Microstrip Leaky-wave Antenna Research Articles

Dual-Beam Steering Microstrip Leaky Wave Antenna With Fixed Operating Frequency

A fixed-frequency dual-beam steering microstrip leaky-wave antenna is presented in this paper. A novel equation with finite-difference time-domain method is proposed to calculate the complex propagation constant of microstrip leaky-wave antenna. The microstrip leaky-wave antenna is excited by multiterminals. By control the novel feeding configuration, the microstrip leaky-wave antenna has the advantage of main lobe's dual-beam and steering at fixed-frequency. The main lobe steers from 41 to 63 for right beam and from 117 to 139 for left beam symmetrically when operating frequency fixes at 7 GHz. This new microstrip leaky-wave antenna can easily be used as collision avoidance or automobile radar system.

Two-dimensional beam-scanning microstrip leaky-wave antenna

A novel two-dimensional beam-scanning microstrip leaky-wave antenna (MLWA) is presented. The proposed antenna consists of two half-width MLWA with a phase-shifter. This new type of MLWA has the advantages of two-dimensional beam-scanning and suppressing back lobes. This reduced size MLWA is useful in automotive radar systems and air traffic control.

Analysis of a Microstrip Leaky-Wave Antenna Loaded with Shorted Stubs

A new theory is provided to analyze a novel microstrip leaky-wave antenna (MLWA) with shorted stub loading, used for fixed-frequency beam steering applications. Formulas for calculating the radiation angle of MLWA with stub loading are deduced. The radiation angle estimated theoretically agrees very well with the rigorous numerical result calculated with the finite difference time domain (FDTD) method. This new theory can be used to explain the MLWA behavior with any reactive element loading, if the input admittance of the reactive element is known.

High Efficiency and Broadband Microstrip Leaky-Wave Antenna

A novel layout of leaky-wave antennas based on tapered design has been proposed and investigated. The new tapered leaky-wave antenna (LWA) was designed running a simple procedure which uses an FDTD code, and using a suitable metal walls down the centerline along the length of the antenna connecting the conductor strip and the ground plane, which allows to use only half of the structure, the adoption of a simple feeding, and the reduction of sidelobes. The good performance of this new tapered microstrip LWA, with reference to conventional uniform microstrip LWAs, is mainly the wider band of 33% for VSWR<2, higher gain (12 dBi), and higher efficiency (up to 85%). Furthermore, from the theoretical analysis we can see that, decreasing the relative dielectric constant of the substrate, the bandwidth of the leaky-wave antenna becomes much wider, improving its performance.

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.

Microstrip leaky‐wave antenna with beam‐patterns switchable capability

AbstractA beam‐patterns switchable microstrip leaky‐wave antenna (MLWA) is presented in this letter. A new feeding configuration of MLWA has been shown. MLWA fed with two feeding terminals on different sides radiates out single‐beam radiation patterns. Through controlling SPDT switch, the beam‐patterns change from single‐beam mode to dual‐beam mode. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 3060–3063, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22949

A simple design of broadband tapered leaky‐wave antenna

AbstractA new layout of leaky‐wave antennas based on tapered design has been proposed and investigated. The new curve tapered leaky‐wave antenna (LWA) was designed running a simple procedure which use an FDTD code, and using a physical grounding structure along the length of the antenna, which allows to use only half of the structure, the adoption of a simple feeding, and the reduction of sidelobes. The good performance of this new tapered microstrip LWA are mainly wider band of 33% for VSWR <2, higher gain (12 dBi) and higher efficiency (up to 85%). Moreover if the relative dielectric constant of the substrate approaches 1 (ϵr=ϵ0), the leaky wave antenna bandwidth becomes much wider improving its performance. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2833–2838, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22860

Fixed-Frequency Dual-Beam Scanning Microstrip Leaky Wave Antenna

A fixed-frequency dual-beam scanning microstrip leaky-wave antenna (MLWA) is presented in this letter. Through controlling the novel feeding configuration, MLWA has the advantage of dual-beam scanning at the fixed frequency. The main lobe scans from 41.16deg to 63.01deg for the right beam and from 116.75deg to 138.59deg for the left beam when operating frequency fixes at 7 GHz.

Circularly-polarised microstrip leaky-wave antenna

A novel circularly polarised microstrip leaky-wave antenna is proposed and tested. Two linear polarised orthogonal dual-terminals feeding microstrip leaky-wave antennas are fed with equal amplitude and 90° phase difference to generate the two orthogonal modes. The measured results show that the antenna achieves circular polarisation efficiently.

Design of Conformal Tapered Leaky Wave Antenna

The bend structure of leaky-wave antennas based on curve tapered design has been proposed and investigated. The new leaky-wave antenna (LWA) was designed running a simple procedure which use an FDTD code, and using a physical grounding structure along the length of the antenna, which allows to use only half of the structure, the adoption of a simple feeding, and the reduction of sidelobes. The good performance of this new tapered microstrip LWA are mainly wider band, higher gain, and higher e-ciency whit reference to conventional uniform microstrip LWAs. Bending the curve tapered LWA, the major performance noticed of this antenna were the wider beam of radiation pattern and a further reduction of back lobes. Moreover since the tapering of linear LWA involves the variation of both phase and leakage constant, all the emitted rays are focused in a corresponding angular interval, allowing to obtain from the ray optical model a closed formula to predict the main beam angle of linear and curve taper LWA. Finally from theoretical analysis it should be appreciated that, as the relative dielectric constant of the substrate approaches 1, the leaky wave antenna bandwidth becomes much wider, improving its performance.

Reactive loaded microstrip leaky wave antenna for low cost beam steering applications

AbstractA novel fixed frequency beam scanning microstrip leaky wave antenna is reported. The beam scanning at fixed frequency is achieved by reactive loading. Simulation and measured results shows frequency scanability of 80° as well as fixed frequency beam steering of 68° over the −10 dB impedance band of 4.56–5.06 GHz © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 2299–2301, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21912

Frequency-fixed beam-scanning microstrip leaky-wave antenna with multi-terminals

New frequency-fixed beam-scanning microstrip leaky-wave antennas are reported. The beam-scanning ability at a fixed frequency of the antenna can be achieved with novel feeding configurations. Simulation and measurement results show the new feeding structure can make the main lobe gradually scan from 50 to 80° in H-plane when the frequency fixes at 1.12 GHz.

A novel electronically scannable log‐periodic leaky‐wave antenna

AbstractAn innovative phaseshifterless, wideband, microstrip leaky‐wave antenna with an electronically steerable dual‐pencil‐beam pattern in the H‐plane is presented. The log‐periodic geometry of the leaky slots of the antenna results in a wide bandwidth of 25.19%. The fan beam can be steered up to 14° over the wide resonating band of the antenna. The beam is also steerable at a fixed frequency, by reactivelty loading the slots and a maximum steering angle of about 14° is observed for different capacitor values with an improved bandwidth of 33.3%. This concept is studied using passive components, but it can be extended to varactors. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 45: 163–165, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20757

24‐line of Brillouin‐Erbium fiber laser utilizing a Fabry–Pérot cavity in L‐band

AbstractIn this paper, the generation of a multiwavelength laser source from a Brillouin‐Erbium fiber laser in the long wavelength band (L‐band) region is experimentally demonstrated. The proposed laser system utilizes a Fabry–Pérot cavity formed by fiber‐loop mirrors. Twenty‐four lines of Brillouin–Stokes with line spacings of 10 GHz are obtained in the L‐band region. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 45: 165–167, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20758

Effects of Multilayers Superstrates on Microstrip Leaky-Wave Antennas Radiating Characteristics and Performances

In this paper, a full-wave accurate and versatile solution for multilayers superstrates on microstrip leaky-wave antenna analysis is described. Therefore, setting E and J continuity conditions on radiating aperture provides, a systematic formulation of the integral equation by a periodic discontinuity network where the concept of trial functions is introduced. Since current density is established by analytical expressions, the relevant equation is solved numerically by Galerkin method. The propagation constant of the leaky-wave is obtained by a least squares method. Hence, electronic beam scanning applications and performances are investigated upon layers thickness and dielectric values. Several examples are given and discussed.

Single-Conductor Strip Leaky-Wave Antenna

This paper presents a leaky-wave antenna with only a single-conductor strip on a substrate without a practical ground plane. The full-wave integral equation method is used to investigate the EH/sub 01/ leaky mode of this single-conductor strip structure. When this single-conductor strip is on a thin substrate with a low dielectric constant, a broad-band radiation regime can exist for the EH/sub 01/ leaky mode. The balanced microstrip lines and the inverted balanced microstrip lines are used to excite this EH/sub 01/ leaky mode. This work presents both the numerically simulated and measured data. The measured bandwidth of a voltage standing-wave ratio /spl les/2 is from 6.55- 13.75 GHz (2.34:1). In this case, the normalized phase constant is very close to 1 and this results in a fixed main-beam radiation pattern in the end-fire direction. This leaky-wave antenna with only a single rectangle stripline of length 110 mm can achieve the same broad-band performance as a tapered microstrip leaky wave antenna with a length 310 mm, as previously reported by the authors.

Electronically scanned composite right/left handed microstrip leaky-wave antenna

A novel electronically scanned periodic microstrip leaky-wave (LW) antenna based on the concept of composite right/left-handed (CRLH) metamaterials is presented. This antenna includes varactors modulating the capacitive loading of the unit cell and therefore the propagation constant of the structure, which results in voltage scanning of the radiated beam. An accurate circuit model is proposed. The antenna is demonstrated experimentally to exhibit continuous scanning in the dominant mode from backward to forward angles. The scanning range is from -10/spl deg/ at 35 V to +7.5/spl deg/ at 0 V, and broadside occurs at 9 V, at the fixed frequency of 3.23 GHz.

Novel modal properties and relevant scanning behaviors of phased arrays of microstrip leaky-wave antennas

In this work, different previously unexplored features are investigated for the radiation performance of linear phased arrays based on printed-circuit leaky-wave antennas for microwave and millimeter-wave applications. By means of a rigorous modal analysis in the unit cell based on the spectral-domain approach, we have considered the beam-scanning properties of microstrip leaky-wave arrays in terms of spatial harmonics, as a function of both the phase shift and the spacing between the radiating microstrip lines. We have thus found and interpreted in a consistent way various original characteristics, such as transition regions between leaky-wave and surface-wave regimes, and the occurrence of spurious radiation (grating lobes) in largely spaced arrays related to the presence of new, additional complex improper modes. Numerical full-wave simulations of the radiation patterns for realistic configurations of microstrip arrays confirm the theoretical predictions made on the basis of the modal properties of the involved leaky waves.

Broadband tapered microstrip leaky-wave antenna

This study proposes a novel scheme based on the characteristics of leaky-wave antennas for the empirical design of broadband tapered microstrip leaky-wave antennas. This scheme can explain and approximately model the radiation characteristics of a linearly tapered leaky-wave microstrip antenna. A broadband feeding structure that uses the balanced and the inverted balanced microstrip lines to form a pair of broadband baluns is also presented. The measured return loss of the inverted balanced microstrip lines has a VSWR/spl les/2 from dc to 18.6 GHz and that of the back-to-back feeding structures has a VSWR/spl les/2 from 2.2 to 18.6 GHz. This feeding structure can be used to feed a broadband planar leaky-wave antenna with a fixed mainbeam that uses the tapered microstrip structure. The measured bandwidth of the antenna for a VSWR/spl les/2 exceeds 2.3:1.

The nature of the end-of-scanning region in printed-circuit arrays of leaky-wave antennas

In this work, some original behavioral features of printed-circuit arrays of leaky-wave antennas have been investigated. In particular, by means of a rigorous spectral-domain approach in the unit cell, we have studied the end-of-scanning operation of a microstrip leaky-wave antenna array as a function of the phase shift between elements. A careful analysis in terms of the involved proper and improper spatial harmonics has shown that a transition region exists for the operating mode from a spatial leaky-wave regime to a surface-wave regime. This transition corresponds to the radiated beam hitting the array plane and evolving through a previously unexplored phase gap into a surface wave propagating at an angle with respect to the microstrip line sources. Such finding allows us to achieve a more complete view of the radiation properties of this class of scanning antennas.