Millimeter-Wave Antenna of a Travelling-Wave Long Sinusoidal Slot in the Narrow Face of a Rectangular Waveguide

A travelling-wave long sinusoidal slot in the narrow face of a millimeter-wave (Ka-Band) rectangular waveguide is investigated. To the best of our knowledge, a slot of this shape is applied to the narrow face of a rectangular waveguide for the first time at this frequency range. The analytical study is based on the magnetic current model. Experimentally, far-field and S-parameters are measured and a good match is obtained between analytical and measured patterns. Frequency scan rates and velocity ratios of the structure are calculated. The effect of the sinusoidal slot’s geometrical parameters (amplitude, period and number of periods) on the radiation patterns is also investigated. The drawback of the sinusoidal radiator is its cross-polarized beam that is not convenient for antenna applications. These co and cross-polarized beams scan in two different angle regions. To filter/suppress the cross-polarized beam, a grid polarizer is mounted to the sinusoidal slot and a 15 dB suppression level is reached. S-parameters measurement shows that the antenna efficiency increases remarkably after the application of the grid polarizer to the slot.     

Broadband proximity fed ring microstrip antenna arrays

Various gap-coupled array configurations of ring microstrip antennas and rectangular slot cut ring microstrip antennas with proximity fed slot cut ring microstrip antenna for larger bandwidth and gain are proposed. The rectangular slot in ring patch reduces its orthogonal TM₀₁ and TM₀₂ mode resonance frequencies and along with TM₁₀ modes of fed and parasitic ring patches, yields broadband response. The gap-coupled configuration with ring patch and slot cut ring patch yields bandwidth of nearly 430 MHz with broadside radiation pattern and peak gain of more than 9 dBi. By gap-coupling ring patches along all the edges of proximity fed pair of slot cut ring patch, a 3 × 3 ring microstrip antenna array is realized. It yields bandwidth of more than 460 MHz with peak gain of more than 10 dBi. To further improve upon the bandwidth, a 3 × 3 array of ring patches in which rectangular slot is first cut on the edges of ring patch which are gap-coupled along x-axis and further cut inside the patches which are gap-coupled along x and diagonal axes, is proposed. Both of these configurations yield bandwidth of more than 500 MHz (>45%) with a peak gain of around 10 dBi.     

A wideband high gain dielectric resonator antenna for RF energy harvesting application

A novel high gain and broadband hybrid dielectric resonator antenna (DRA) is designed and experimentally validated. To obtain the wide impedance bandwidth, the proposed antenna geometry combines the dielectric resonator antenna and an underlying slot with a narrow rectangular notch, which effectively broadens the impedance bandwidth by merging the resonances of the slot and DRA. An inverted T-shaped feed line is used to excite both antennas, simultaneously. It supports amalgamation of different resonant modes of the both, DRA and slot antenna. The measured results show that the proposed antenna offers an impedance bandwidth of 120% from 1.67 to 6.7 GHz. The antenna gain is next enhanced by a reflector placed below the antenna at an optimum distance. On engineering the height and dimension of this reflector the antenna gain is improved from 2.2 dBi to 8.7 dBi at 1.7 GHz. Finally, antenna operation is attested experimentally with a rectifier circuit in the frequency range of 1.8–3.6 GHz, where various strong radio signals are freely available for RF energy harvesting. The measured maximum efficiency of the rectifier and rectenna circuit were found to be 74.4% and 61.4%, respectively.     

A novel single feed frequency and polarization reconfigurable microstrip patch antenna

In this paper, a novel single feed frequency and polarization reconfigurable microstrip patch antenna is presented. This antenna mainly comprises of a corner truncated square patch with a rectangular ring slot, eight PIN diodes and six conductive pads. Four PIN diodes are placed symmetrically in the rectangular ring slot to bridge the gap and to switch the frequency between WLAN bands resonating at 5.2G Hz and 5.8G Hz. Four PIN diodes connect the corner truncated square patch to parasitic triangular conductors. PIN diodes are used to switch the polarization between linear, right hand circular and left hand circular at each frequency. When compared to conventional patch, the proposed design provides a size reduction of 12% at 5.2G Hz, and 30% at 5.8G Hz. The simulated reflection coefficient and radiation patterns are presented and compared with the experimental data. This antenna finds applications for modern wireless communication system.     

Design and analysis of implantable CPW fed bowtie antenna for ISM band applications

A novel implantable coplanar waveguide (CPW) fed crossed bowtie antenna is proposed for short-range biomedical applications. The antenna is designed to resonate at 2.45 GHz, one of the industrial-scientific-medical (ISM) bands. It is investigated by use of the method of moments design equations and its simulation software (IE3D version 15). The size of the antenna is 371.8 mm³ (26 mm × 22 mm × 0.65 mm). The simulated and analyzed return losses are −23 and −25 dB at the resonant frequency of 2.45 GHz. We have analyzed some more performances of the proposed antenna and the results show that the proposed antenna is a perfect candidate for implantation. The proposed antenna has substantial merits like low profile, miniaturization, lower return loss and better impedance matching with high gain over other implanted antennas.     

Design of implantable CPW fed monopole H-slot antenna for 2.45 GHz ISM band applications

In this paper, the design and radiation performance of the novel miniature implantable coplanar waveguide fed H-slot antenna for embedded in human body operating in the ISM band frequency is proposed. A parametric model of a skin, fat and muscle implantable antenna is designed and a prototype is fabricated on biocompatible alumina ceramic substrate (ɛ_r = 9.8 and thickness = 0.65 mm) and it is tested. Antennas are further analyzed in inside a pork tissue and human body phantom liquid. Results indicate strong dependence of the exhibited radiation performance (radiation pattern, gain, specific absorption rate and quality of communication with exterior instruments) on design parameters and operating frequency. The proposed antenna design methodology can be applied to optimize antenna for several implantation scenarios and ISM band applications.     

A modified ground apollonian ultra wideband fractal antenna and its backscattering

This paper presents the design of a modified ground apollonian ultra wideband (UWB) fractal antenna. The printed fractal antenna has been designed on a substrate with dielectric constant ?_r = 4.3 and thickness h = 1.53 mm. The antenna has been fabricated with optimized dimension and tested. The experimental result of this antenna exhibits UWB characteristics from frequency range 3 GHz to 18 GHz. This corresponds to 142.86% impedance bandwidth with center frequency of 10.5 GHz. The experimental radiation patterns of this antenna are nearly omni-directional in H-plane and bidirectional in E-plane. The effect of various design parameters on UWB characteristics have also been analyzed using a 3D electromagnetic simulator based on FEM method. The simulated and experimental results are in good agreement. The backscattering RCS of this UWB fractal antenna is better than ?31 dB throughout the FCC band (3.1 GHz to 10.6 GHz). The proposed coplanar waveguide feed appollian fractal antenna can be easily integrated with radio-frequency/microwave circuitry with low-manufacturing cost and useful for UWB applications.     

A beam steering antenna for X-band high power applications

There is a considerable interest in the antennas which have high power handling capacity with beam steering functionality. The design of narrow side waveguide slot-array antenna for high power applications is introduced in this paper. An approach to achieve a uniform radiation slot waveguide antenna is presented. The large scale array antenna can be composed of such antenna cells. Moreover, it is possible to realize beam steering in the azimuth direction by adjusting the broad wall dimension of the waveguide. Besides, this slot waveguide antenna is expected to have high power handling capacity in vacuum environment, because there is no dielectric or electric field enhancement inside the antenna.     

Design of a compact U-shaped slot triple band antenna for WLAN/WiMAX applications

This article presents a small, low-profile planar microstrip antenna that is applicable for both WLAN and WiMAX applications. The goal of this paper is to design an antenna which can excite triple-band operation with appreciable impedance bandwidth to combine WLAN/WiMAX communication specifications simultaneously in one device. The designed antenna has a compact size of 10 × 26 mm². The proposed antenna consists of an inverted U-shaped slot radiator and a defected ground plane. Overall the design method and parametric study found appropriate dimensions, which provides three distinct bands I from 2.40 to 2.52, II from 3.40 to 3.60 and III from 5.00 to 6.00 GHz that covers entire WLAN (2.4/5.2/5.8 GHz) and WiMAX (2.5/3.5/5.5) bands. Finally, a prototype antenna was fabricated and experimentally characterized to verify the design concept as well as to validate the simulation results. Thus the simulation results along with the measurements show that the antenna can simultaneously operate over WLAN and WiMAX frequency bands.     

A new wideband planar antenna with band-notch functionality at GPS,Bluetooth and WiFi bands for integration in portable wireless systems

Empirical results are presented for a novel miniature planar antenna that operates over a wide bandwidth (500 MHz to 3.05G Hz). The antenna consists of dual-square radiating patches separated by two narrow vertical stubs to reject interferences from GPS, Bluetooth and WiFi bands. Radiating patches and stubs are surrounded by a ground-plane conductor, and the antenna is fed through a common coplanar waveguide transmission line (CPW-TL). The two vertical stubs generate pass-band resonances enabling wideband operation across the following communications standards: cellular, APMS, JCDMA, GSM, DCS, PCS, KPCS, IMT-2000, WCDMA, UMTS and WiMAX. Embedded in the ground-plane conductor is an H-shaped dielectric slit, which has been rotated by 90°, whose function is to reject interferences from GPS, Bluetooth and WiFi bands. Measurements results confirm the antenna exhibits notched characteristics at frequency bands of GPS (1574.4–1576.4 MHz), Bluetooth (2402–2480 MHz) and WiFi (2412–2483.5 MHz). The impedance bandwidth of the antenna is 2.55G Hz for VSWR < 2, which corresponds to a fractional bandwidth of 143.66%. Measured results also confirm that the antenna radiates omnidirectionally in the E-plane with appreciable gain performance over its operating frequency range. The antenna has dimensions of 15 × 15 × 0.8 mm³.     

基于T型谐振器的抗干扰矩形波导缝隙阵列天线设计

介绍了一种抗干扰矩形波导缝隙阵列天线的设计方法,仿真、设计并加工了一款基于T型谐振器的四缝隙矩形波导缝隙阵列天线. 通过在矩形波导下壁引入周期性的T型谐振器,有效提升了天线的抗干扰能力. 测试结果表明,该天线的?10 dB阻抗带宽为10.3%（5.5～6.1 GHz）,增益为11.5～12.8 dBi,天线效率为72.1%～87.3%。与传统矩形波导缝隙阵列天线相比较,本文设计天线在抑制频段 7.9～9.6 GHz的抗干扰能力提升了32.2～69.3 dB,适用于多频段、多任务的无线通信、雷达系统等.     

Design of a novel bandwidth-enhanced double-slot TSA and analysis according to the microwave network theory

In this paper, a novel bandwidth-enhanced ultra-wideband (UWB) tapered slot antenna with Y-shaped corrugated edges, is proposed. In the double-slot structure, the two slots are separated by a V-shaped metal surface with straight edges, which is beneficial to improve the directivity of the antenna. Meanwhile, an exponential Y-shaped corrugated edge is designed. This novel corrugated edge can not only improve the impedance bandwidth, but also enhance the gain of the antenna. Additionally, according to the theory of microwave network, this paper analyzes the reason of bandwidth enhancement realized by double-slot structure. The proposed antenna provides 167% fractional bandwidth from 2.5 GHz to 28 GHz. The gain of the proposed antenna is more than 10 dB from 3.5 GHz to 25 GHz, and more than 8 dB at the whole operating band.     

Research on dual-polarized circular waveguide antenna fed by L-shaped probes

This paper researched a kind of dual-polarized and cylindrical waveguide antenna fed by two L-shaped probes at the antenna bottom. The designed antenna was composed of two orthogonal L-shaped coaxial probes and a cylindrical waveguide cavity. The two orthogonal field structures were excited and the dual-polarized radiation mode was formed. The feeding cables of two polarization ports went through the bottom of the cylindrical cavity and were connected with the microwave adaptors. The bottom feeding structure was suitable to constitute a planar antenna array. The electromagnetic simulation and optimization design of the proposed antenna were carried out by using the full wave electromagnetic simulation technique, and the simulation results showed that the isolation between two polarization ports were more than 20 dB within the frequency range of 4.8–5.4 GHz. At the center frequency, the cross-polarization levels of radiation pattern were lower than −21 dB at the boresights and the beam width of radiation patterns at E-plane and H-plane were more than 70° for two polarization ports. The designed antenna in this paper was fabricated and measured. The measurement results indicated that the designed antenna achieved anticipated radiation performances and design effectiveness of the dual-polarized antenna in this paper was proved. The dual-polarized and cylindrical waveguide antenna is suitable for some application fields such as dual-polarized array radar. The research results in this paper can provide a technical basis for the practical engineering application.     

Time domain analysis for foldable thin UWB monopole antenna

In this paper, the time domain analysis of an Ultra Wide Band antenna flexible circular monopole antenna is presented. The antenna is fabricated on liquid crystalline polymer flexible substrate with a compact geometry that makes it suitable for wearable applications under different bending conditions. The antenna is fed by coplanar waveguide transmission line and has a compact total size of 40 × 22 mm². Moreover, the antenna has good radiation efficiency (97%) over the bandwidth. The presented antenna has a good performance over the operating spectrum for straight and bending configurations. The design principals along with simulation and experimental results are presented in this contribution.     

Multiband monopole antenna loaded with Complementary Split Ring Resonator and C-shaped slots

This paper presents a compact semi circular monopole antenna loaded with Complementary Split Ring Resonator (CSRR) and two C-shaped slots is proposed for Global System for Mobile Communication (GSM), Worldwide Interoperability for Microwave Access (WiMAX) and C-band applications. The size of the proposed antenna is 20 × 20 × 0.5 mm³. The resonance frequency of WiMAX (3.73 GHz) is achieved by introducing CSRR slots on the ground plane. To realize multiband characteristics for GSM (1.77 GHz), WiMAX (2.6 GHz) and C-band (4.15 GHz), two C-shaped slots of quarter wavelength are introduced in radiating element. The extraction procedure of negative permittivity for the proposed CSRR is discussed in detail. The proposed antenna is fabricated and measured. Simulated and measured results are in good agreement. Omni directional radiation pattern is obtained in H-plane and bi directional radiation pattern is obtained in E-plane. Parametric study of CSRR and C-shaped slot are examined to obtain best results. The proposed antenna has significant advantages, including low profile, miniaturization ability, and good impedance matching.     

Transverse slot antenna array in the broad wall of a rectangular waveguide partially filled with a dielectric slab

A compact and wide-band transverse slot antenna array in the broad wall of a rectangular waveguide partially filled with an H-plane -dielectric slab is presented in this paper. By partially filling an H-plane dielectric slab in the waveguide, the inter-element spacing between slots is reduced to be about 0.8 free-space wavelengths to avoid grating lobes. In addition, the partially filled material provides extra flexibility to adjust the slot impedance as desired within a relatively wide frequency range. A new feeding network is designed for this antenna array, which can prevent the shift in the pointing angle of the array's main radiation beam with the change of frequency. Experimental data for a 2/spl times/4 antenna array operating at X-band show that stable radiation pattern over a wide frequency range can be obtained. The measured gain is 16.9 dB at 10 GHz and the fluctuation is less than 2 dB over a frequency band of 1.5 GHz. The slot array's 10-dB return loss bandwidth is 13% and the cross-polarization level is better than -25 dB.     

Current transport and formation of energy structures in narrow Au/n-GaAs Schottky diodes

The current transport and formations of potential barrier height in narrow Au/n-GaAs Schottky diodes (SD) with a contact surface in length of 200 μm, width of 1 and 4 μm have been investigated.It was determined that features of current transport are in good agreements with the thermionic emission theory in the forward bias as like high-quality conventional (flat) SD. Features of current transport in the reverse bias also is well described by thermionic emission theory, but it has specific features unlike I–V characteristics flat SD.Forward bias of narrow SD current–voltage (I–U) characteristics are represented by straight lines in semi-logarithmic scale in a wide range, nearly nine order of current up to 0.7 V with near unit ideality factor. In the beginning of the reverse voltage, the current practically was extremely low, by increasing in voltage the current jump in steps approximately for 3–4 order in voltage of 3–4 V, then current increases linear for 3–5 order in semi-logarithmic scale by increasing in voltage up to nearly 7 V.Numerical values of parameters such as the saturation currents, the operating barrier height, ideality factor, dimensionless factor are obtained. The correlations between ideality factor and dimensionless factor were meaningful.The energy diagrams of narrow SD have been drawn in absence and presence of forward and reverse voltage. It is found that electronic processes in narrow SD are well described by energy model of real narrow metal–semiconductor contacts. The additional electric field arising in near contact area of the semiconductor because of creating contact potential difference between contact surface and to it adjoining free surfaces of the metal and semiconductor.     

Hexagonal boundary Sierpinski carpet fractal shaped compact ultrawideband antenna with band rejection functionality

In this paper a second iteration Sierpinski carpet fractal shape UWB antenna with hexagonal boundary is presented. The antenna covers the frequency band from 3 GHz to 12 GHz (VSWR ≤ 2). The proposed antenna has the capability to reject 5.15–5.825 GHz band assigned for IEEE802.11a and HIPERLAN/2 which is achieved by embedding a ‘Y’ shaped slot in the radiator that extends to the central conductor of the CPW feed as well. A fabricated prototype is developed where the simulation and experimental results are in good agreement. Measured peak antenna gain varies from 1.25 dBi to 6 dBi within the band. The proposed antenna has a compact size of 33 mm × 32 mm that includes the substrate around the radiating element. Time domain characteristic reveal that the antenna is non-dispersive with a variation of measured group delay within 0.5 ns over the entire band.     

非大气窗口毫米波长槽漏波波导天线的设计

设计了一种非大气窗口毫米波长槽漏波波导天线,分析槽的长度、宽度对天线性能的影响,并运用插值法缩减天线槽长,优化天线的性能,减轻天线的重量。优化后的天线具有高增益、低副瓣、窄波束、主波束前倾、E面方向图近似圆形等特点。在结构设计上,采用UG385波导接口连接射频部件,提高馈电与天线的匹配性;同时,对天线内表面进行镀金处理,提高天线表面的光洁度,减小损耗。仿真和测试结果表明,该天线能够满足非大气窗口毫米波雷达对天线的指标要求。     

A Compact Monopulse Radial Line Slot Array Antenna at Millimeter Wavelengths

This paper describes the design and performance of a radial line slot array antenna (RLSA) which generates sum or difference far field patterns. The antenna consists of rectangular waveguide to radial line transition, radial line and slot arrays etched on the upper plate of the radial line. A novel rectangular waveguide to radial line transition is designed to build up the dominate TEM mode in radial line to excite the slot arrays which are arranged in concentric rings on the upper plate of the radial line. The antenna radiates linear polarization at Ka band. Monopulse operation is obtained by a sum and difference network which is a compact eight-port comparator consisting of coplanar magic tees. The sum and difference network is waveguide structure whose loss is less than that of microstrip structure at millimeter wave lengths. The monopulse performances can be used in monopulse tracking and anti-collision application etc. Genetic algorithm (GA) is applied to optimize the parameters of the transition and antenna to obtain good performances.