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(a) 3D HFSS model of the LWA unit cell, with CSRR etched on the ground plane. (b) 2D top layer layout and dimensions. (c) Bottom layer with ground plane and CSRR design. r 1 = 5 mm and r 2 = 4 mm. The gap g and the distance between the two rings are 0.5 mm.
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Composite Right-/Left-Handed (CRLH) Leaky-Wave Antennas (LWAs) are a class of radiating elements characterized by an electronically steerable radiation pattern. The design is comprised of a cascade of CRLH unit cells populated with varactor diodes. By varying the voltage across the varactor diodes, the antenna can steer its directional beam from br...
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Citations
... e optimization of the state transition for such antennas can be performed using genetic algorithms [13] to achieve a smooth transition among different defined states. A variety of pattern tunable antennas are reported based on different configurations, such as complementary split-ring resonators (CSRR) on the ground [14] and a very popular method of using microelectro-mechanical switches (MEMS) with coupling cells. Due to the increased interest in slot antennas for future wireless applications [15], they have also been presented in a frequency and pattern reconfigurable design [16]. ...
This paper presents a reconfigurable antenna operating in three modes at different frequency bands with pattern reconfiguration. Frequency and pattern reconfigurability are achieved using four PIN diodes. In particular, two diodes are mounted in the radiating part of the hexagon shape to perform the frequency reconfiguration of the antenna. The other two PIN diodes are connected with the inverted L-shaped and CPW ground by changing the main lobe beam steering to achieve the pattern reconfiguration. An antenna has been designed, fabricated, and numerically and experimentally assessed. The prototype of the antenna is fabricated on a commercially available FR-4 substrate of thickness 1.6 mm ( ε r = 4.3). Thus, the proposed antenna supports several 5G sub-6 GHz bands (3.1 GHz, 4.1 GHz, and 3.8 GHz), WiFi (2.45 GHz), as well as (7.8 GHz, 9.5 GHz) X-Band Satellite applications. The obtained results are quite promising. In particular, it is observed that the measured results are in close agreement with the simulation results, and the proposed (compact) antenna prototype can be a prospective candidate for future portable devices, sensor networks, and telecommunication applications.
... A periodic SIW structure based conformal LWA scan its beam from near backfire, backward endfire and through the broadside to the forward direction [59]. Many useful novel conformal leaky wave antenna (CLWA) on a convex surface for Ku Band application has been designed [60][61][62][63][64][65]. This type of designs ensures the increased efficiency and gain in the Kuband, along with better return loss curve in terms of its shape and trend [66]. ...
This paper aims to review the work of various researchers for an old and latest advancements on Leaky Wave Antenna (LWA) theory and design. In microwave engineering, the leaky waves had been the most emerging field of research in last few decades. The basis for LWA is a guiding structure that allows the propagation of wave along the length of the antenna structure, with the wave leaking continuously along the structure. This type of antenna is classified into two categories, namely one dimensional and two dimensional LWAs. These LWAs radiate generally at the end fire direction and broadside direction to achieve the maximum scan angle for the radiation beam and these LWAs are uniform, quasi-uniform and periodic. After reviewing the working principles and characteristics of LWAs, an essence of some recent developments of designs have been discussed. Past advances include LWA designs that can scan to the endfire, LWA designs that can scan through the broadside, LWA designs that are conformal to the surfaces, and LWA designs that are capable of power recycling or include active elements. This paper also include the most demanding and latest beam scanning structures, bull's eye structures, full and half mode SIW planar LWA structures and RCS microstrip LWA structures. Some of these novel designs are derived by the recent developments in the field of metamaterials. Some other important development of LWAs such as artificial surfaces, plasmonic leaky wave nano antennas, subdiffractive plasmonic leaky wave antennas and graphene leaky wave antenna also have been reviewed.
... Backward to forward beam-scanning capacity is easy to achieve by applying the composite right-/left-handed (CRLH) [6][7][8]. Unfortunately, CRLH leaky wave antenna design is highly, perhaps excessively, complex [9]. ...
A miniaturized periodic microstrip leaky wave antenna (MLWA) with shorting pins is proposed in this paper. The suggested antenna consists of a number of stubs that are periodically placed on the side of the transmission line, with the outside edges of the stubs being all integrated with shorting pins. In comparison with the whole-width stubs MLWA, the proposed antenna has an advantage of effective reduction in antenna size for the similar beam-scanning capability. A series of simple and effective equations were obtained to calculate the propagation constant and determine the operating band of the antenna. The consistency of the calculated and measured propagation constant confirms the validity of the parameter equations. As demonstrated by experimental results, the main beam scans electronically and continuously from 145° to 61° in the y - z plane as the operating frequency changes from 5.7 GHz to 11.7 GHz.
Substrate integrated waveguides (SIW) have gained substantial different kinds of researches, ranging from microwave to optical bands due to their extraordinary properties such as low losses, low costs, small footprints as well as integrating with other types of printed circuit boards (PCB). SIW structures can be utilized to obtain all these advantages readily compared to different kinds of technologies such as conventional waveguides, microstrip transmission lines, coplanar waveguides, etc. The study provides an overview of the conducted studies on the substrate integrated waveguide for (76) articles for the period from 2001 to 2019 with particular emphasis on using SIW technology to realize small footprint metamaterial antennas. The study includes previous research work done on a single antenna and array models using the SIW technique. Thus, the paper focuses only on usages of the SIW in miniaturization of antennas footprints as well as performance enhancement. Different inclusions of unit cells (i.e., slots, split ring resonator SRR, and Complementary-SRR (CSRR) have been integrated into the main body of the SIW to realize the metamaterial properties. Design, modeling, and implementation of the recent SIW components and devices are provided. 1. INTRODUCTION Since the emergence of the substrate integrated waveguide technology SIW, a lot of research efforts have been done exploiting this technology [1-3]. Utilizing PCB method to fabricate SIW components offered the opportunity to integrate SIW components into circuits with different types printed. The advantages of SIW are; low loss as in the conventional waveguides compared to other components made throughvarious technologies. It is easy to fabricateat low cost due tostandard PCBtechnology. The SIW transmission lines have efficiently confine signals propagating inside their structures,due to the enclosed structures. Thus, the SIW can mitigate the crosstalk occurring among the PCB components and transmission lines carrying RF signals. Before the SIW technology, vertical current probes and fin lines were used for transition from bulky waveguides to printed circuits [4-6]. To fully integrate the transition, building planar transmission lines and integrated waveguides on the same substrate is now possible. The large bandwidth is one of the attractive features of the SIW guide as it obeys the conventional rectangular waveguide design rules. Also, all possible propagation modes TEno of the rectangular waveguide can be present in the SIW guides. Hence, bandwidth of the first mode is larger than the conventional
