A 42‐GHz Wideband Cavity‐Backed Slot Antenna with Thick Ground Plane

We investigate the characteristics of a wideband and high‐gain cavity‐backed slot antenna in terms of the reflection coefficients, radiation patterns, and gain. A cavity‐backed slot antenna structure includes baffles, reflectors, and thick ground planes. The measured gain and bandwidth of a 10‐dB return loss in a cavity‐backed 2 × 2 array slot antenna with h₁=2 mm, d = 2 mm are 15.5 dBi and nearly 27% respectively, at 42 GHz. Baffles and reflectors are used to increase antenna gain, thus reducing the coupling among the slots on the thick ground plane.     

Gain improvement of planar-printed broadband end-fire antenna

A broadband high-gain planar-printed end-fire antenna is presented for microwave imaging application. The proposed antenna consists of a conventional Vivaldi antenna (CVA) with slot edges (SEs) and a planar phase compensation lens (PCL). Taking into account the actual phase error along E-plane direction at antenna aperture, a more precise and detailed analysis for the printed antenna with PCL is carried out. The PCL with specific layout of rectangular patches is utilised to enhance antenna gain especially at high frequencies, while the SE technique is employed to further improve directivity at low frequencies. The final design combining PCL and SE develops an expected high-flat-gain Vivaldi antenna over the entire operating range. The CVA and the proposed antenna are fabricated and measured. The measured results agree with the simulated ones well. The proposed antenna provides a high gain of 10–11.7 dBi in the range, which corresponds to a gain increase of 0.9–3.2 dBi compared to the CVA.     

Development of wideband CPW-fed hexagon-shaped circularly polarized slot antenna for wireless-communications

A hexagonal shaped circularly polarized (CP) wideband slot antenna using multiple stubs has been proposed and investigated. A hexagonal slot is created in the ground plane with tapered sections improving the impedance matching. Two radiators are incorporated in the structure, which is responsible for generating orthogonal degenerate modes; hence, CP radiation is achieved for the proposed antenna. For enhancing the gain of antenna, one radiator is directly connected to feed line and another one embedded in the ground plane. An inverted L-shaped arm is inserted in the slot to enhance and tune the circular polarized behavior. The presented radiator have input reflection coefficient ranges from 5.67 to 8.50 GHz (39.97%) and axial ratio bandwidth (ARBW) of 5.60–8.50 GHz (41.13%). The proposed antenna provides overlapping bandwidths of 5.67–8.50 GHz (39.97%) having average gains of 5.25 dBi within the entire frequency bands. The presented antenna is exceptionally good for the application of mobile and satellite communications.     

Angled Split-Ring Artificial Magnetic Conductor for Gain Enhancement in Microstrip Patch Antenna for Wireless Applications

A multiband rectangular microstrip patch antenna integrated with angled split- ring artificial magnetic conducting (AMC) structure is proposed. In order to achieve high gain, directivity and radiation efficiency, an \(3\times 2\) array of proposed angled split-ring patches which has multiple in-phase reflection phase characteristics at S-band (2–4 GHz) is presented as a reflector. A rectangular microstrip patch antenna integrated with the proposed angled split-ring AMC is fabricated, tested and its parameters are compared with the microstrip patch antenna backed with a flat metal sheet, and microstrip patch antenna integrated with conventional split-ring AMC structure. The presence of high scattered field amplitude between the angled arms lead to improved radiation characteristics and make the antenna more suitable for real-time wireless applications. The antenna attains 2.138 dBi increment in gain and 1.87 dBi increment in directivity when it is backed with the proposed angled split-ring artificial magnetic conducting structure instead of a flat metal sheet. A good pact is obtained between the simulated and the measured results.     

基于互补分裂谐振环的十字缝隙贴片天线（英文）

A compact patch antenna is designed, which is with structures of cross-shape slot, Complementary Split Ring Resonator(CSRR), and loaded transmission line. To implement the compactness in size, these structures are etched on the ground plane, then the input impedance has been improved. The CSRR is employed to improve impedance matching between the source and radiation patch, and the cross-shape slot on the radiation patch is utilized to increase the bandwidth. The design is validated by compariso...     

Small EBG resonator high-gain antenna using in-phase highly-reflecting surface

A small EBG resonator antenna (1.62lambda₀times1.62times₀timeslambda₀/4 in size) with specially-located PEC sidewalls to close the resonant cavity is proposed to achieve maximum directivity. An in-phase highly-reflecting surface is installed a quarter-wavelength above the PEC ground plane. For this small EBG resonator antenna, 13.5 dBi measured directivity and 11 dBi peak gain are obtained at 11.6 GHz.     

Textured surface slot antenna with reduced radar cross-section

Provided is experimental verification that a textured surface slot antenna is capable of producing usable far-field radiation patterns with preferential radiation into the forward half-space, at better than -16 dB return loss. In addition, it is shown that the antenna when connected to a 50 Omega load yields a backscattered return of only -17 dB compared to a matched slot antenna constructed on a perfectly conducting (PEC) ground plane, which returns -3 dB. The gain of the textured slot antenna structure was measured to be 3.35 dBi at 4.77 GHz     

Fixed-Beam Frequency-Tunable Phase-Reversal Coplanar Stripline Antenna Array

A fixed-beam frequency-tunable coplanar stripline (CPS) antenna array using the phase reversal technique and varactor diodes tuning is presented. The antenna array is composed of plurality of half-wavelength CPS sections interconnected by phase reversing crossovers. These crossovers have two functions: they serve as the radiators (small dipoles) of the array and also provide their own required in-phase excitations for broadside radiation. Two microstrip-to-CPS transitions for excitation of the balanced input/output antenna array are implemented and compared. A six-element array is demonstrated theoretically and experimentally, with 9.3 dBi of gain for bidirectional radiation and 12.5 dBi of gain for unidirectional radiation using a back reflector. Moreover, shunt varactor diodes are incorporated along the CPS structure to achieve frequency tuning through a bias voltage control while broadside radiation patterns remain fixed. The return loss and the radiation patterns at several frequencies are presented, and up to 50% tuning range is obtained. The proposed antenna array is simple and uniplanar with small lateral size, high radiation efficiency and high directivity. In addition, it uses a very simple biasing circuit with high DC-RF isolation. Its balanced input/output makes it suitable for RF system integration and active integrated antenna design.     

Beam-Switching Antenna Based on Plane Dipole Structure

A novel method for designing a beam-switching antenna with the plane dipole is presented. The antenna is composed of double dipoles placed at the center of an active square structure that is divided in four equal sectors by metallic sheets. Metallic patches at the outside of the structure are used to enhance the radiation performance of the antenna. In each step, the diodes in one sector are on, whereas other diodes are off. The sector with off-state diodes defines the direction of the radiation pattern. An antenna model is designed on the substrate of FR4. The proposed antenna operates from 4.8 GHz to 5.5 GHz with gain of 6.3 dBi and F/B (front to back ratio) of 13.2 dBi when the operating frequency is 5.2 GHz. The antenna radiation pattern can be swept in the entire azimuth plane in four steps with a 3 dB beamwidth of 90. The results reveal that the antenna could be used in the base station of the wireless communication systems.     

Compact linear tapered slot antenna for UWB applications

A novel ultra-wideband (UWB) antenna consisting of a linear tapered slot in the ground plane and a microstrip to slotline transition is investigated. The antenna possesses a wide bandwidth from 2.95?14 GHz for |S₁₁| < - dB and shows stable radiation patterns with an average gain of 3 dBi throughout the band. Measured group delay and transmission characteristics indicate that the antenna has good pulse handling capabilities.     

Broadband circularly polarised hexagonal slot antenna excited by a tapered microstrip feeder

In this article, a broadband circularly polarised slot antenna fed by a single microstrip line is implemented. The proposed antenna is composed of an unequilateral hexagonal slot to implement circular polarisation and tapered microstrip feeding line to enhance the impedance bandwidth. A conducting reflector is also employed to enhance the antenna gain. The proposed antenna, 60 mm × 60 mm × 18.12 mm in size, was fabricated and tested. The measured??10 dB reflection bandwidth and 3 dB axial ratio bandwidth were 48.9% and 17%, respectively. The measured gain of the fabricated antenna ranged from 5.4 dBi to 6 dBi within an axial ratio bandwidth of 3 dB.     

Band-notched inverted-cone monopole antenna for compact UWB systems

A microstrip-fed planar ultra-wideband monopole antenna with bandnotch characteristics is proposed. The antenna size is compact (18 x 30 mm) and operates over an extremely wide band of 3-16 GHz. The proposed design consists of an inverted cone as the radiating patch and a tapered ground plane. Wideband matching is obtained by properly shaping the ground. A pair of symmetrically placed quarter wave slot resonators is embedded in the ground plane for rejecting the 5-6 GHz WLAN band. Results indicate a stable and omnidirectional radiation pattern with an average gain of 3 dBi and a sharp reduction in gain at notched frequencies. Moreover, measured group delay and transmission characteristics show excellent transient response.     

Broadband CPW-fed folded-slot monopole antenna for 5.8 GHz RFID application

A folded slot is introduced to expand the impedance bandwidth and miniaturise the size of a coplanar waveguide (CPW)-fed patch monopole antenna for radio frequency identification (RFID) applications. The designed antenna, which, including ground plane, is only 13 mm in height and 11 mm in width, can operate at the 5.8 GHz band with measured impedance bandwidth and average antenna gain of 30% and /spl ges/5 dBi, respectively, and also conical radiation patterns. These properties make the antenna suitable for RFID tags.     

Analysis of L-probe Proximity Fed Annular Ring Patch Antenna for Wireless Applications

In the present paper, annular ring patch antenna with L-probe feeding has been analyzed using modal expansion cavity model. The proposed antenna shows wide band and ultra wide band operation which depends on the position of L-probe feeding and position of the shorting pin. For the fundamental \(\hbox {TM}_{11}\) mode, the bandwidth and gain is found to be 38.85 % and 7.8 dBi while for higher order \(\hbox {TM}_{12}\) mode bandwidth is obtained 58.71 % with corresponding gain of 6.1 dBi. The effect of shorting pin on the proposed antenna is also studied and it is found that the radiating structure is more compact in nature and improves the bandwidth upto 47.37 % with 8.0 dBi gain. Further, the proposed antenna has broadside radiation pattern over the entire bandwidth. The theoretical results are compared with IE3D simulated results which are in good agreement.     

Gain enhancement of a circularly polarized equilateral-triangular microstrip antenna with a slotted ground plane

A novel circular polarization (CP) design of a single-feed equilateral-triangular microstrip antenna with enhanced antenna gain is presented. This CP design is obtained by placing three triangular slots at properly locations below the equilateral-triangular radiating patch in the ground plane. By adjusting one of the triangular slot's side lengths slightly longer than that of the others, two orthogonal near-degenerate resonant modes for CP radiation can be excited. Measured antenna gain in this study can easily be increased by 3.3 dBi (5.1 dBi versus 1.8 dBi), as compared to the same height, substrate material, operating frequency and radiating patch shape of a regular equilateral-triangular microstrip antenna without triangular slots in the ground plane. Prototype antenna is fabricated for experimental evaluation. Simulated and measured results are presented.     

Circularly polarized patch antenna with simultaneously wide frequency tuning range and high gain performance

A tunable circularly polarized square patch antenna with parasitic elements is designed for a wide frequency tuning range and high gain characteristics. The proposed antenna is constructed by one main patch and four semi-elliptic parasitic units. By loading four varactor diodes and adjusting their capacitance values, the tunable feature is performed to reallocate the corresponding working frequency. Moreover, the diagonal corners of the antenna are cut and loaded with varactor diodes, which provide the appropriate perturbation between the two orthogonality modes of the antenna, so as to ensure the circular polarization characteristic in the entire operating tuning band. The experimental results demonstrate that the reflection coefficient and axial ratio are less than −13 dB and 3 dB, respectively. The proposed antenna features a relatively wide continuously tuning range of 24% within 1.9-2.3 GHz and a stable gain of over 7 dBi with a radiation efficiency of above 85%.     

小型化八边形基片集成波导背腔缝隙天线

提出一款新颖的W波段八边形基片集成波导(SIW)背腔缝隙天线。相较传统的缝隙天线，具有体积小、易加工、Q值高、成本低等优点，且易于成阵。通过调节天线背腔缝隙的长度、宽度，以及SIW腔体的尺寸优化天线的辐射特性，通过电磁仿真软件HFSS对模型进行仿真优化，确定了天线的最优结构。仿真实验结果表明，所设计的天线相对带宽约4.5%，方向性优良，中心频率点谐振深度<-31 dB，天线最大增益达到5 dBi，满足设计要求，验证了设计的正确性。所设计的SIW背腔缝隙天线拓宽了数字通信的可用频谱，是一种新的尝试，可为以后的研究提供新的参考思路。     

Design of a Planar Ultrawideband Antenna With a New Band-Notch Structure

A novel planar ultrawideband (UWB) antenna with band-notched function. The antenna consists of a radiation patch that has an arc-shaped edge and a partially modified ground plane. The antenna that makes it different from the traditional monopole antenna is the modification in the shape of ground plane, including two bevel slots on the upper edge and two semicircle slots on the bottom edge of the ground plane. These slots improve the input impedance bandwidth and the high frequency radiation performance. With this design, the return loss is lower than 10 dB in 3.1-10.6 GHz frequency range and the radiation pattern is highly similar to the monopole antenna. By embedding a pair of T-shaped stubs inside an elliptical slot cut in the radiation patch, a notch around 5.5 GHz WLAN band is obtained. The average gain is lower than -18 dBi in the stopband, while the patterns and the gains at frequencies other than in the stopband are similar to that of the antenna without the band-notched function.     

Compact One-Sixth Mode Substrate Integrated Waveguide Based Antennas for Wireless Communication and Public Safety Systems

The authors have chosen a hexagonal SIW cavity and designed it to resonate at the fundamental TM₀₁ mode at 5.9 GHz. The cavity is then bisected along its diagonal to produce a semi-hexagonal half-mode substrate integrated waveguide antenna, having a center frequency of 5.57 GHz lying within IEEE 802.11a WLAN U-NII 2C band. The half-mode SIW antenna depicts a gain of 5.5 dBi. A furthermore division of the full mode parent hexagonal resonator into six equal parts, each an equilateral triangle, constitutes the one-sixth mode of the parent cavity. This one-sixth mode SIW antenna operates at the resonating frequency of 5.4 GHz unlicensed band producing a gain of 5.38 dBi and finds suitable application in wireless communication systems. The antenna is further miniaturized with the inclusion of double T-shaped slot. This miniaturized antenna resonating at 4.96 GHz with a gain of 4.99 dBi is very apt in its use for public safety systems in the IEEE 802.11j 4.9 GHz band. Each of the structures is studied parametrically in great detail and the antenna prototypes are fabricated on Arlon AD270 substrate. HFSS software is used to simulate and analyze all of the antenna parameters. The simulated and measured results tallied against are found to be in good agreement with each other.     

A compact quasi-self-complementary dual band notched UWB MIMO antenna with enhanced isolation using Hilbert fractal slot

A compact ultrawideband multiple input multiple output antenna with dual band notch characteristics is proposed. The design utilizes the property of quasi-self-complementary monopoles to achieve a bandwidth that ranges from 2.2 GHz to 11 GHz. The design has a compact size of 30 mm × 41 mm × 1.59 mm. Two quasi-self complementary half circular monopoles are symmetrically arranged to obtain MIMO antenna. Bandnotch characteristics are obtained by adding parasitic strips of Levy's Fractal shape near the feed line. A Hilbert Fractal shaped slot is etched in the ground plane to enhance the isolation (|S₂₁| < −20 dB) throughout the operational bandwidth. The measured and simulated radiation patterns are in good agreement and is found to be stable throughout the ultrawideband. Moreover, the measured peak gain is found to be 4 dBi.