Periodic Leaky-wave Antenna Research Articles

Compact Slow-Wave Half-Mode SIW Periodic Leaky-Wave Antenna With Continuous Beam Scanning and High Gain

Compact Slow-Wave Half-Mode SIW Periodic Leaky-Wave Antenna With Continuous Beam Scanning and High Gain

Integrated high gain linear leaky wave antenna

Formulation of the problem. In the microwave range, the implementation of radar systems for spatial surveillance, remote sensing and information transmission systems requires relatively simple and reliable low-profile antennas that have a narrow radiation pattern in one of the planes and a high gain. Purpose. Demonstrate the feasibility and efficiency of implementing a high-gain linear antenna based on a periodic leaky wave antenna with series feeding of an integrated aperture. Results. The possibility of effective implementation of an antenna system with a high gain based on a linear periodic leaky wave antenna in the range of 9.2-9.5 GHz is shown. The radiating aperture of the antenna contains a flat dielectric waveguide integrated with a metal periodic grating with rectangular grooves. The values of the geometric parameters of the emitting aperture are indicated. The results of mathematical modeling using an original 2D computational algorithm and full-wave 3D electromagnetic modeling are presented, confirming the effectiveness of the antenna design with the stated geometric parameters. Practical significance. The developed integrated periodic leaky wave antenna of the microwave range can be used to increase the azimuth resolution and range of radar systems, increase the energy potential of information transmission systems without increasing the transmitter power.

Leaky wave antenna loaded complementary elements with dual-stopband suppression

In this paper, a periodic leaky wave antenna (PLWA) using complementary elements is proposed. The complementary elements of the transverse slot (horizontal magnetic current) and the monopole pairs (vertical electric current) in the substrate integrated waveguide (SIW) is employed as the radiation element, which can simultaneously suppress closed stopband β 0 p = π and open stopband (OSB) β −1 p = 0 to enhance the forward scanning of the LWA. Additionally, the gain and cross-polarization of the element are improved due to the loading of the monopole pairs. The LWA achieves forward and backward scanning from −73° to 10° when operating at the n = −1 spatial harmonic (SH), with corresponding gains of 11.5 to 15.4 dBi. When operating at the n = 0 SH, it achieves forward scanning from 58° to 72°, with corresponding gains of 5.2 to 7.5 dBi. Moreovere, due to the element and its symmetrical structure, the cross-polarization within the entire operating frequency range is less than −35 dB. The design concept is validated through processed, fabricated, and tested.

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.

Design of Leaky Wave Antenna for V2V Communications

In this article, a low-profile, microstrip-based, periodic leaky wave antenna has been proposed for vehicle-to-vehicle (V2V) communications. The leaky-wave structure, loaded periodically with stepped impedance resonator stubs operates in the 5.4–6.2 GHz frequency band, which includes the WAVE (Wireless Access in Vehicular Environments) band (5.85–5.925 GHz) required for automated vehicular communications. The S11 obtained in the spectrum is below −12.68 dB. While the majority of the antennas designed for V2V communications produced omnidirectional patterns, the structure proposed in this work yields a directional pattern, preventing unnecessary outages of signals. The periodic structure gives an added advantage of beam scanning, resulting in a wider, yet directive coverage in the desired frequency band. A backward beam scan from −13˚ to −31˚ is obtained in the frequency range of 5.4–6.2 GHz with a gain variation of around ±0.6 dB only.

A Single-Layer Periodic Leaky-Wave Antenna With Full-Space Scanning Capability

A Single-Layer Periodic Leaky-Wave Antenna With Full-Space Scanning Capability

High Endfire Gain Dielectric Image Line Based Periodic Leaky-wave Antenna with Planar Feeding

High Endfire Gain Dielectric Image Line Based Periodic Leaky-wave Antenna with Planar Feeding

An Endfire Periodic Leaky Wave Antenna With Wideband and High-Gain Capability by Manipulating Its Higher-Order Space Harmonics

An Endfire Periodic Leaky Wave Antenna With Wideband and High-Gain Capability by Manipulating Its Higher-Order Space Harmonics

Tunable Multibeam Periodic Leaky-Wave Antenna Based on Radiation of Multiple Space Harmonics

This letter proposes a tunable multi-beam periodic leaky-wave antenna (LWA) based on radiation of multiple space harmonics. The LWA is composed of a microstrip transmission line and a set of stubs. When the main transmission line is loaded with one / two / multiple groups of periodic stubs, one / two / multiple <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$n = - 1$</tex-math></inline-formula> space harmonics that are in the radiation region can be obtained, which are superpositioned to generate one / two / multiple beams. By adjusting the connections between the stubs and the line with switch diodes, the number of beams and the radiation directions can be reconfigured at a fixed frequency. The working mechanism of the tunable multi-beam antenna is investigated. A prototype of tunable dual-beam LWA is fabricated and measured. The measurement results show that two beams can be generated and can be reconfigured independently at a fixed frequency, with maximum gains of 7.93 dBi and 5.48 dBi, respectively.

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.

Simple method to suppress n = −2 harmonic for periodic leaky-wave antennas with open-stopband suppression

Periodic leaky-wave antennas (PLWAs) suffer two main issues limiting their scanning ability. The first one is n= −2 spatial harmonic radiation, generating high grating-lobe levels. In this paper, a simple technique by introducing glide-symmetry structure to the PLWA is analysed and used to reduce n = −2 space harmonic level and enhance n = −1 harmonic radiation, subsequently. The other issue is open-stopband (OSB), preventing PLWAs from scanning through broadside. By analysing the ABCD matrix of the cascaded equivalent circuit for the unit cell, a conjugate match condition to counteract the susceptance of the radiation element to suppress the OSB is obtained, which is simple without extracting any parameters. A half-mode substrate integrated waveguide-based prototype is designed and manufactured to demonstrate the proposed methods. The measured results show that the proposed antenna achieves gain fluctuation lower than 1 dB and sidelobe level less than −12 dB, indicating OSB and n = −2 harmonic suppression well, which demonstrates the validity of the proposed method.

A 220 GHz to 325 GHz Grounded Coplanar Waveguide Based Periodic Leaky-Wave Beam-Steering Antenna in Indium Phosphide Process

This paper presents a novel periodic grounded coplanar waveguide (GCPW) leaky-wave antenna implemented in an Indium Phosphide (InP) process. The antenna is designed to operate in the 220 GHz–325 GHz frequency range, with the goal of integrating it with an InP uni-traveling-carrier photodiode to realize a wireless transmitter module. Future wireless communication systems must deliver a high data rate to multiple users in different locations. Therefore, wireless transmitters need to have a broadband nature, high gain, and beam-steering capability. Leaky-wave antennas offer a simple and cost-effective way to achieve beam-steering by sweeping frequency in the THz range. In this paper, the first periodic GCPW leaky-wave antenna in the 220 GHz–325 GHz frequency range is demonstrated. The antenna design is based on a novel GCPW leaky-wave unit cell (UC) that incorporates mirrored L-slots in the lateral ground planes. These mirrored L-slots effectively mitigate the open stopband phenomenon of a periodic leaky-wave antenna. The leakage rate, phase constant, and Bloch impedance of the novel GCPW leaky-wave UC are analyzed using Floquet’s theory. After optimizing the UC, a periodic GCPW leaky-wave antenna is constructed by cascading 16 UCs. Electromagnetic simulation results of the leaky-wave antenna are compared with an ideal model derived from a single UC. The two design approaches show excellent agreement in terms of their reflection coefficient and beam-steering range. Therefore, the ideal model presented in this paper demonstrates, for the first time, a rapid method for developing periodic leaky-wave antennas. To validate the simulation results, probe-based antenna measurements are conducted, showing close agreement in terms of the reflection coefficient, peak antenna gain, beam-steering angle, and far-field radiation patterns. The periodic GCPW leaky-wave antenna presented in this paper exhibits a high gain of up to 13.5 dBi and a wide beam-steering range from −60° to 35° over the 220 GHz–325 GHz frequency range.

A Wideband Circularly Polarized Periodic Leaky-Wave Antenna Using a Novel Unit Cell With X-Shaped Slot

A wideband circularly polarized periodic leaky-wave antenna (PLWA) using a novel unit-cell with X-shaped slot is proposed. The X-shaped slot is fed by a 50 Ω microstrip line with an X-shaped stub closely on top of it. Furthermore, an equivalent circuit of the proposed unit-cell is established and verified. Approaches are introduced to enhance the impedance and CP bandwidths, which utilize a complementary X-shaped stub and displace one arm of it from the middle to another layer. A 1 × 16 PLWA is constructed with good CP performance. The open-stopband (OSB) is suppressed by using trapezoidal arms of the slot and stub and the CP performance of diffracted field is improved by introducing a pair of extra grounds. A 16 × 16 planar PLWA is further constructed using the 1 × 16 PLWA. And it has an impedance bandwidth of 52.5% (4.5 GHz – 7.7 GHz) and a CP bandwidth of 34.6% (4.5 GHz – 6.38 GHz) in the experiment. The frequency scanning range is from -58° to 48°, while the CP coverage is from -58° to 13°. The proposed antenna features a wide band and wide coverage, which could be a good candidate for wireless and radar applications.

Circularly Polarized Leaky-Wave Antennas Based on Periodically Arranged Rotated Right-Angle Triangular Microstrip Patches

In this paper, a scheme to realize the circularly polarized periodic leaky-wave antennas is prosed. A single-row model and a dual-row model are presented based on the series-fed periodically arranged rotated right-angle triangular (RAT) microstrip patches. For either of the two models, the antenna unit of one period occupies four RAT microstrip patches and the units are arranged repetitively on one side or on both side of a transmission line. The open-stopband is eliminated by adjusting the distances between the patches in each unit. The single-row model with 12 units on one side of a transmission line achieves a main beam sweeping angle range of 96° (-56°-40°). The model realizes the left-hand (LH) circular polarization as the main beam is scanning continually from -19° to 22°. The dual-row model includes 20 units of a different form of the rotated RAT microstrip patches arranged on both side of a transmission line. The main beam is able to scan from - 40° to 35° while the antenna is radiating. The model realizes the LH circular polarization while the main beam is scanning from -18° to 13°. The proposed two models can both realize circular polarization and continual beam scanning across the broadside.

Circular Airy-like beams through leaky-wave antennas

A planar nonuniform radially periodic leaky-wave antenna is proposed for the generation of circular, azimuthally symmetric Airy beams. The design is compact and low cost, and it is excited by an integrated coaxial cable. An annular metal strip grating is considered as background structure, designed to support a fast, backward, radially propagating space harmonic, which is capable of generating nondiffracting fields. The period and slots width are then properly modulated to synthesize the relevant Airy-like aperture-field distribution. An approximate formula is proposed to describe the aperture field, which is then used to retrieve the pattern of the annular strips. The near field produced by the structure is evaluated through the radiation integral, and validated by means of numerical full-wave simulations.

A Broadband Bidirectional Circularly Polarized Phase-Inverter-Based Periodic Leaky-Wave Antenna With Same Handedness

A Broadband Bidirectional Circularly Polarized Phase-Inverter-Based Periodic Leaky-Wave Antenna With Same Handedness

Novel Design Methodology for 3D-Printed Lenses for Travelling Wave Antennas

A novel methodology is introduced for designing bespoke homogeneous and graded index lenses for enhancing the gain of travelling wave antenna arrays (TWAs). 3D-printed lenses in the literature are majorly explored with standing wave antennas (SWAs) such as a microstrip or a horn antenna for gain enhancement. As there is progressively less power radiated from each slot in a TWA, as well as the successive phase delay between slots, the existing lens design approaches used for SWAs is not optimal for TWAs. Accordingly, we present a new approach of introducing a curvature to the lens that is derived from studying the power radiation profile of each slot of the TWA. This new methodology is demonstrated on a dielectric filled waveguide (DFW) slot array antenna operating at 26 -30 GHz band. An optimized dielectric graded lens and an optimized homogeneous lens have both been designed, fabricated, and measured with the DFW slot array. The new lens demonstrated a gain enhancement of more than 7 dB compared to less than 4 dB with conventional dielectric lenses. The proposed lens theory has been further verified with a bespoke optimized lens for a periodic stub-loaded microstrip leaky-wave antenna with a beam-scanning of 65∘. Design rules are included that can be applied for any TWA.

A Lateral Scanning Periodic Leaky-Wave Antenna Using Reverse Dipole Pair Element for Suppressing -2nd Space Harmonic

This communication presents a periodic leaky-wave antenna (PLWA) with a lateral scanning beam, in which the basic element is composed of a reverse dipole pair (RDP). The operating mechanism of the RDP is first investigated, and it is found that the -2nd space harmonic (SH) is effectively suppressed by loading the reverse dipoles in the center of the periodic element. Meanwhile, the -1st SH is strengthened. Next, two rows of improved directors are introduced to reduce the broadside radiation and compress the beamwidth in the lateral direction. Finally, the element configuration is optimized to eliminate the open-stopband effect in the periodic structure. A prototype of the proposed RDP-based PLWA is fabricated and measured, and it is found that the -2nd SH at 9 GHz is suppressed, and a large front-to-back ratio of nearly 20 dB is achieved at 7.4 GHz in the exact lateral direction. The proposed antenna with single-mode operation provides more choices for low-profile beam scanning systems.

Circularly Polarized Beam-Steering Microstrip Leaky-Wave Antenna Based on Coplanar Polarizers

A periodic frequency-scanning one-dimensional microstrip leaky-wave antenna with circular polarization is proposed in this letter. The introduction of the novel square patch and stub, which are printed on the same layer of the microstrip array, can effectively transform the polarization type into left-handed circular polarization (CP). The two parasitic elements in each unit cell can be excited by the host meandering microstrip line without extra feeding networks, which introduce one orthogonal polarized wave to satisfy the condition of CP radiation. A prototype includes nine modified unit cells is fabricated and measured. The designed antenna covers an impedance bandwidth over 26.1% with | <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">S</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sub> | < −10 dB and a CP bandwidth over 11.2% with |AR|< 3 dB in the measurement. The main beam scans from −4° to 18° in the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">yoz</i> plane (beam scanning plane) through broadside direction (0 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">°</sup> ) while maintaining good CP property.

A High-Gain Endfire Periodic Leaky-Wave Antenna Using DSPSL-Based Rhombic Element

An endfire periodic leaky-wave antenna (LWA) with high gain is presented in this communication, which consists of a series of rhombic elements based on double-sided parallel stripline (DSPSL). The endfire mechanism of the proposed antenna is illustrated by the phase difference of the far field of each arm in the rhombic element. Meanwhile, a tradeoff between the tilted angle <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\theta _{0}$ </tex-math></inline-formula> and the width <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$w$ </tex-math></inline-formula> is found, which assures an optimum transverse aperture for achieving high-gain endfire radiation. Moreover, the improved Hansen–Woodyard (IHW) condition is applied to predict the optimum endfire phase constant. Finally, a prototype is fabricated and tested. The maximum endfire gain of 19.8 dBi is measured at 11.4 GHz, which is close to the simulated and predicted results. The proposed periodic rhombic antenna provides more choice for the modern communication system.