Half-width Microstrip Leaky Wave Research Articles

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

<p class="Default">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.</p>

Radiation beam scanning for leaky wave antenna by using slots

This paper provides an insight of a new, microstrip leaky wave antenna. It holds the ability to continue steer its beam at a swapping frequency. 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 band frequency via vertical and horizontal slots. The enhancement is realized by etching horizontal and vertical slots on the radiation element. This study also presents a novel half-width microstrip leaky wave antenna (LWA). The antenna is made up of the following basic structures group’s vertical and horizontal slots. 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 radiation pattern direction changes by sweeping the operating frequency between 4 GHz to 6 GHz.The main beam may be directed by the antenna between 15 o and 55 o . C band achieved the measured peak gain of the antenna of 10 dBi at 4.3 GHz beam scanning range.

Enhancement of boresight radiation for leaky wave antenna array

An array of half-width microstrip leaky-wave antennas (HW-MLWAs) of two uniform elements was designed to obtain maximum boresight radiation. Achieve this, two uniform of HW-MLWAs are placed at 180◦ and fed by a probe located at the center between the elements, two uniforms of HW-MLWAs, loaded terminated by 50Ω lumped element. Two beams from two branches individual merge to form the resultant directive beam. The simulation represents the susceptibility of the proposed array of uniform HW-MLWAs to the radiation broadside direction effectively. The predict bandwidth matched of the array is 582 MHz (4.18–4.76 GHz). The direction of its main beam in boresight happens over a wide 13%, relatively (4.18-4.76 GHz) band. The proposed peak gain at the boresight direction of the array is 9.91 dBi.

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.

Forward and Backward Beam-Scanning Tri-Band Leaky-Wave Antenna

The main limitations of uniform half-width microstrip leaky-wave antennas (HW-MLWAs), namely a single operating band and only forward beam scanning, are overcome here with an HW-MLWA loaded with periodic L-shaped slots. The antenna exhibits tri-band operation, and the main beam can be steered in the forward direction in one band, and in the backward direction in the other two bands. Its size is halved with a shorting wall. The antenna was fabricated and tested to validate the concept, and the measured and simulated results agree very well. The measured matched (10-dB return loss) bandwidths of the prototype are 22.34 $\%$ (5.05–6.32 GHz), 15.85 $\%$ (8.77–10.28 GHz), and 11.21 $\%$ (12.63–14.13 GHz) in the first, second, and third bands, respectively. The beam-scanning ranges of the prototyped antenna are 30 $^\circ$ to 64 $^\circ$ , $-\text{75}^\circ$ to $-\text{18}^\circ$ , and $-\text{19}^\circ$ to $-\text{4}^\circ$ when the frequency sweeps from 5 to 6 GHz, 8.85 to 10.5 GHz, and 13 to 14.25 GHz, respectively. The measured peak gains (within the scanning range) are 12.4, 14.3, and 14.7 dBi in the first, second, and third bands with variations of 2.5, 3.4, and 3.1 dB, respectively.

Periodic U-Slot-Loaded Dual-Band Half-Width Microstrip Leaky-Wave Antennas for Forward and Backward Beam Scanning

Half-width microstrip leaky-wave antennas (HW-MLWAs) are generally single band. Here, we present a new method to achieve dual-band operation from an HW-MLWA by periodically loading the antenna with U-shaped slots. These dual-band MLWAs are able to steer the beam in forward directions in one band and in backward directions in the other band. One of the antenna designs was prototyped and tested, and excellent agreement between the predicted and measured results were observed. The measured 10-dB return loss bandwidth of the first and second bands are $19.5 \% $ (5.24–6.37 GHz) and $13.2 \% $ (7.9–9.02 GHz), respectively. The antenna can steer the main beam from $30^\circ $ to $65^\circ $ in the first band and from $-46^\circ $ to $-10^\circ$ in the second band by sweeping the frequency from 5.25 to 6.25 GHz and 7.75 to 9 GHz, respectively. The measured peak gain of the antenna is 12.2 and 14.1 dBi in the first and second bands, respectively. Although the antenna parameters are optimized for dual-band operation, the radiation properties in another higher frequency band (third band) are also explored. In the third band, the antenna beam continuously scans from backward to forward direction as frequency increases. Moreover, this U-slot loaded single-layer half-width LWA is easy to fabricate.

An Array of Half-Width Microstrip Leaky-Wave Antennas Radiating on Boresight

An array of four uniform half-width microstrip leaky-wave antennas (MLWAs) was designed and tested to obtain maximum radiation in the boresight direction. To achieve this, uniform MLWAs are placed at 90 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">°</sup> and fed by a single probe at the center. Four beams from four individual branches combine to form the resultant directive beam. The measured matched bandwidth of the array is 300 MHz (3.8-4.1 GHz). Its beam toward boresight occurs over a relatively wide 6.4% (3.8-4.05 GHz) band. The peak measured boresight gain of the array is 10.1 dBi, and its variation within the 250-MHz boresight radiation band is only 1.7 dB.

Full-Wave Analysis and Design of Circular Half-Width Microstrip Leaky-Wave Antennas

A half-width microstrip leaky-wave antenna on a circular substrate is proposed and investigated. A microstrip on a circular substrate has a broader bandwidth for free-space leaky-wave radiation than a planar microstrip. A half-width microstrip has similar radiation characteristics to a full-width microstrip, but it does not require complex feeding structures. Full-wave analysis based on the extended spectral domain approach (ESDA) is applied to analyze the propagation characteristics of the circular half-width microstrip. The ESDA accounts for field singularities near a conductor edge of finite thickness and it does not require a virtual boundary to obtain the finite extent of the analytical space. Consequently, the ESDA is more suitable for analyzing leaky-wave structures than other conventional analysis methods. Numerical calculations are performed to determine the characteristics of the leaky-wave radiation from half-width microstrips on circular and semicircular substrates. The leaky radiation elements can be efficiently designed based on these numerical results. Two practical antennas with leaky radiation elements and feeders are designed and implemented. The measured bandwidths of the free-space leaky-wave radiation indicate that these cylindrical antennas have better performances than planar ones and they are in reasonable agreement with theoretical results. The measured radiation patterns with frequency-scanning characteristics also agree well with the simulation results.

The Half-Width Microstrip Leaky Wave Antenna With the Periodic Short Circuits

A half-width microstrip leaky wave antenna (LWA) with periodic short circuits is presented. The backward-to-forward beam-scanning capability is achieved by periodic construction. The proposed antenna consists of a long rectangular patch with the short circuits that are placed with a series of shorting pins between the antenna patch and the ground plane periodically. The measurement results show that the main lobe scans electronically from 144° to 41° in H-plane (y-z plane) toward endfire (+z direction) with an open stopband when the operating frequency is increased from 4.4 GHz to 8.8 GHz.

The Periodic Half-Width Microstrip Leaky-Wave Antenna With a Backward to Forward Scanning Capability

The periodic half-width microstrip leaky wave antenna (MLWA) with a backward to forward scanning capability is presented in this paper. The proposed antenna consists of a series of half-width MLWA. The radiating periods place on the different sides of the transmission line. The radiating period works in cutoff region of the first higher order mode, the periodic construction radiates the slow wave out along the edge. The experimental results show the main lobe scans electronically and continuously from 149° to 28° in H-plane ( y-z plane) toward end fire (+ z direction) when the operating frequency increases from 4.2-.9 GHz.

Quasi Microstrip Leaky-Wave Antenna With a Two-Dimensional Beam-Scanning Capability

A quasi microstrip leaky-wave antenna (QMLWA) with a two-dimensional (2-D) beam-scanning capability is presented in this paper. QMLWA consists of two half-width microstrip leaky-wave antennas with a phase-shifter. This new type of microstrip leaky-wave antenna has the advantages of reducing size, 2-D beam-scanning and suppressing back lobes. The main lobe scanning in H-plane ( <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">y</i> - <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">z</i> plane) is achieved through varying the operating frequency. When the operating frequency increases from 4.4-6 GHz, the main lobe scans from 84deg to 26deg in H-plane continuously. The main lobe steers in quasi-E-plane with varying the phase difference between two half-width microstrip leaky-wave antennas. The lobe scans from 78deg to 103deg in quasi-E-plane at 5.4 GHz. The experimental results show this short QMLWA (about 2 wavelengths) leaks power effectively. The back lobe in H-plane of QMLWA is suppressed 13 dB as compared with the conventional whole width MLWA at 5.4 GHz as example. The H-plane radiation characteristics of QMLWA are mainly determined by the width <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">s</i> of half-width MLWA and the distance <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">D</i> between two half-width MLWA together. This size-reduced QMLWA is useful in the automotive radar system and air traffic control.