Microstrip Leaky-wave Antenna Research Articles

A Microstrip Leaky-Wave Antenna with Scanning Beams Horizontal to the Antenna Plane

A Microstrip Leaky-Wave Antenna with Scanning Beams Horizontal to the Antenna Plane

Meandering Microstrip Leaky Wave Antenna With Dual-Band Linear–Circular Polarization and Suppressed Open Stopband

Meandering Microstrip Leaky Wave Antenna With Dual-Band Linear–Circular Polarization and Suppressed Open Stopband

Microstrip Leaky-Wave Antenna With Circular Polarization and Broadside Radiation

In this letter, a novel circularly polarized microstrip leaky-wave antenna is proposed with broadside radiation and high gain. A conventional microstrip patch has been modified to obtain broadside gain along with circular polarization. The modified patch is periodically placed along one side of the 50 Ω delay line to form leaky-wave antenna. The optimized broadside frequency of the antenna is 10.1 GHz. The bandwidth associated with 3-dB axial ratio is 13.3% while the maximum obtained gain is 15.8 dBic. The measured gain variation within 3-dB axial ratio bandwidth is 1.6 dB. Measured results of the fabricated antenna follow the simulations.

Bandwidth and Gain Enhancement of Microstrip Leaky-Wave Antennas with Slot and Defected Ground Structure

This paper discusses the design, simulation, and realization of a leaky-wave microstrip antenna with multiple slots and defected ground structure (DGS). The leaky-wave microstrip antenna with multiple slots and DGS was designed to operate at 5.925-6,425 GHz for wireless local area network applications (WLANs), with a gain of ≥4dBi. The antenna uses FR-4 epoxy as the substrate with a dielectric constant of 4.6 and a thickness of 1.6 mm. The leaky-wave microstrip antenna has dimensions of 45.1 mm × 24.8 mm × 1.6 mm, while the leaky-wave microstrip antenna with multiple slots and DGS has dimensions of 40.6 mm × 25 mm × 1.6 mm. The simulation results showed that adding multiple slots and DGS to the leaky-wave microstrip antenna increased the bandwidth from 280 MHz (5.859–6.139 GHz) to 691 MHz (5.854–6.545 GHz) while the gain increased from 4.47 to 5.04 dBi. Meanwhile, the measurement results showed that the bandwidth parameter increased from 273 MHz (5.877–6.150 GHz) to 684 MHz (5.845–6.529 GHz) and the gain parameter from 4.53 to 5.06 dBi at 6 GHz.

Influence Of Patchs Shape On The Radiation Performance a Microstrip Leaky-Wave Antenna

In this article, we present microstrip leaky wave antennas designed using HFSS software. These microstrip antennas differ in the shape of the patches on the substrate. To this Effect, three shapes have been studied and the analysis of the radiation parameters of these antennas shows that the T-shape patches have low levels of minor's lobes and good the scanning angle in the E- and H-plane compared to the other studied shapes. This study of the influence of the patches shape on the performance of microstrip leaky wave antennas shows the impact on the radiation pattern and directivity of the antenna. Through a comparative study of three patch shapes H, inverted T and L, simulations show that inverted T patches have low the levels of minor’s lobes and good the scanning angle in the E and H planes compared to the other shapes studied. However, the L-shape present a better directivity compared to the other shapes.

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.

Communication Compact Microstrip Leaky-Wave Antenna for Wide-Angle Beam Scanning With Circular Polarization

In this communication, a meandered microstrip line leaky-wave antenna (LWA) is proposed with circular polarization (CP), high radiation gain, and wide beam scanning range. The utilization of periodical meander technology in the microstrip line format not only leads to structure compactness, but also generates a higher space harmonic for beam scanning characteristics. The leakage rate and CP generation are controlled by the titled angle and width ratio of the meandered line, respectively. In addition, two shunt grounded stubs and one isolation wall between inclined arms are employed in each period to suppress the open stopband (OSB) effect and improve the radiation performance through a wide beam steering range. Compared with other similar designs, the proposed antenna shows advantageous characteristics of extremely simple structure (single-layer), compact size ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.23\lambda _{0} \times 6.0\lambda _{0} \times 0.04\lambda _{0}$ </tex-math></inline-formula> , <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\lambda _{0}$ </tex-math></inline-formula> is the free space wavelength at the broadside frequency, i.e., 13.1 GHz), wide functional beam scanning range with CP (43.5%) and high radiation gain (15.5 dBic), which satisfies the increasing demand for the miniaturization and integration of frequency-dependent devices.

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.

ARIEL: Passive Beam-Scanning Antenna teRminal for Iridescent and Efficient LEO Satellite Connectivity

A novel low-cost high-gain beam-steering antenna terminal topology for global data connectivity with low-earth-orbit satellite constellations in the UHF 900 MHz ISM band is reported. It is shown how a simple printed-circuit-board half-width microstrip leaky-wave antenna (LWA) with passive frequency-beam scanning capacity provides an energy-efficient scanning method avoiding more power-demanding and expensive beam-steering techniques (such as electronic scanning, mechanical rotation, or beam switching). For that, iridescent channel-agile operation and cross-layer optimization are needed. As an example, two single-element LWAs and an LWA array are designed to scan the celestial vault with an angular elevation scanning range of 130° and using the available LoRaWAN protocol channels from 902 to 928 MHz. It is reported a scanned-beam peak gain above 9 dBi for the compact printed-circuit LWA array design with 55 cm × 27 cm aperture dimensions.

Dual-mode microstrip leaky-wave antenna for pattern diversity application.

We present a dual-mode microstrip leaky-wave antenna (LWA), which is characterized by radiating a single beam or dual symmetrical beam. Different from the conventional single-mode microstrip LWA, the designed antenna is based on the odd mode and the even mode of the employed shorted microstrip line. The working principle of these two modes is fully studied by analyzing the electric-field distributions and their dispersion curves. Additionally, it can be found that the odd mode and the even mode are capable of realizing different radiation patterns. Furthermore, a mode translator is particularly designed in order to efficiently excite the concerned two modes. Finally, the presented antenna is simulated, fabricated, and measured, and the simulated results agree well with the measurements. The tested far-field results show that the designed dual-mode LWA realized single-beam scanning from 39° to 64° when the frequency ranges from 4.5 to 5.0 GHz and dual symmetrical beam scanning from 44° to 60° as the frequency varies from 4.5 to 4.9 GHz, respectively.

Dual-Frequency Microstrip Leaky-Wave Antenna for High-Gain Broadside Radiation

This article presents a resonator-fed dual-frequency dual-mode bidirectional leaky-wave antenna to provide attractive high-gain broadside radiation at dual desired frequencies. First, by analyzing the dispersion diagrams of the first (EH <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> ) and third (EH <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> ) higher order modes of a microstrip line, it is theoretically verified that these two modes can both be suitably employed for bidirectional leaky-wave antenna design. In addition, it is also determined that the ratio between these two operation frequencies can be handily controlled by appropriately loading periodical shorting pins along the nodal lines of the EH <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> modal field. As such, the dual-frequency operation principle is thoroughly investigated and determined. Afterward, to effectively excite the desired modes and suppress any unwanted modes of the microstrip line, a dual-frequency resonant-fed strategy is adopted. More specifically, the introduced feeding resonator is first fed by a pair of differential probes, and then, the microstrip EH <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> and EH <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> modes are excited through the coupling gap. In this way, the desired pure EH <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> and EH <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> modes are successfully excited. As an example, a dual-frequency bidirectional microstrip leaky-wave antenna is designed to work at 3.6 and 4.9 GHz, and its prototype is simulated, fabricated, and tested. The obtained far-field radiation patterns from simulations and measurements show a reasonable agreement, and the concerned high-gain radiation at the broadside is well achieved at both frequencies.

Dual-Resonant Wideband Microstrip Annular Sector Patch Antenna With Increased Backfire Radiations

A novel design approach to wideband, dual-resonant microstrip annular sector patch antenna (MASPA) is proposed. As mathematically revealed by the dominant eigen-equation, MASPA with increased backfire radiation can be evolved from a truncated microstrip leaky-wave antenna. Then, the general relationships between the ratios of outer/inner radii, flared angles, and operational modes are deduced. The outer arc of the annular sector patch is set as a magnetic wall or open-circuited while the inner one is set as an electric wall or short-circuited, such that the patch’s size could be accordingly reduced by 13% to the circular sector case. As finally validated, a dual-resonant MASPA with a flared angle of 150°, outer/inner radii ratio of 3.0, and backfire gain up to 4.0 dBi can be implemented on single-layered air substrate with a height of 0.043-wavelength at the center frequency. Therefore, the advanced design approach can effectively realize patch miniaturization, wide band, and increased backfire radiation without inquiring extra multiple radiators and incorporating any additional reactance compensation techniques.

A tunable ⵣ‐shaped microstrip leaky wave antenna based on liquid crystal

SummaryThis article presents an electrically tunable dual‐beam ⵣ‐shaped microstrip leaky wave antenna (MLWA) based on liquid crystal (LC). A new ⵣ‐shaped microstrip component (Berber's alphabet: pronounced |z|) is proposed as a single unit‐cell to achieve a dual‐beam radiation pattern with adjustable dual‐beam angles controlled by the ⵣ‐shaped length‐to‐width ratio. The dual‐beam radiation pattern of ⵣ‐shaped microstrip is theoretically derived. The tunable dual‐beam scanning is achieved using a nematic liquid crystal (N‐LC). An AC voltage controls the permittivity of N‐LC applied on the inverted radiating metal. The orientation angle of the N‐LC molecules is also determined theoretically. Besides, the MLWA is rearranged due to the meandering configuration of its microstrip transmission lines, which reduces the antenna's size. As a result, this antenna has a symmetrical dual‐beam at a pointing angle of ±37° in the YZ‐plane. Furthermore, the proposed MLWA is tuned up to 25° at a fixed frequency in XZ‐plane directions by applied AC voltage from 0 to 20 V, which changes the permittivity of the N‐LC from 2.47 to 3.25, respectively. Meanwhile, the MLWA has a realized gain of up to 7.5 dB and a beam scanning range of 40° in the XZ‐plane for all operating frequencies. Finally, the proposed antenna can be suitable for satellite and radar communication systems.

Compact EH0-Mode Microstrip Leaky-Wave Antenna With Enhanced Gain in Broadside

This article presents an EH <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> -mode microstrip leaky-wave antenna (LWA) with enhanced gain in broadside by bidirectionally exciting the inductive-loaded EH <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> -mode microstrip line (MSL). In this way, enhanced gain is successfully attained in broadside at the desired frequency. To theoretically investigate such an attractive property, an equivalent circuit model is first established to illustrate that the working frequency as well as the phase and leakage constants can be independently controlled by altering the shunt inductance and resistance, and further properly adjusting their quantities. Then, a row of shorting pins is appropriately loaded at one side of the MSL, so as to realize the inductive-loaded periodical leaky-wave structure for broadside radiation. After that, a more effective and practical transmission line model is derived to fully investigate the side pin-loaded MSL. Based on this transmission line model, an efficient method is proposed to design the working frequency and the values of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\beta /k_{0}$ </tex-math></inline-formula> and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\alpha /k_{0}$ </tex-math></inline-formula> in a controllable way. Furthermore, a gain enhancement of such an LWA is carried out with resorting to the directivity and radiation efficiency, aiming to acquire the maximum antenna gain. In final, the proposed EH <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> -mode LWA with broadside radiation is simulated, fabricated, and measured. Good agreement can be found between the simulated far-field radiation patterns and the tested ones, which both evidently indicate that a high-gain broadside radiation beam is indeed achieved at the desired frequency.

Increasing radiation power in half width microstrip leaky wave antenna by using slots technique

&lt;p class="Default"&gt;The radiation power in the endfire is decreased while the main beam of half substrate integrated waveguide scan from broadside to endfire in a forward. The design of half-width microstrip leaky-wave antenna (HW-MLWA) has been presented in this work to increase the power radiation near endfire by using the slots technique in the radiation element. This slot leads to a decrease the cross-polarization. The proposed design comprises one element of HW-MLWA with repeated meandered square slots in the radiation element. One aspect of this antenna is generated by using a half substrate integrated waveguide with a full tapered feed line. The proposed antenna was terminated by load of 50 Ω, and feed on the other end of the antenna. Finally, the suggested design is simulated and acceptable results were found. The released gain is increased from 10.6 dBi to 12 dBi at 4.3 GHz. This design is suitable for unmanned aerial vehicle UAVs at C band application.&lt;/p&gt;

Compact periodic leaky-wave microstrip antenna with periodic short circuits and forward-to-backward scanning capability

Compact size, elliptical polarization, a low-sidelobe-level microstrip leakywave antenna with short pins on one side of the sheet is described in the paper. The suggested antenna consists of 7 sheets that are periodically put on the antenna structure, with one of the edges of the sheet being incorporated with short-circuit pins. The proposed antenna has effective decrease in antenna size good scan capability, and reduction in sidelobe level in comparison with another types of antennas. A set of simple and effective equations is used to determine the operating range of the antenna. As elucidated by simulation results, the scanning process is carried out from 11° to –15°, at the rate of 26% as the frequency changes from 22.8 GHz to 27.8 GHz.

Design of dual‐band leaky wave antenna based on microstrip to EH 0 / EH 1 ‐mode converter

In this work, a microstrip leaky-wave antenna (LWA) under EH0/EH1-mode excitations is proposed for dual-band application. By introducing periodic shorting pins in the microstrip line, the leaky wave regions of EH0 and EH1-mode are created in two operation bands respectively. According to the electric field distribution of EH0 and EH1-mode, the equal phase feeding network is constructed to excite EH0-mode, while the EH1-mode needs the excitation with opposite phase feeding. To satisfy this special phase requirement in two operation bands, a dual-mode converter is designed based on a one-wavelength-ring balun, which provides two passbands with equal/opposite phase operations. To validate this proposal, a prototype of this dual-band LWA is designed and fabricated. The measured results exhibit that the proposed antenna could radiate beams under EH0-mode in 4.2 GHz and EH1-mode in 6.3 GHz.

An EH₀-Mode Microstrip Leaky Wave Antenna on Differentially Excited Coupled Line for Transversal Single-Beam Radiation

This communication presents a method to make the EH <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> -mode microstrip leaky wave antenna (MLWA) radiate single beam in its transversal plane based on the differentially excited coupled microstrip line structure with low cross-polarization. The conventional EH <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> -mode MLWA is constructed by periodically loading a series of shorting pins along the center line of the uniform line, but it mainly radiates dual beams in its transversal plane. If a ground plane approaches to one of its edges with rotation of the whole structure, only one radiation aperture will be left to radiate single beam in the broadside direction. Herein, a planar differentially excited coupled line configuration is implemented to validate the proposed method and simultaneously inherits the original outstanding characteristic of freely designed narrow strip width. In design, a unified equivalent model is first established to provide insight into its radiation principle through propagation characteristics. Then, the dispersion and radiation properties are further investigated under mixed geometrical parameters. Finally, a prototype MLWA with transversal single-beam radiation is designed and fabricated with good agreement between the simulated and measured results, which validates the proposed method for designing a single-beam EH <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> mode MLWA.

Study on Bandwidth Properties of EH1-Mode Microstrip Leaky-Wave Antenna for Broadside Radiation

An intuitive and effective analytical method is presented in this letter to investigate the bandwidth properties of the finite-length bidirectional EH <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> -mode microstrip leaky-wave antenna (LWA) for broadside radiation. First, a broadside radiation boundary curve is theoretically established in the complex <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">k</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">z</sub> = <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">β</i> – <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">jα</i> plane through the usage of the array factor. Afterwards, it is distinctively found that as the operating frequency is gradually enlarged, the EH <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> -mode wavenumber trajectory and the extracted boundary curve show opposite shifting tendency in the complex wavenumber plane, thus generating an intersection point, namely, boundary frequency, which is actually the upper limited frequency for broadside radiation. To verify the presented analytical method, a finite-length bidirectional EH <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> -mode LWA is practically analyzed and implemented. The theoretical and measured results both demonstrate that this LWA is capable of generating the desired narrow beam at broadside in a wide band up to 5.5 GHz, evidently validated the theoretically-predicted ones.

Microstrip leaky wave antenna for wide range of beam scanning in X band

AbstractIn this work, design of a pattern reconfigurable antenna is presented for X‐band applications as a leaky wave antenna (LWA) realization. Due to the advantages of simple design schematic, low profile, and easy impedance matching, LWA designs have been using as an efficient solution for reconfigurable antenna in many wireless communication applications. Optimization and simulation of the proposed LWA is carried out in 3‐D Microwave simulation CST environment and Honey Bee Mating is used as the optimization algorithm. Dimensions of the proposed LWA is 130 × 30 mm, which is fabricated on Rogers 5880 as capacitive loaded eight identical rectangular microstrip patches operating over 9.5‐12 GHz with a fractional bandwidth. The proposed LWA exhibits a measured peak gain of 11.8 dBi at 10 GHz with an overall gain characteristic of between 9.5 and 11.8 dBi over the range of 9.5 to 12 GHz with a steerable pattern characteristics between −45 and 50° as agreed with the theory. Furthermore, the fabricated LWA has been found to have the superior performance as compared with its counterparts.