Compact wideband cavity-backed slot antenna

A wideband cavity-backed slot antenna operated in the ultra-high frequency （UHF） band is introduced. The antenna has a compact structure and low profile with the size ratio of the ground plane to the slot only 1.6：1. The measured impedance bandwidth of VSWR≤3 achieves 85.3%, covering a frequency range from 390 MHz to 970 MHz. The measured gain is about 5.5-7.5 dB.

CHARACTERISTICS OF CAVITY-BACKED NARROW SLOT ANTENNA IN A LOSSY MEDIUM

The characteristics of a cavity-backed using the moment method and Dyadic Green's funused to convert the double series of the elements inintegration middle value theorem and elliptic integr}the elements. Numerical results show the effects of tthe input impedance, which could be used in designing the Cavity-Backed Slot Antenna

Compact 5G Vivaldi Tapered Slot Filtering Antenna with Enhanced Bandwidth

Compact fifth-generation(5G)low-frequency band filtering antennas(filtennas)with stable directive radiation patterns,improved bandwidth(BW),and gain are designed,fabricated,and tested in this research.The proposed filtennas are achieved by combining the predesigned compact 5G(5.975–7.125 GHz)third-order uniform and non-uniform transmission line hairpin bandpass filters(UTL and NTL HPBFs)with the compact ultrawide band Vivaldi tapered slot antenna(UWB VTSA)in one module.The objective of this integration is to enhance the performance of 5.975–7.125GHz filtennas which will be suitable for modern mobile communication applications by exploiting the benefits of UWB VTSA.Based on NTL HPBF,more space is provided to add the direct current(DC)biassing circuits in cognitive radio networks(CRNs)for frequency reconfigurable applications.To overcome the mismatch between HPBFs and VTSA,detailed parametric studies are presented.Computer simulation technology(CST)software is used for the simulation in this study.Good measured S11 appeared to be<−13 and<−10.54 dB at 5.48–7.73 and 5.9–7.98GHz with peak realized gains of 6.37 and 6.27 dBi,for VTSA with UTL and NTL HPBFs,respectively which outperforms the predesigned filters.Validation is carried out by comparing the measured and simulated results.

Design and optimization of a cavity-backed spiral antenna for use in 6-12 GHz band

The design and optimization of a self-complementary two-arm Archimedean spiral antenna backed by an absorptive cavity were presented. Parametric studies on the proposed antenna structure were carried out by using CST MWS. Simulation results show that the proper choice of spiral turns and cavity depth can miniaturize the dimensions of the cavity-backed spiral antenna presented here. According to simulation results, prototype antennas operating in the 6 12 GHz band are fabricated and the dimension of the proposed cavity-backed spiral antenna is 22 mm (diameter)×15 mm (height). The performance of the proposed antenna was measured and compared with the simulation results. It is shown that the experimental results are consistent with the theoretical predictions and the suggested antenna is good enough to adapt for various wideband applications.

Ultra-wideband low radar cross-section metasurface and its application on waveguide slot antenna array

A novel approach devoted to achieving ultra-wideband radar cross section reduction（RCSR） of a waveguide slot antenna array（WGSAA） while maintaining its radiation performance is proposed. Three kinds of artificial magnetic conductors（AMCs） tiles consisting of three types of basic units resonant at different frequencies are designed and arranged in a novel quadruple-triangle-type configuration to create a composite planar metasurface. The proposed metasurface is characterized by low radar feature over an ultra-wideband based on the principle of phase cancellation. Both simulated and measured results demonstrate that after the composite metasurface is used to cover part of the antenna array, an ultrawideband RCSR involving in-band and out-of-band is achieved for co-and cross-polarized incident waves based on energy cancellation, while the radiation performance is well retained. The proposed method is simple, low-cost, and easy-tofabricate, providing a new method for ultra-wideband RCSR of an antenna array. Moreover, the method proposed in this paper can easily be applied to other antenna architectures.

Broadband printed antennas and dual-polarized microstrip and waveguide slot antenna arrays

In order to meet the urgent needs in wireless communications, microwave image synthetic aperture radars （SAR）, and electronic warfare systems, this dissertation studies several types of broadband dual-polarized planar antenna elements and arrays, and proposes a few of novel designs with experimental verification. The main accomplishments reported in the dissertation are as follows.

Design of continuous long slot leaky-wave antenna for millimeter wave application

A simple and efficient design scheme of the continuous long slot leaky-wave antenna is developed. The key steps involved in the scheme are summarized. First, the cut-off frequencies of slot waveguides with different slot offsets are obtained by 3D finite-difference time-domain （FDTD） method, Second, the attenuation function a^a is estimated by the aperture distribution, and the attenuation function αrs is determined by the slot radiation. Finally, the attenuation function αrs is combined with the attenuation function αrs by the coefficient K. And an example in Ka band is presented. Moreover, the return loss of the E-plane Tee-junction （ET） and the radiation pattern of leaky-wave antenna are simulated. The scheme is verified by comparing with the experimental result.

Plus Shape Slotted Fractal Antenna for Wireless Applications

Fractal antennas are characterized by space filling and self-similarity properties which results in considerable size reduction and multiband operation as compared to conventional microstrip antenna. This paper outlines a multiband antenna design based on fractal concepts. Fractal antennas show multiband behavior due to self-similarity in their structure. The plus shaped fractal antenna has been designed on a substrate of dielectric constant €r = 4.4 and thickness 1.6mm. The proposed antenna is characterized by a compact size and it is microstrip feed fractal patch of order 1/3. It is observed that the antenna is radiating at multiple resonant frequencies. The resonant frequency is reduced from 2.2 GHz to 900 MHz after I & II iterations respectively. Thus considerable size reduction of 81.77% & overall bandwidth of 12.92% are achieved. The proposed antenna is simulated using the method of moment based commercial software (IE3D) and it is found that simulated results are in good agreement with the experimental results.

A NOVEL WIDEBAND ANTENNA DESIGN USING U-SLOT

U-slot patch antennas with П-shaped feed slot are studied, and numerical results based on the FDTD method are presented. The effects of varying physical parameters are investigated with a goal of understanding the coupling among different resonators. It is found that the U-slot patch antenna can be designed to attain 50% impedance bandwidth as well as 30-40% gain bandwidth. By altering the sizes of U-slot and feed slot, the wideband characteristic can be changed into a duai-frequency char- acteristic.

A Novel Structure of Slot-Antenna Array for Producing Large-Area Planar Surface-Wave Plasmas

The principle of surface wave plasma discharge in a rectangular cavity is introduced and the distribution of the electromagnetic field within a rectangular waveguide is analysed. A novel structure of a slot antenna array is presented. In comparison with the traditional slotantenna, it is shown that the designed slot antenna array can excite effectively the surface wave coupling into the chamber, and generate a stable large-area high-density plasma. These results are useful for exploring the optimized design of the slot-antenna for surface wave plasmas.

On the Design of Plus Slotted Fractal Antenna Array

A new technique which is a combination of fractal antenna and array antenna is presented to design Plus Slotted Fractal Antenna Array (PSFAA) in this paper. PSFAA with corporate feed operates at 2.5 GHz frequency. PSFAA is designed on FR4 substrate material with permittivity 4.4 and height 1.6 mm. PSFAA is designed up to 2nd iteration. High Frequency Structure Simulator (HFSS) software is used for simulation of PSFAA. The proposed antenna array operates at three bands with five frequencies 2.5 GHz, 4.1 GHz, 6.9 GHz, 7.4 GHz and 8.2 GHz. Simulated Return losses results of proposed PSFAA are -22.15 dB, -19.44 dB, -25.21 dB, -10 dB, -12.45 dB at above frequencies respectively. It has a gain of 9.22 dB at resonant frequency 2.5 GHz whereas conventional antenna array has a gain of 5.15 dB at resonant frequency 2.5 GHz. Return losses and gain of PSFAA also improved from conventional antenna array at various resonant frequencies.

Millimeter wave dielectric loaded exponentially tapered slot antenna array using substrate integrated waveguide for gigabit wireless communications

A new and upcoming application is the use of 60 GHz antennas for high date rate point-to-point connections to serve Gigabit(Gi-Fi)w ireless communications.The design of M illimeter w ave(M m W)antennas has to cope w ith the unadorned influences of manufacturing tolerances and losses at 60 GHz.In this paper,the concept of Substrate Integrated Waveguide(SIW)and Exponentially Tapered Slot(ETS)antenna w ere used together to design a high gain,efficient planar dielectric loaded antenna for M m W Gi-Fi w ireless communications at 60 GHz.The SIW is used to feed the antenna and a dielectric is utilized in front of the antenna to increase the gain.The dielectric loaded ETS antenna and compact SIW feed w ere fabricated on a single substrate,resulting in low cost and easy fabrication.The antenna w ith elliptical shaped dielectric loaded w as fabricated using printed circuit board process.The measured gain of the single element antenna is 10.2 dB,w hile the radiation efficiency of 96.84%is obtained at 60 GHz.The Y-junction SIW pow er divider is used to form a 1×4 array structure.M easured gain of the 1×4 array antenna is 13.3 dB,w hile the measured radiation pattern and gain are almost constant w ithin the w ide bandw idth of the antenna.

Analysis and Deskgn of Radiated Element and Array for a Radial Line Slot Antenna

The double layered Radial Line Slot Antenna (RLSA) is a new type of antenna for Ku band Direct Broadcasting Satellite (DBS) reception. This paper presents the structure, aperture field distribution, gain and efficiency of the antenna, discusses parameters of slot pair structure and influences of aperture field distribution and suggests calculation of parameters of the slot pairs and the array structure and CAD design procedures.

Printed elliptical slot UWB antenna for dual-banded application

Based on the analysis of printed elliptical slot (PES) UWB antenna,a dual-banded PES antenna is designed for WLAN and UWB bands at 2.4 GHz.The design cooperates two important wireless commutation system antennas into one printed antenna.In the design,a circular slot structure is presented,which is suitable for the band ejection.Characteristics of the designed antenna are analyzed and key parameters,such as S11,S21 and VSWR are measured.E-field distribution of the surface is simulated and analyzed.

DESIGN OF CPW-FED ASYMMETRIC SLOT UWB ANTENNA FOR WIRELESS APPLICATION

A compact Ultra-WideBand(UWB) slot antenna is presented in this paper. The slot is modified rectangular in shape and asymmetrically cut in the ground plane. A hexagonal patch with two stepped CoPlanar Waveguide(CPW) feed is used to excite the slot. Wider impedance bandwidth is achieved due to the extra inductive reactance created by the asymmetric slot which neutralizes the capacitive reactance of the hexagonal patch. The measured impedance bandwidth of the proposed antenna is 11.85 GHz(2.9–14.75 GHz). The radiation patterns of the proposed antenna are obtained and found to be omni-directional in H-plane and bi-directional in E-plane.

Double U-Shaped Slots Loaded Stacked Patch Antenna for Multiband Operation

The design of a seven-band stacked patch antenna for the C, X and Ku band is presented. The antenna consists of an H-slot loaded fed patch, stacked with dual U-slot loaded rectangular patch to generate the seven frequency bands. The total size of the antenna is 39.25 × 29.25 mm2. The multiband stacked patch antenna is studied and designed using IE3D simulator. For verification of simulation results, the antenna is analyzed by circuit theory concept. The simulated return loss, radiation pattern and gain are presented. Simulated results show that the antenna can be designed to cover the frequency bands from (4.24 GHz to 4.50 GHz, 5.02 GHz to 5.25 GHz) in C-band application, (7.84 GHz to 8.23 GHz) in X-band and (12.16 GHz to 12.35 GHz, 14.25 GHz to 14.76 GHz, 15.25 GHz to 15.51 GHz, 17.52 GHz to 17.86 GHz) in Ku band applications. The bandwidths of each band of the proposed antenna are 5.9%, 4.5%, 4.83%, 2.36%, 3.53%, 1.68% and 1.91%. Similarly the gains of the proposed band are 2.80 dBi, 4.39 dBi, 4.54 dBi, 10.26 dBi, 8.36 dBi and 9.91 dBi, respectively.

Triple Notched Band Characteristics UWB Antenna Using C-Shaped Slots and Slot-Type Capacitively-Loaded Loop (CLL)

Ultra wide bands antennas with notched bands characteristics have recently been considered for efficient communication between devices. In this paper, a compact ultra-wideband antenna (UWB) for UWB applications with triple bandnotched characteristics is presented. The proposed antenna consists of a square patch with four truncated corners and a partial ground plane with a rectangular slit. The operation bandwidth of the designed antenna is from 2.66 GHz to more than 13.5 GHz. Band-notched characteristics of antenna to reject the frequency band of 3.18 - 3.59 GHz and 4.70 - 5.88 GHz, is realized by inserting two C-shaped slots in the patch, the third band of 9.54 - 12.22 GHz is achieved by slottype capacitively-loaded loop (CLL) inserted in the patch near the feed line. Details of the proposed antenna design and simulated results are presented and discussed.

Increasing Microstrip Patch Antenna Bandwidth by Inserting Ground Slots

Microstrip patch antenna (MPA) is widely implemented in different communication systems. One of the main disadvantages of MPA which limits its applications is its narrow bandwidth. In this paper I enhanced the bandwidth of MPA by inserting multiple slots in its ground plane. I used FR-4 substrate to design this antenna. The dimensions of this antenna are 59 mm and 79 mm. The dielectric constant is 4.4 and the height is 1.6 mm. I inserted up to 15 slots in ground plane with 1mm width. The spacing between slots is 3 mm. I investigated two designs. In the first design, slots were arranged in parallel to the feeding line. In the second one, slots were arranged horizontally to the feeding line. The main objective of this paper is to design and simulate MPA suitable for wide number of applications. Antenna bandwidth improvement is 18%. All the simulations were obtained by using HFSS simulator.

Substrate Integrated Waveguide Based Monopulse Slot Antenna Arrays for 60 GHz Applications

Monopulse slot antenna arrays based on substrate integrated waveguide （SIW） are proposed for the application of 60 GHz mono- pulse tracking systems in this paper. The sum-difference monopulse comparator can provide a high amplitude and phase balance over wide frequency band and no phase delay technique is required for the difference channel. Resonant slot antennas are adopted as the radiating elements since they can be integrated with the sum-difference monopulse comparator in a single layer with a compact size. Two monopulse arrays with 2× 4 and 4×4 slot elements are designed, fabricated, and measured. Measured results show that the proposed antenna arrays have wide bandwidth covering the unlicensed 60-GHz band. The peak sum beam gain is 13.85 dBi for the 2 ×4 element array and 16.24 dBi for the 4×4 element array. The peak difference beam gain is 11.20 dBi for the 2×4 element array and 12.11 dBi for the 4×4 element array and the maximum null depth can reach -40 dB.

Design and Implementation of Step-Constant Tapered Slot Antennas for UWB Application

This paper presents the analytical design and high performance of step-constant tapered slot antenna (STSA) for ultra-wideband application. The return loss, radiation pattern, antenna gain, and level of cross polarization of this antenna are presented and analyzed. Utilizing Rogers (RO3006) substrate having a relative permittivity of 6.15, the proposed antenna provides the ultra-wideband (UWB) from 3.1 GHz to 10.6 GHz. It is observed that the return loss and gain are increased with increasing the step size. It has been observed from the simulation results incorporating CST microwave studio commercial software version 2015, the optimum return loss, directivity and gain are ?43 dB, 10.52 dBi and 10.20 dB, respectively, for 15 step size. Therefore, the newly proposed antenna will be a decent candidate for ultra-wideband application.