Coplanar Waveguide-fed Antenna Research Articles

Electrohydrodynamic lithography of metallic mesh for optically transparent flexible and conformal antennas

The optically transparent antenna is becoming a very attractive proposition for various applications, such as wearable devices and vehicle radars. The fabrication of transparent flexible/conformal antennas is a long-lasting interest in academia and industry. However, the preparation of radio-frequency radiators with excellent conductivity and optical transmittance is still quite challenging. Herein, we introduce a facile approach to directly fabricate optically transparent flexible and conformal coplanar waveguide-fed antennas using programmable electrohydrodynamic lithography. Metallic meshes with transmittance above 90% have been successfully created based on the conformal electrohydrodynamic printing of high-viscosity photoresist masks, and the corresponding sheet resistance can be tuned down to ∼2 Ω/□. Then, the geometrical structure of the proposed transparent antenna has been systematically optimized because of the basic radio frequency components, including the radiator, feeder line, ground plane, and size of metallic meshes. Optically transparent flexible and conformal antennas are finally obtained, presenting an optical transmittance of 92% and 55%, respectively. The simulated and measured results demonstrate that the transparent antennas with a good optoelectronic performance indeed exhibit a nice electromagnetic behavior. We believe that this newly developed conformal electrohydrodynamic lithography method can be utilized to fabricate a variety of other transparent electronic devices, such as transparent electromagnetic shielding meshes on aircraft canopies, in the future.

High Gain Compact Multiband Cavity-Backed SIW and Metamaterial Unit Cells with CPW Feed Antenna for S, and Ku Band Applications

A compact multiband cavity-backed substrate integrated waveguide (SIW) and metamaterial antenna with coplanar waveguide (CPW) feed is designed for S and Ku bands thereby providing low and high frequency applications. Designing simultaneous achievement of high gain in S band and Ku band antennas are challenging task, but the proposed antenna overcomes this limitation. The proposed antenna has a ground structure with radiating T-shaped stub opposite to the feed line and a combination of SIW and metamaterial. SIW and complementary square split ring resonator (CSSRR) are used to enhance efficiency, directivity, gain and bandwidth. The proposed antenna structure uses FR-4 epoxy as the substrate material with Ɛr = 4.4 with a dimension of 40 × 40 × 1.6 mm and analyzed using ANSYS HFSS. The designed antenna resonates at three frequencies (i.e.), 4.23, 13.63 and 17.05 GHz with a gain greater than 5 dBi and efficiency greater than 80%. It is suitable for S band (ISM, WLAN, WiMax) and Ku band (radar, satellite communications) applications. The designed antenna is linearly polarized with high gain and efficiency at both the bands.

Reducing the radar cross section while maintaining the performance of a coplanar waveguide-fed antenna with an absorptive metasurface

The paper presents, for the first time, an analysis of the optimum arrangement of a coplanar waveguide-fed monopole antenna and a metasurface absorber (MSA), aiming to reduce the antenna’s in-band radar cross section (RCS) without perturbing its radiation properties. The proposed arrangement will show that the efficiency of the antenna, of great interest in many applications (such as the internet of things), can be preserved, contrary to results of previous papers focused on combining these structures. Moreover, the final structure will be easily embeddable (with an optimum number of unit-cells) as well as conformable. A proper analysis of the losses and currents on the structure will be provided for a better understanding of the interaction phenomena that arise. Good agreement between simulation and measurement results can be observed, corroborating the proper performance of the structure. Furthermore, bistatic reductionis obtained as well as monostatic RCS reduction, due to the angular stability of the employed MSA. Finally, it will be shown that the introduction of loaded resistors will be preferable to the use of a lossy dielectric to improve the RCS reduction whilst maintaining the antenna performance.

A Compact High-Gain Coplanar Waveguide-Fed Antenna for Military RADAR Applications

This paper presents a new design of a compact, high-gain coplanar waveguide-fed antenna and proposes a multielement approach to attain enhanced characteristics. The proposed method overcomes the simulation and geometrical complexity and achieves optimal performance features. The antenna prototype is carefully designed, and simulation results have been analyzed. The proposed antenna was fabricated on a new WangLing TP-2 laminate with dimensions (0.195λ × 0.163λ × 0.0052λ) at the lowest resonance of 9.78 GHz. The results have been tested and experimentally verified. The antenna model achieved excellent performance including a peak realized gain better than 9.0 dBi, optimal radiation efficiency better than 87.6% over the operating band, and a good relative bandwidth of 11.48% at 10 dB return loss. Symmetrical stable far-field radiation pattern in orthogonal planes and strong distribution of current are observed. Moreover, a comparative analysis with state-of-the-artwork is presented. The measured and simulation result shows a good agreement. The high-performance antenna results reveal that the proposed model is a good contender of military airborne, land, and naval radar applications.

A compact dual band-notched SWB antenna with high bandwidth dimension ratio

AbstractIn this research, a compact dual band-notched (DBN) super-wideband (SWB) coplanar waveguide-fed antenna with high bandwidth (BW) dimension ratio of 7427.4 has been presented. The proposed antenna covers a very wide frequency range from 2.8 to 40 GHz (BW ratio of 14.28:1) with |S11|<−10 dB. The overall antenna size is 20 × 14 × 1.6 mm3 which consists of an FR4 substrate with a dielectric constant of 4.4, a shovel-shaped radiating patch and the symmetric stair-shaped ground plane. The DBN characteristics are achieved by employing a pair of C-shaped and circular slots on its shovel-shaped radiating patch to reject the interferences caused by two WiMAX (3.7–4.7 GHz) and WLAN (5.7–6.4 GHz) bands. The notched frequency bands can be controlled by changing the radii of slots. The SWB property of the antenna is obtained by using a symmetric stair-shaped ground plane and also a shovel-shaped radiating patch. The measured results of the fabricated prototype in frequency-and time-domain are also presented and compared with the numerical results. The results indicate that the antenna has good performance over the entire operating BW (173.8%) which makes it very potential candidate for modern SWB applications.

A comparative performance analysis of various shapes and substrate materials loaded coplanar waveguide-fed antennas

The performance evaluation of coplanar waveguide (CPW)-fed square slot antenna which is loaded on various substrate materials is presented in this paper. The broadband antenna is printed on single-layer different PCB materials with change in permittivity of the substrate materials on the proposed model. The various substrate materials with relative permittivity of (εr) 2.2 (RT duroid), 3.2 (Arlon), 4.3 (FR4), and 9.8 (Alumina) are employed to produce the resonant frequency at 3.2, 3.0, 2.8 and 2.2 GHz, respectively which covers communication systems operating at RF bands applications. The proposed design has a return loss of less than −10 dB and VSWR < 2 in the desired band of operation with good radiation characteristics, gain and has attained the prescribed bandwidth. The parametric analysis of antenna has been performed using various substrate materials of different permittivity and its dimensions are optimized to ensure required characteristic in this work.

Design of a Graphene based Miniaturized CPW Fed Antenna for Terahertz Applications

The Terahertz frequency range is of importance for next generation wireless communication applications. In this paper a graphene based CPW feed antenna is designed and simulated for Terahertz applications. The designed antenna comprises of a Graphene patch over a silica substrate. Coplanar Waveguide (CPW) feed is used in this design to reduce the losses. This antenna is designed using High Frequency Structural Simulator (HFSS 11.1) software. Different performance parameters such as return loss, bandwidth, radiation efficiency and radiation patterns are extracted using simulation. The designed antenna resonates at 2.1 THz with a bandwidth of 200 GHz. Further, a modification is done in the radiating patch structure to achieve dual band response with wide bandwidth. The modified antenna resonates at 1.7 THz and 4.1 THz. This antenna produces 500 GHz and 520 GHz bandwidth at 1.7 THz and 4.1 THz respectively. A comparative study is also performed to find the most suitable substrate material for graphene patch antenna. For this study, different substrate materials such as Al2O3, BN, Quartz, Si3N4 and silicon dioxide are chosen.

CPW-fed triple high rejection notched UWB and X-band antenna on silicon for imaging and wireless applications

ABSTRACTIn this article, compact coplanar waveguide feed antenna covering ultra-wideband and X-band signals (2.98–13.34 GHz) is presented. Antenna also offers triple-notched band elimination (Wireless Interoperability for Microwave Access: 3.40–3.95 GHz, Wireless Local Area Network: 4.50–6.34 GHz and Downlink Satellite System: 7.11–7.802 GHz) which is due to insertion of stub and etching of slots. Antenna is fabricated and characterised on silicon for imaging and wireless applications having a fractional bandwidth of 133%. The antenna offers gain, radiation efficiency and group delay between 3.26 and 8.00 dBi, 84% and 92% and ≤±1.0 ns, respectively, for the entire bandwidth. Isolation of antenna in face-to-face and side-to-side orientations is <−25 dB with very less distortion presented in the transmission and reception of the signal. The radiations emitted by the antenna are observed as a dipole-like pattern in E-plane and omnidirectional in H-plane.

A new compact and miniaturized multiband uniplanar CPW-fed Monopole antenna with T-slot inverted for multiple wireless applications

In this paper, the design of a new compact uniplanar coplanar waveguide-fed antenna for multiband wireless application is presented and investigated. This antenna has a compact size of 25 × 25 mm2 and consists of a three parallel stub optimized added on rectangular slot to the radiator patch and T-shaped which inverted in the ground plane. The final prototype antenna designing resonantes at frequency bands (2.4–2.9 GHz), (3.7–5.2 GHz), and (5.7–6 GHz) with a return loss less than −10 dB. Details of the antenna configuration, design, simulation, and experimental results are presented, investigated, and discussed. The compactness, simple feeding technique, and conception of the uniplanar design make it easy to be integrated within devices of multiples wireless applications.

Novel compact UWB antenna with reconfigurable dual-band notches using pin diode switches actuated without λg /4 DC bias lines

This article presents a simple and compact ultrawideband (UWB) microstrip antenna whose band limited notches can be dynamically reconfigured individually to circumvent the problem of interference encountered between UWB and WiMAX/WLAN systems. The coplanar waveguide-fed antenna includes a defected ground structure (DGS) that generates the desired notch bands at the two aforementioned service bands. PIN diodes integrated within the DGS are used to electronically control the individual band limited notches without affecting each other's characteristics and the antenna's overall performance. The proposed technique offers the solution to the problem encountered in existing reconfigurable antennas which serve only one frequency band at a time. Furthermore, the proposed antenna use PIN diodes that do not need any dc bias line etched on the dielectric substrate, and thereby avoiding the problems associated with dc effects. Details of the antenna's design and simulation results are presented and validated with practical measurements. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:2392–2397, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27066

Broadband and Dual-Band Coplanar Folded-Slot Antennas (CFSAs) [Antenna Designer's Notebook

This paper presents a unified design methodology for dual-band and broadband coplanar folded-slot antennas (CFSAs). The design is achieved by using a coplanar waveguide-fed antenna element that is asymmetric with respect to the folded slot, and by adjusting the length of the stub inside the slot. A mathematical derivation, based on a transmission-line model for the asymmetrically-fed coplanar folded-slot antenna, is used on a single-frequency coplanar folded-slot antenna to determine the condition for a second resonance. In this way, when the second resonant frequency is close to the first, broadband uniplanar antennas with ~30%, bandwidth can be designed. In addition, at the dual-band mode, a frequency ratio (f <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> /f <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> ) of the order of 2.5 or more can be obtained. The effect of the ratio of the feed-shift distance to the length of the stub on the bandwidth is an important parameter, and is shown for both the broadband and dual-band designs. The presented method and tables are simple to use, provide very accurate results, and correctly predict the resonant frequencies for the dual-band coplanar folded-slot antennas. The theoretical and simulated results were verified by measurements of fabricated prototypes. The design guidelines cover a broad range of applications in the 2.4 GHz to 5.25 GHz range, with various bands and bandwidths.

Miniaturised coplanar waveguide-fed antenna and band-notched design for ultra-wideband applications

A miniaturised coplanar waveguide-fed ultra-wideband (UWB) antenna is presented here. The wideband operation is obtained through an optimised curvature of the radiating element. The input impedance of the antenna is matched using an elliptically tapered coplanar waveguide line. A high-band rejection characteristic at wireless local area network frequencies is achieved by inserting an ω-shaped slot on the antenna surface. The frequency domain dispersion characteristic is studied by means of the antenna transfer function both numerically and experimentally. Time domain characteristic of the antenna is investigated in detail for both UWB single-band and multiband schemes. In order to efficiently characterise the antenna system for an arbitrary pulse source excitation, the pole/residue model of the antenna system transfer function is presented using the matrix-pencil method.

Dielectric and patch antenna characteristics of new high- Q (1 − x)(Al 1/2Ta 1/2)O 2− x(Mg 1/3Ta 2/3)O 2 (0 ≤ x ≤ 1.0) microwave ceramics

The microwave dielectric properties of (1− x)(Al 1/2Ta 1/2)O 2− x(Mg 1/3Ta 2/3)O 2 (AMT) (0≤ x≤1.0) ceramics and design of small coplanar waveguide fed antenna (CPWFA) have been investigated. As (Mg 1/3Ta 2/3)O 2 concentration increased, dielectric constant ( ε r) and quality factor ( Q) significantly increased and the temperature coefficient of resonant frequency ( τ f) changed from negative to positive value. The τ f of 0 ppm °C −1 was realized at x=0.65 and the Qf 0 value and ε r for this composition were 112 470 GHz and 26.1, respectively. A newly developed 0.35(Al 1/2Ta 1/2)O 2–0.65(Mg 1/3Ta 2/3)O 2 dielectric materials were used for 1.5 GHz band CPWFA design and fabrication. The size of the CPWFA can be reduced by using AMT ceramics with high dielectric constant, insetting slits into patch, and fabricating CPW feed line in the ground plane. The slits play roles in not only lowering a center frequency but also fine-tuning for the proposed CPWFA together with open stub of CPW feed line. The CPWFA with slits has the lower center frequency than the conventional CPWFA, which suggests that an antenna size can reduce as large as 16.3%. Experimental results of the fabricated device were in good agreement with the simulation.

Computer-aided design of small patch antenna using (Al, Mg)TaO2 ceramics

The microwave dielectric properties of \(\left( {1 - x} \right)\left( {Al_{1/2} Ta_{1/2} } \right)O_2 - x\left( {Mg_{1/3} Ta_{2/3} } \right)O_2\) (AMT) \(\left( {0 \leqslant x \leqslant 1.0} \right)\) ceramics and the design of small coplanar waveguide fed antenna (CPWFA) have been investigated. (\(\left( {Al_{1/2} Ta_{1/2} } \right)O_2\) and (\(\left( {Mg_{1/3} Ta_{2/3} } \right)O_2\) have orthorhombic and tetragonal structure, respectively. As (\(\left( {Mg_{1/3} Ta_{2/3} } \right)O_2\) concentration increased, AMT ceramics transformed into the tetragonal structure. Specimens having tetragonal single phase could be obtained above x=0.6. As (\(\left( {Mg_{1/3} Ta_{2/3} } \right)O_2\) concentration increased, the grain size, dielectric constant \(\varepsilon _r\) and quality factor (Q) significantly increased and the temperature coefficient of resonant frequency \(\tau _f\) changed from negative to positive. The \(\tau _f\) of \(0 ppm ^\circ C^{ - 1}\) was realized at x=0.65 and the Q · fO value and \(\varepsilon _f\) for this composition were 112 470 GHz and 26.1, respectively. Newly developed \(0.35\left( {Al_{1/2} Ta_{1/2} } \right)O_2 - 0.65\left( {Mg_{1/3} Ta_{2/3} } \right)O_2\)dielectric materials were used for 1.5 GHz band CPWFA design and fabrication. The size of the CPWFA can be reduced by using high dielectric constant AMT ceramics, insetting slits into the patch, and fabricating CPW feed line in the ground plane. The slits play a role in not only lowering a center frequency but also fine tuning for the proposed antenna together with the open stub of CPW feed line. The CPWFA with slits has a lower center frequency than the conventional CPWFA, which suggests that the antenna size can be reduced by as much as 16.3%. The structure simulations of the CPWFAs have been performed to obtain impedance matching and to investigate the effects of slits. Experimental results of the fabricated device were in good agreement with the simulation.