 30 GHz reach 11.3 dBi in the HP state, 13.0 dBi in the VP state, 11.5 dBic in the LHCP state, and 11.8 dBic in the RHCP state, respectively, with a beam-scanning range of 100° (from −50° to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mathrm{50}^{\circ }$ </tex-math></inline-formula> ), showing good agreement with the simulated results.

Wide-Angle Spoof Surface Plasmon Polariton Leaky-Wave Antenna Exploiting Prefractal Structures With Backfire to Nearly Endfire Scanning

This letter presents a single-layer, wide-angle, low-cost frequency beam scanning leaky-wave antenna (LWA) based on spoof surface plasmon polaritons (SSPPs). Here, two rows of Sierpinski prefractal parasitic patches are placed near an ultrathin planar SSPP waveguide, which can achieve continuous backfire to nearly endfire beam scanning with increasing frequency. The overall width of the proposed antenna is only 0.75 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\lambda _{\text{0}}$</tex-math></inline-formula> (with <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\lambda _{\text{0}}$</tex-math></inline-formula> being the wavelength of the lowest operating frequency). This SSPP LWA provides high-performance backfire and broadside radiations due to applying prefractal units. Simulated results show that the proposed SSPP LWA achieves a wide scanning range from −90 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^{\circ }$</tex-math></inline-formula> to +58 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^{\circ }$</tex-math></inline-formula> within the frequency range of 3–8 GHz. The average gain and radiation efficiency of the antenna are 10.9 dBi and 88%, respectively. An antenna prototype is fabricated and measured. The measured results agree reasonably well with the simulated ones.

A TE₀₁-Mode Groove-Gap-Waveguide-Based Wideband Fixed-Frequency Beam-Scanning Leaky-Wave Antenna for Millimeter-Wave Applications

A wideband fixed-frequency beam-scanning leaky-wave antenna (LWA) operating at the millimeter-waveband is presented in this article. A groove gap waveguide (GGW) supporting base is introduced as a transmission structure of the antenna with a TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">01</sub> -mode excitation, and two rows of longitudinal slots etched on top of the superstrate act as the radiating structures. Two rows of PIN diodes are soldered below the longitudinal slots, so that the long slots can be cut into a group of short slots. By controlling the PIN diodes, the working states of the slots can be switched between “ON” and “OFF.” Then, by selecting proper activation states, the fixed-frequency beam scanning can be obtained. In addition, the developed antenna is verified in practical fabrication and experiment. The experimental results have good agreements with that in simulations. The measured peak gain reaches at 16.8 dBi, and the beam-scanning range more than 70° from 23 to 29 GHz is realized.

Dual-band composite right/left-handed metamaterial lines with dynamically controllable nonreciprocal phase shift proportional to operating frequency

Abstract Dual-band composite right/left-handed transmission lines with the nonreciprocal phase shift approximately proportional to the operating frequency are proposed and demonstrated by using normally magnetized ferrite microstrip lines. The nonreciprocal phase shift can be dynamically controlled by changing the externally applied dc magnetic field. Dynamic change in the nonreciprocal phase gradient along the line enables us to realize dual-band and unidirectional beam-scanning leaky-wave antennas without suffering from frequency-dependent change in the beam direction. A prototype nonreciprocal metamaterial line using polycrystalline yttrium iron garnet was fabricated and measured for verification of our basic concept.

Ultrawide-Angle and High-Scanning-Rate Leaky Wave Antenna Based on Spoof Surface Plasmon Polaritons

An ultrawide-angle frequency beam scanning leaky-wave antenna (LWA) with a high scanning rate based on spoof surface plasmon polaritons (SSPPs) waveguide is proposed in this communication. A row of elliptical patches is placed periodically near the SSPPs waveguide, which can shift the fundamental mode of SSPPs waveguide to the fast-wave region and radiate electromagnetic (EM) waves. The simulated results show that the proposed LWA achieves an ultrawide scanning angle range of 172° over a narrow operation bandwidth of 9.8–12.28 GHz, which implies a high scanning rate. The simulated average gain of the proposed LWA is 10.13 dBi and its average total efficiency is 75.35%. The proposed LWA is fabricated and measured. The measured scanning angle range is 167° in the frequency band of 9.9–12.25 GHz, and the measured average gain is 9.73 dBi. Good agreements between the simulated and measured results are obtained, validating the proposed design.

Two-Degree-of-Freedom Control of Field Distribution on Nonreciprocal Metamaterial-Line Resonators and Its Applications to Polarization-Plane-Rotation and Beam- Scanning Leaky-Wave Antennas

Two-degree-of-freedom control of field distribution on the pseudotraveling wave resonator using nonreciprocal metamaterial lines is demonstrated for the first time. Dynamic control of current distribution on the resonator is given based on circuit theory. We employed a normally magnetized ferrite microstrip line-based composite right-/left-handed (CRLH) transmission line as a metamaterial with variable phase-shifting nonreciprocity. Numerical simulation results show that the phase gradient of the fields along the resonator is controlled by the applied dc magnetic field to the ferrite. By changing the reflection coefficients of two reflectors inserted at both ends of the CRLH line section, current distribution along series and shunt branches of the unit cell is continuously and drastically changed under the resonance. The variable field distribution was implemented to polarization-plane-rotation and beam-scanning leaky-wave antennas. The experimental demonstration verifies our basic concept and shows the performance of the prototype antenna with a beam scanning angle of 20° and a continuous rotation angle of polarization plane by ±70° at the fixed frequency.

A compact wide-angle frequency beam-scanning antenna using modulated composite waveguide based on half-mode substrate integrated waveguide and spoof surface plasmon polariton structure

In this paper, we present a novel frequency beam-scanning leaky-wave antenna (LWA) based on a composite half-mode substrate integrated waveguide/spoof surface plasmon polariton (HMSIW/SSPP) waveguide. The new composite HMSIW/SSPP waveguide is accomplished by embedding periodical symmetric subwavelength grooves on both copper surfaces of the HMSIW, which owns flexible transmission characteristics attributed to its features from both HMSIW and SSPP. The conversion of propagating slow-wave mode to radiation mode is devised by a double-sided symmetric sinusoidal modulation method with a π/2 displacement between the top- and bottom-surface. This double-sided modulation method not only offers a compact structure but also effectively eliminates the open stopband. A prototype of the proposed antenna is fabricated and measured to verify the predicted performance from simulation. Experimental results show that the proposed antenna achieves a continuous wide scanning range of 125° from backward to forward for lateral unidirectional radiation with an average peak gain level of 9.1 dBi from 6.3 to 9.7 GHz. And the compact antenna volume of 0.40 × 8.0 × 0.013 λ03 offers a well scanning rate (36.8°/GHz) and a very high gain value per unit volume (219 dBi/λ03).

Dual-polarized Fixed-frequency Beam Scanning Leaky-wave Antenna for 5G Communication

A low profile and dual-polarized fixed-frequency beam scanning leaky wave antenna for 5G communication is presented, which is based on a corrugated microstrip line (CML) called spoof surface plasmons transmission line. The antenna radiates horizontally polarized electromagnetic wave and vertically polarized electromagnetic wave using two different periodic antennas elements. The fabricated antenna is measured and the results show that the operating frequency of the antenna is 3.4-3.7 GHz. The measured main beam angle scans from -9° to -30°. The measured gain is from 8.3 dB to 9.7 dB over the working band.