Frequency Scanning Leaky Wave Antenna Research Articles

Compact 2-D Frequency Scanning Leaky-Wave Antenna Array with Cyclically Progressive Phase-Shifting Feeding Network

Compact 2-D Frequency Scanning Leaky-Wave Antenna Array with Cyclically Progressive Phase-Shifting Feeding Network

An SIW Pillbox-Based Compact Dual-Polarized Multibeam Antenna With Passive 2-D Beam Scanning Capability

In this brief, a dual-polarized multi-beam antenna is proposed based on substrate integrated waveguide (SIW) pillbox beamforming networks (BFNs). By using a rotationally symmetrical frequency scanning leaky-wave antenna (LWA) array and four SIW pillbox BFNs, the 2-D beam steering capability is realized for two polarizations. Due to the rotationally symmetrical geometric characteristic of the LWA, the orthogonally placed BFNs can excite orthogonally polarized beams. A stable gain with a wide beam scanning range in the limited bandwidth is realized, where only the backward to broadside scanning region of the LWA is used, and the forward radiation is compensated by the axisymmetric BFN. Moreover, the stacked layout of the multi-layer antenna structure greatly helps realize miniaturization. The proposed antenna can provide ±35° beam scanning range by switching 7 ports in the multi-beam plane and ±31° frequency beam scanning range within the bandwidth of 21 GHz to 27.5 GHz. The advantages of the proposed antenna, including dual-polarization, 2-D beam scanning, low profile, compact size, and low cost, make it a very appropriate choice in millimeter-wave multi-beam radars systems.

A Null Frequency Scanning Leaky-Wave Antenna

A new combline leaky-wave antenna (LWA) is proposed for null frequency scanning. The antenna contains a microstrip transmission line loaded with two groups of stubs on both sides. The two groups of stubs are placed periodically with two slightly different periods, providing two different <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 contribute to two radiation beams. Then, a null pattern can be realized, in which the null appears between the two beams and scans with frequency. The working principle is investigated. The antenna is designed, fabricated, and measured. Measurement results show that the antenna has a wide null-scanning range from −38° to 40° with a null depth below −24.0 dB, in an operation band from 9.9 to 13.8 GHz.

Direction Finding of RFID Tags in UHF Band Using a Passive Beam-Scanning Leaky-Wave Antenna

This work proposes a novel system for location applications of RFID tags in UHF band. The system is based on a frequency-scanning leaky-wave antenna (LWA), commodity hardware and Angle-of-Arrival (AoA) estimation of the signal reflected from RFID tags, by using only RSSI (Received Signal Strength Indicator) data. The LWA is completely passive, manufactured in simple printed technology and directly connected to the RFID reader. The dispersive nature of the LWA combined with the selection of a proper high permittivity substrate allows the radiation of frequency steered directive beams. The system is based on four directive beams created by the two-port antenna and two RFID channels to estimate the AoA by amplitude-monopulse signal processing and angular pseudospectrum technique. Thus, our approach is efficient, simple and low-cost, since the use of expensive or complex hardware required for electronic phased-array steering/beam-switching is avoided and the required computational load is low. Several experiments have been performed in different scenarios, reporting a wide FoV of 130&#x2218;, multi-tag detection and a RMSE of 8,1&#x2218;.

Annular Surface Plasmon Polariton-Based Frequency-Scanning Leaky-Wave Antenna for Full Azimuth Coverage

This article presents a single-layered annular surface plasmon polariton (SPP)-based leaky-wave antenna (LWA) for full azimuth beam scanning in 60 GHz applications. The groundless annular SPP transmission line (TL) has a special feeding mechanism that can be operated at 60 GHz in the SPP mode. Periodically radiating circular patches with gradually smaller sizes near the TL create an additional momentum that helps convert the slow wave SP mode into the radiating leaky mode. This results in frequency-dependent continuous beam scanning in the azimuth plane. The theoretical, numerical, and experimental results of the proposed device agree well. The antenna has an overall scanning range of 268°, −10 dB impedance BW of 15.33%, and a peak gain of 19.7 dBi with an average sidelobe level (SLL = −10 dB) and a cross-polar level of −20 dB. Owing to the low-profile compactness and improved performance, the proposed single-layered LWA is a promising candidate for 60 GHz V-band millimeter (mm)-wave applications.

DOA Estimation Based on ESPRIT Algorithm Method for Frequency Scanning LWA

In this paper, an improved estimation of signal parameters via rotational invariance techniques (ESPRIT) algorithm is proposed. As to the frequency scanning leaky wave antenna (LWA), the direction of arrival (DOA) can be effectively estimated by the algorithm. Compared with ESPRIT algorithm based on array antennas or electronically controlled beam scanning LWA, the ESPRIT algorithm using frequency scanning LWA obviously simplifies the hardware implementation. Furthermore, the wideband DOA can be simultaneously estimated by this proposed algorithm. The simulation results show that the estimated DOA results are in good agreement with the predicted angles, with root mean square error (RMSE) less than 1.6% on 38% relative bandwidth (ultra wide band).

Wide-Angle Frequency Scanning Leaky Wave Antenna Loaded CSRR Patch Based on SSPP Transmission Line

A novel composite left-and-right-composite-handed leaky wave antenna is proposed based on Spoof Surface Plasmon Polaritons slow-wave transmission line at microwave band in this paper. Wide-angle frequency scanning of the antenna is achieved by combining the slow-wave dispersion characteristics of Spoof Surface Plasmon Polaritons and the left-and-right-composite-handed characteristics of the complementary split ring resonator structure. The simulated and experimental results show that, with the increase of frequency, the radiation mode of the antenna gradually changed from slow-wave mode to fast-wave radiation mode, and the pattern changed continuously. The scanning region of the main beams proposed covers 110° in φ=0° plane when the frequency increases from 8GHz to 15GHz, and the gain of the antenna kept between 7dBi and 10.4dBi.

A Novel Frequency Scanning Leaky-Wave Antenna Based on Corrugated Substrate Integrated Waveguide

In order to facilitate the integration of active devices, a leaky-wave antenna (LWA) based on corrugated substrate integrated waveguide (CSIW) structure is proposed. By introducing rectangular ring slots on the CSIW structure, the proposed LWA is capable of beam scanning from backward to forward. The rectangular ring slots do not only enable energy leaking but also provide series capacitance. In addition, the grounded vias and quarter-wave open-circuit stubs provide shunt inductance. Thus, the proposed CSIW exhibits left-handed characteristic which enables beam scanning through the broadside. To further facilitate the design and suppress open-stopband of beam scanning antenna based on CSIW structure, an equivalent circuit model is developed and the relationships between structure parameters and the equivalent circuit parameters are presented. Based on this design guide, a leaky wave antenna is designed with radiation angle ranging from −53° to 23°. This proposed novel CSIW LWA has great potential in tunable or reconfigurable antenna design due to its ease of integration with active devices.

A HMSIW Circularly Polarized Leaky-Wave Antenna With Backward, Broadside, and Forward Radiation

A miniaturized frequency-scanning leaky-wave antenna (LWA) with circular polarization (CP) and backward-broadside-forward radiation is presented. Half-mode substrate integrated waveguide (HMSIW) in combination with interdigital capacitors (IDCs) is utilized in order to achieve a composite right/left-handed leaky-wave structure. Ramp-shaped slots are introduced as interdigital capacitors. Using this structure, the balanced condition (in which series and shunt resonances are equal) can be obtained for the unit-cell. As a result, wide bandwidth of 7.4-13.5 GHz with continuous angular scanning of ~ -70 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">°</sup> to 70 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">°</sup> is achieved. The axial ratio in the direction of the main beam is lower than 3.1. The performance of the antenna is measured, and close agreement between the simulation and measurement is observed.

K-Band Frequency-Scanned Leaky-Wave Antenna Based on Composite Right/Left-Handed Transmission Lines

A frequency-scanned leaky-wave antenna at K-band is proposed, which is based on two composite right/left-handed (CRLH) transmission lines with a virtual ground in between and composed of two identical RT 5880 substrates. The main beam of the proposed leaky-wave antenna scans from -25 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">°</sup> to +50 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">°</sup> , i.e., from backfire to endfire, as the frequency varies from 20 to 30 GHz. The highest antenna gain reaches 14 dB at a backfire direction. The proposed antenna has no vias. Its dimensions are 155 × 34 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> .

Leaky-wave antenna with arbitrary scan in the frequency band

A wide-angle frequency-scanned leaky-wave antenna design is presented. The proposed antenna operates in the nonfundamental mode and uses a meandered feed line to produce the exact phase-delay relationship necessary for achieving the desired scan in the specified frequency band. Experimental results obtained for a four-element antenna designed for the 6.05 – 6.75 GHz frequency band, show a low-loss scanned radiation pattern in the range of ± 45°. The measured gain is 5.75 ± 0.5 dBi. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52:2441–2444, 2010; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25496

Dielectric-Resonator-Based Composite Right/Left-Handed Transmission Lines and Their Application to Leaky Wave Antenna

Propagation and radiation characteristics of 1-D dielectric-resonator-based composite right/left-handed metamaterial structures with open mesh plates are investigated as a function of configuration parameters. The complex effective permittivity and permeability are estimated from the scattering parameters of the unit-cell structure. Based on this configuration, the single-mode transmission line is designed and the backfire-to-endfire frequency-scanned leaky wave antenna is implemented. It is found from numerical simulations that the 30-cell leaky wave antenna has a gain of 10 dBi with a scanning angle of over 90deg covering backfire-to-endfire directions. The measurement results show as wide beam-steering angles as numerically predicted.

Experiment on an aperture-coupled leaky-wave antenna with a pencil beam

A frequency-scanning leaky-wave antenna with an aperture-coupled feeding structure is presented. The aperture-fed structure is used to excite the microstrip first higher mode. In order to suppress the dominant mode, we add a sequence of covered wire in the center of this antenna. The measured H-plane main beam is a pencil beam, and is continuously scanned 12° as the frequency varies from 9.85 to 10.27 GHz. This feeding structure is very suitable for active phase antenna array applications. ©1999 John Wiley & Sons, Inc. Microwave Opt Technol Lett 21: 5–8, 1999.

An asymmetric feeding X-band active frequency-scanning leaky-wave antenna

An asymmetric feeding X-band active leaky-wave antennas is developed, to excite the first high order mode of the microstrip leaky wave antenna. One is the asymmetric feeding leaky-wave antenna which integrated with a HEMT oscillator, and the other is the frequency-tuned leaky-wave antenna which integrated with a varactortuned HEMT VCO. The microstrip leaky-wave antenna is operated in the first higher mode. To excite the first higher mode, the microstrip leaky-wave antenna is fed asymmetrically. The dominant mode excitation has been successfully suppressed by adding a sequence of covered wire in the center of the microstrip leaky wave antenna. The design of these active leaky-wave antennas is discussed and the beam scanning phenomena of the antenna is presented. The HEMT oscillator frequency is controlled by tuning the varactor DC bias and the beam scanning is demonstrated. The measured scanning angle agree with prediction, it is close to 30°as the VCO frequency tuned from 8.06 GHz to 9GHz.