Tapered Slot Antenna Elements Research Articles

Ultrabroadband Circularly Polarized Antenna Array Based on Microstrip to SIW Junction

This communication presents a circularly polarized (CP) antenna array with ultrabroadband characteristics and a high gain for millimeter-wave applications. The CP is achieved by arranging eight linearly polarized (LP) tapered slot antenna elements in a circular arrangement based on sequential rotation (SR) techniques. The hybrid structure takes advantage of microstrip line (MSL) compactness in the feeding network and the capabilities of the substrate integrated waveguide (SIW) in antenna element design. A new T-junction MSL-to-SIW transition with a wide range of coupling ratios is used to serve as a wide power divider in the compact SR-feeding network. A detailed parametric study is carried out to demonstrate the effects of the coupling mechanism between the two transmission lines and to find the optimal configuration for the elements of the proposed antenna array. A tradeoff is made between antenna coupling, phase deviation, and overall size to achieve a compact structure with robust performances. An eight-element antenna array prototype is fabricated through the PCB process with a size of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$57\times 48\times96$ </tex-math></inline-formula> mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> . Measured results show a 3 dB axial ratio bandwidth of about 49% over the entire 22.8–37.7 GHz range and a maximum gain of 18 dBi.

Wideband and Low Direct-Coupling Tapered Slot Antenna Using Electromagnetic Bandgap Structures

This paper proposes a wideband and low direct-coupling tapered slot antenna (TSA) using electromagnetic bandgap (EBG) structure. We name this antenna the EBG-TSA. In some near field imaging systems including ground penetrating radars, a number of TSAs are arranged into an array with very small spacing in order to realize high-resolution imaging without synthetic aperture processing. Then, the direct coupling among TSA elements is nonnegligible and harmful. In this paper, we show that the EBG structure is effective in reducing the direct coupling with its stopband, which prevents an electromagnetic wave from propagating in a specific frequency band. Our EBG-TSA reduces its direct coupling by 3 dB or more in a wide band. We also find that the tapered EBG structure area assists the radiation by guiding the fin current flow two-dimensionally along the tapered slot so that the boresight gain increases. The EBG structure contributes to both the direct coupling reduction and the boresight gain enhancement.

A Compact Single-Layer Q-Band Tapered Slot Antenna Array With Phase-Shifting Inductive Windows for Endfire Patterns

A wideband millimeter-wave (mmW) tapered slot antenna (TSA) array operating in the Q-band is reported, aiming at the upcoming fifth-generation wireless communications. The antenna element is comprised by a TSA with two arrays of comb-shaped slits symmetrically cut on the edges of the two fins, respectively, which enables a degree of miniaturization for the radiator. Importantly, the geometrical structures of adjacent elements are flipped such that the fins of two neighboring TSAs are electrically connected. A miniaturized T-shaped eight-way power divider based on substrate integrated waveguide (SIW) technology is used to feed the linear array, where adjacent output channels are out-of-phase. In order to compensate the phase errors caused by the conventional compact T-shaped eight-way power divider, a well-tuned matching circuit composed of two consecutive inductive windows embedded inside the SIW is employed behind each TSA element, resulting in an enhanced gain and a low sidelobe level over a wide bandwidth. A prototype of the proposed antenna is fabricated using standard printed circuit board process and characterized, showing a good agreement between measured results and simulation predictions. The fabricated antenna experimentally achieves an $S_{11} dB bandwidth of 13.0% (38.97–44.45 GHz), within which the gain is higher than 13.4 dBi and the sidelobe level is below −14.6 dB. Its directive endfire radiation patterns and wideband operation make it a suitable candidate for various mmW wireless communication systems.

SIW‐tapered slot antenna for broadband MIMO applications

A substrate-integrated waveguide (SIW) tapered slot antenna for broadband multiple-input-multiple-output (MIMO) applications is presented in this study. The proposed MIMO antenna consists of two broadband tapered slot antenna elements, two SIW structures for feeding and two microstrip-to-SIW transitions. Four circular openings are designed on both sides of the SIW to improve the antenna's performance. The slots are etched on the connection of SIW and tapered slot antenna to adjust the input impedance of the antenna. The SIW structure and the shorting pin are used to isolate the feed lines and elements. Simulated and measured results verify the performance of the antenna. It shows that the proposed antenna has a broad bandwidth of | S 11 | <; -10 dB and | S 12 | <; -17 dB from 8.0 to 15.0 GHz covering the X-band and the lower K u -band.

Low-Cost Wideband mm-Wave Phased Array Using the Piezoelectric Transducer for 5G Applications

This paper presents a 55–65 GHz 16-element beam-steering array with a low-cost piezoelectric transducer-controlled phase shifter employing a single printed circuit board substrate. An ultrawideband antipodal fermi tapered slot antenna element with sine corrugation is designed to achieve symmetric E- and H-plane radiation patterns. The array is fed with an amplitude taper wideband Y-junction power divider integrated with an electromagnetic bandgap structure surrounding the feeding network. The measured results show a wide impedance bandwidth of S11 < −10 dB covering the band 55–65 GHz. The array measured gain is around 20 dB with low radiation losses. The 60-GHz phased array’s wide BW coverage, high gain, low feeding network loss, low cost, and low profile should have wide applications in the development of ultrawideband millimeter-wave scanning systems for the fifth generation communication applications.

SIW‐fed Vivaldi antenna with beam steering capabilities

ABSTRACTA tapered slot antenna element capable of reconfiguring its beam direction is presented. As the basic element, a Vivaldi antenna fed by a substrate integrated waveguide is chosen. The Vivaldi antenna is complemented by a parasitic planar array of small metallic patches placed in front of its aperture and by corrugated edges of the Vivaldi antenna's arms to provide reconfiguration capabilities. The proposed antenna's beam can be steered in five directions by configuring the interconnections of the parasitic patches and by activation/deactivation of the corrugated edges in the antenna arms. The antenna steers the radiation beam over ±30° in E plane and operates in the frequency band of 6.0–6.5 GHz. The measured gain at 6.25 GHz for 0°, ±15°, and ±30° beam direction of the antenna with ideal switches, is 8.4 dBi, 7.5 dBi, and 6.7 dBi, respectively. © 2017 Wiley Periodicals, Inc. Microwave Opt Technol Lett 59:1022–1027, 2017

Circularly polarised MIMO tapered slot antenna array for C‐band application

A novel configuration of a multiple-input multiple-output (MIMO) circularly polarised (CP) antenna array operating in the C-band is presented. The array consists of 2 × 2 antipodal tapered slot antenna elements created in the sides of a rectangular as the rectangular grid that supplies a broadband impedance bandwidth and high gain array. To provide broadband MIMO with polarisation diversity, the antenna uses a dual-port feed network consisting of couplers, a crossover and delay lines which the diversity of polarisation changed by input ports.

Particle swarm optimization of the tapered slot antenna for wideband scanning E-plane linear array

Paper describes a novel way to optimize the unilateral tapered slot antenna (TSA) being an element of a wideband scanning E-plane linear array. Taper profile of the antenna is mathematically represented as a piecewise linear function. Particle swarm optimization algorithm is implemented to find the coordinates of piecewise linear profile following the purpose to minimize the active reflection coefficient of TSA in a scanning array environment. Active reflection coefficient down to −15 dB is theoretically achieved for TSA in E-plane linear array operating over the most part of frequency band 5–10 GHz and scanning sector ±30°. The proposed design approach is validated by experimental investigations of two linear array test samples with fixed main lobe directions at 0° and 30° respectively. Each test sample is composed from eight similar TSA elements with the optimized piecewise linear profile. Arrays are excited by the 8-way microstrip power divider of corporate type with microstrip true time delay lines at the outputs that provide required wideband phasing of radiating elements.

Propeller-Shaped Antenna: A Steerable Ultrawideband Planar Antenna

We propose an ultrawideband planar antenna having a controllable radiation pattern for coarse steering to avoid fading in indoor communications. In the antenna, multiple tapered-slot antenna (TSA) elements are connected to a feeding part through p-i-n diode switches. The TSA elements have such wide aperture and round shape that the mutual coupling among them is effectively suppressed, resulting in sufficient steering ability. Simulation and experiments demonstrate that the radiation is switched to intended directions. Reflection S <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sub> is below or around -10 dB in the frequency range of 3.1-10.6 GHz independent of the switching condition. Basic characteristics are investigated and discussed.

Novel Preprocessing Techniques for Accurate Microwave Imaging of Human Brain

Two novel preprocessing techniques are applied to reinforce the detection performance and the image quality in microwave imaging systems designed for brain stroke detection. The image of energy distribution is obtained by applying a delay-and-sum beamforming to the backscattered signals measured using a hemielliptical array of 16 corrugated tapered slot antenna elements surrounding the head. The beamformer forms a spatially filtered combination of time-delayed response of scattering points in the head exposed to microwave radiation over the band from 1 to 4 GHz. The proposed techniques are validated on a realistic head phantom that is fabricated to emulate the electrical properties of real human head. The results show how the proposed techniques enable the detection and localization of hemorrhagic stroke accurately.

Experimental investigations into detection of breast tumour using microwave system with planar array

A microwave imaging system for the potential detection of tumours in breast tissues using a planar array that employs 6×2 compact tapered slot antenna elements is reported. In this system, the breast is placed on a plastic sheet and slightly compressed to take a semi-rectangular shape; this allows for accurate image reconstruction using a planar array. Both the array and the phantom are immersed in a coupling medium to increase the signal penetration, and thus, the dynamic range of the system. In order to quantity the effect of changing the number of elements and their positions in the array, image reconstruction is undertaken with three different configurations. That is with 6- and 12-array elements and an additional 90° rotation of the phantom. To test the designed system a suitable combination of materials are used to fabricate a low-density, heterogeneous breast phantom. Two- and three-dimensional versions of a confocal imaging algorithm are used to construct the images and metrics are proposed to evaluate the quality of the image. Single and multiple embedded targets are shown to be resolved using the proposed array and imaging algorithm in either two or three dimensions.

360° scanning multi-beam antenna based on homogeneous ellipsoidal lens fed by circular array

Presented is a multi-beam antenna which can realise 360° switching scanning in azimuth. The antenna system is composed of a homogeneous ellipsoidal lens and a planar circular tapered slot antenna (TSA) array. Each TSA element is fed with a rectangular waveguide by a special waveguide-to-TSA transition. Beam scanning can be achieved by switching between the waveguide feeders. A Ku-band Teflon ellipsoidal lens fed with 20 Fermi-TSAs has been fabricated. Measurements show that the sidelobe levels of the 20 beams are all below-17 dB and the gain differences are all within +0.4 dB.

Analysis and design of wideband widescan planar tapered slot antenna array

Phased arrays have been required to operate over wide bandwidths and wide scan angle to support multifunction operation in both telecommunication and radar. In response to that need, this study firstly analyses the performance of the connected planar tapered slot antenna array and finds that the mutual coupling is essential and has good effect in wideband antenna array design. Then the authors design a wideband widescan planar tapered slot antenna array system with novel dual-parabola tapered slot antenna elements and feed network. This array can operate from 1.6 to 9 GHz and scan angle up to 45°. Both simulation and measurement results are shown to certificate the performance of the proposed antenna array.

Study and Design of a Differentially-Fed Tapered Slot Antenna Array

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> The results of a parametric study and design of an ultrawideband dual-polarized array of differentially-fed tapered slot antenna elements are presented. We examine arrays of bunny-ear antennas and discuss the capabilities and limitations of differential antenna technology. As we focus on radio astronomical applications, the absence of a balancing-feed circuit not only reduces the first-stage noise contribution associated to losses in the feed, but also leads to a cost reduction. Common-modes are supported by the antenna structure when a third conductor is present, such as a ground plane. We demonstrate that anomalies may occur in the differential-mode scan impedance. Knowledge of both types of scan impedances, differential and common mode, is required to properly design differential LNAs and to achieve optimal receiver sensitivity. A compromise solution is proposed based on the partial suppression of the undesired common-mode currents through a (low loss) balancing-dissipation technique. A fully steerable design up to 45<formula formulatype="inline"><tex Notation="TeX">$^{\circ}$</tex> </formula> in both principal planes is achieved. </para>

Design of compact broadband TSA arrays by using element mutual coupling

A compact broadband tapered slot antenna (TSA) array was designed, which can achieve a bandwidth of 4.5–18 GHz with scan angle up to 60°. Contrary to the conventional array design, the key to this design was taking advantage of mutual coupling between closely-spaced elements. A generic analytical-based method was developed to predict the mutual coupling between elements in the TSA array and the strong coupling between TSA elements was identified as being essential to the operation of arrays over broad bandwidth.

A K‐band inverted microstripline‐fed linear tapered slot antenna and its 16‐element E‐plane array

AbstractAn inverted microstripline‐fed linear tapered slot antenna element and a design of its 16‐element E‐plane array are presented in this paper. The element is designed using the finite‐difference time‐domain (FDTD) method. The calculated results show that it has a wide‐impedance bandwidth in the K‐band. To investigate the E‐plane array, the return loss at each element input port, the couplings among elements, and the array's radiation patterns are obtained using the FDTD method. Using a unique three‐piece assembled structure, the array is fabricated and tested experimentally. The measured results show that it has a wide bandwidth and antenna efficiency. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 45: 241–246, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20784

A K‐band suspended microstripline‐fed linear tapered slot antenna and its E‐plane arrays

AbstractA suspended microstripline‐fed linear tapered slot antenna element and its E‐plane linear arrays are presented in this paper. The element is studied and designed using the finite‐difference time‐domain (FDTD) method. The simulated results show that the element has a good antenna performance from 17 to 24 GHz. To build the E‐plane arrays, a unique five‐piece assembled structure which guarantees a uniform air‐filled thin substrate in the suspended microstrip line parallel feed‐network, has been developed. Four E‐plane arrays with different numbers of elements (4, 8, 16, and 32) are fabricated and their antenna gains and patterns are examined experimentally. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 41: 451–455, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20168

A linear tapered slot antenna electromagnetically coupled with perturbed coplanar waveguide

AbstractThis paper considers a linear tapered slot antenna element with electromagnetically coupled feed and discusses the matching and the radiation characteristics. In the proposed antenna element, the coplanar line with perturbed feeder, that is, the coplanar waveguide, is considered as a coupled slot line. Each line is short‐circuited to the ground conductor with different length. By electromagnetic coupling on the single‐sided coplanar dielectric substrate, feed to the linear tapered slot antenna element is realized. The following results are obtained. (1) It is possible to control the coupling magnitude and the matching frequency between the antenna element and the feeder. (2) An equivalent circuit is proposed for the matching characteristics, and the circuit parameters are determined. (3) The characteristics obtained by experiment and with an electromagnetic simulator are compared to the characteristics derived from the equivalent circuit. (4) The radiation directivity is of the single‐direction end‐fire type. A gain of 8.1 dBi and a cross polarization of −16 dB in the front direction are realized. On the basis of these results, it is demonstrated that the proposed antenna element is useful as a planar antenna element. © 2004 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 87(8): 13–23, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.10218