Ku band pattern reconfigurable substrate integrated waveguide leaky wave horn antenna

A dual band substrate integrated waveguide H plane sectoral horn antenna with reconfigurable radiation characteristics has been proposed in this paper. Designed antenna acts as a perfect broadside radiator at 16.1 GHz and perfect endfire radiator at 14.4 GHz frequency. Broadside radiation has been achieved by etching rectangular slots in the flared section of horn exhibiting a gain of 8.87 dBi. To achieve perfect endfire radiation, dielectric loading is done at the edge of horn and at this frequency antenna shows a gain of 11.3 dBi. The horn and the loaded dielectric are integrated by using the same single substrate resulting in easy fabrication and low cost. The proposed design has been fabricated and measured results are in good agreement with the simulated results.     

Dielectric properties of single crystals of Al2O3, LaAlO3, NdGaO3, SrTiO3, and MgOat cryogenic temperatures

A dielectric resonator technique has been used for measurements of the permittivity and dielectric loss tangent of single-crystal dielectric substrates in the temperature range 20-300 K at microwave frequencies. Application of superconducting films made it possible to determine dielectric loss tangents of about 5×10^-7 at 20 K. Two permittivity tensor components for uniaxially anisotropic samples were measured. Generally, single-crystal samples made of the same material by different manufacturers or by different processes save significantly different losses, although they have essentially the same permittivities. The permittivity of one crystalline ferroelectric substrate, SrTiO₃, strongly depends on temperature. This temperature dependence can affect the performance of ferroelectric thin-film microwave devices, such as electronically tunable phase shifters, mixers, delay lines and filters     

一种双频双极化宽带高温超导微带天线的研究

为了提高天线的性能,本文设计了一种口径耦合馈电的多层介质高温超导微带天线。天线的馈电网络部分采 用了高温超导材料,利用了高温超导材料具有低表面阻抗的特性,提高了天线的效率。高温超导微带天线的衬底介电 常数过高,多层介质的结构引入一层真空衬底,降低平均介电常数,这样能展宽天线的带宽。天线缝隙采用H 型缝 隙,提高了两极化端口间的隔离度。天线的仿真结果表明了设计思路的合理性和可行性。     

Submillimeter-wave antennas on thin membranes

Submillimeter-wave antennas have been fabricated on 1-μm thick silicon-oxynitride membranes. This approach results in better patterns than previous lens-coupled antennas, and eliminates the dielectric loss associated with the substrate lens. Measurements on a wideband log-periodic antenna at 700 GHz, 370 GHz and 167 GHz show no sidelobes and 3-dB beamwidths between 40° and 60°. A linear imaging array has similar patterns at 700 GHz. Possible applications for membrane antennas include wideband superconducting tunnel-junction receivers for radio astronomy and imaging arrays for radiometry and plasma diagnostics.     

A compact CPW fed slot antenna for ultra wide band applications

A printed compact coplanar waveguide fed triangular slot antenna for ultra wide band (UWB) communication systems is presented. The antenna comprises of a triangular slot loaded ground plane with a T shaped strip radiator to enhance the bandwidth and radiation. This compact antenna has a dimension of 26 mm × 26 mm when printed on a substrate of dielectric constant 4.4 and thickness 1.6 mm. Design equations are implemented and validated for different substrates. The pulse distortion is insignificant and is verified by the measured antenna performance with high signal fidelity and virtually steady group delay. The simulation and experiment reveal that the proposed antenna exhibits good impedance match, stable radiation patterns and constant gain and group delay over the entire operating band.     

基于Polys try介质基板微带天线的应用研究

针对传统贴片天线检测频率有限(2~35 GHz)且由于增益低导致检测结果不明显的问题,文中提出了以聚苯乙烯作为介质基板构建微带天线的解决方案。在以介电材料玻璃超细纤维为介质基板的理论基础上,采用高分子材料Polysty作为介质基板构建微带天线模型。结合经典天线理论计算辐射贴片以及介质基板尺寸;基于HFSS搭建Polysty作为介质基板的模型并根据微带天线特性将理论设计的微带天线参数进行优化,最终得到在1 GHz时微带天线的最佳尺寸。仿真及实验结果表明,Polysty作为介质基板的微带天线中心频率可以达到1 GHz,增益高并且检测角度范围大。     

The Millimeter Wave Radiation of a Dielectric Leaky-Wave Antenna Coupled with a Diffraction Grating for the Broadside Radiation: Narrow-Face Interaction

A dielectric leaky-wave antenna (DLWA) coupled with a metallic diffraction grating is experimentally investigated in millimeter-waves. The interaction between dielectric line and grating is from the narrow-face of dielectric and it is contactless. Measured patterns are compared with simulated ones. The antenna parameters (HPBW, side lobe levels, etc.) are also obtained. The most significant achievement of this antenna is to obtain broadside radiation without any suppression, which occurs due to the periodicity of grating. This situation is not available for the most of the periodic leaky-wave antennas. This antenna type can be used as a broadside radiator by this property as well as a frequency scanning purposes.     

Excitation of a cylindrical microstrip structure with arbitrarily shaped printed elements by a plane wave

The problem of excitation of a cylindrical microstrip structure by a plane wave is considered. The structure is a printed element on a circular dielectric substrate containing a coaxial metal cylinder. In the scattering regime, the structure under study adequately simulates a cylindrical microstrip antenna operating at resonance frequencies. The printed element is equivalent to the radiator of this antenna. The problem is solved in the spectral domain with the use of the method of moments and piecewise-specified basis functions. The effect of the radiator’s shape on the radar cross section of the structure is investigated. It is shown that a change in the radiator’s topology substantially affects the formation of new oscillation modes whose resonance frequencies noticeably shift to the lower frequency region from their positions in the case of a radiator having a rectangular cylindrical shape.     

一种高介GPS微带天线的设计与研究

针对传统GPS天线体积较大的问题,提出了一种改进的圆极化微带贴片天线,该天线用高介电常数的陶瓷作为天线基板,采用单端口背馈方式馈电,缩小了天线尺寸,结构简单。通过仿真优化,获得了比较好的阻抗带宽和轴比带宽,并以此为基础研究了介质基板厚度及损耗对天线性能的影响,为GPS微带天线设计提供一种思路。     

A low-loss unidirectional dielectric radiator (UDR) for antenna andspace power combining circuits

A low-loss unidirectional dielectric radiator (UDR) is proposed for applications to antenna and space power combining circuits. The operating principle of this novel radiator is explained in detail. Experimental prototypes using polystyrene are fabricated and measured around 9.5 GHz. A coaxial open-ended probe is used to excite this resonant radiator. A detailed study based on experimental results demonstrates interesting characteristics of a broad-beam with gain of up to 10 dBi and low cross-polarization. This type of radiator may find millimeter-wave applications in mobile and satellite communication systems     

Design of Printed Resonant Antennas for Monolithic-Diode Detectors

Model experiments at 10-GHz band have been performed to obtain optimum structures of printed resonant antennas for monolithic GaAs Schottky-diode detectors in the submillimeter-wave region. Design charts for antenna structures, which are also useful for a thin-film metal-to-metal diode structure on a dielectric substrate, are presented.     

一种二叉树状分形偶极子天线的设计

提出了一种基于二叉树状分形结构的分形偶极子贴片天线。该天线的介质基片采用相对介电常数为4.4,介电损耗角正切为0.02的FR4介质板,由微带线经阻抗变换后进行馈电。该天线利用分形技术实现了33%的尺寸缩减;通过平行双线结构和开U型槽技术,优化了阻抗匹配,降低了天线的谐振频率。通过仿真分析与模型优化,天线的最终尺寸为35 mm×22 mm×1.6 mm,中心工作频率为2.87 GHz,工作频率为2.77~2.97 GHz,-10 dB阻抗相对带宽为6.9%,工作频带内最小回波损耗可达-49 dB,最大增益可达2.36 dB。该天线具有小型化、阻抗匹配良好的优点,在当代小型化通信系统中具有良好的应用前景。     

Aperture-coupled thin-film superconducting meander antennas

A thin-film superconducting meander patch antenna coupled by an H-shaped aperture is proposed. It is analyzed using a full wave electromagnetic simulator and the theory of cavity model for microstrip patch antennas. The meander patch was fabricated from a single-sided film of YBCO (YBa₂CU₃O₇) on MgO with a typical transition temperature of 90 K. Simulated results are presented for return loss, radiation pattern, and efficiency and these are shown in good agreement with the results obtained from network analyzer measurements. An array of a number of elements is also proposed for wide-band operation     

Ultralow Temperature Processing and Integration of Dielectric Resonators on Silicon Substrates for System-on-Chip Applications

Ultralow temperature processing of Ba₂Ti₉O₂₀ thin-film ceramics and the attachment of a porous dielectric resonator cylinder on a conducting prepatterned silicon substrate have been accomplished using a hydrothermal process at 150degC/3 h. Enhanced densification and mechanical strength at the bulk ceramic-thin-film interface were induced by a dissolution-crystallization process involving a sol-gel solution under 13-15 atm pressure. Recrystallization forms electrical bridges between powder particles to form an interconnected microstructure, which eliminates grain boundary defects and, hence, improves the dielectric properties. This method has potential for growth of dielectric resonators on integrated circuits for system-on-chip applications and is implemented for the fabrication of an integrated dielectric resonator antenna.     

A new inverted F antenna with a ring dielectric resonator

A new antenna combining the use of a ring dielectric resonator (DR) and an inverted F antenna (IFA) is proposed and investigated experimentally. In this application, the DR not only fills the role of a dielectric coating, but also serves the function of a radiator. The measurements of input impedance, return loss, and radiation pattern for both the IFA with the DR (IFA-DR) and the wire IFA (WIFA) are conducted at the S band. The measured data demonstrate that the IFA-DR operates in multiple resonance modes unlike a WIFA. Compared with the WIFA, the one proposed here incorporating a ring DR and an IFA is more attractive in having a smaller size and a larger impedance bandwidth     

Patch antennas on externally perforated high dielectric constantsubstrates

Smaller physical size and wider bandwidth are two antenna engineering goals of great interest in the wireless world. To this end, the concept of external substrate perforation is applied to patch antennas in this paper. The goal was to overcome the undesirable features of thick and high dielectric constant substrates for patch antennas without sacrificing any of the desired features, namely, small element size and bandwidth. The idea is to use substrate perforation exterior to the patch to lower the effective dielectric constant of the substrate surrounding the patch. This change in the effective dielectric constant has been observed to help mitigate the unwanted interference pattern of edge diffraction/scattering and leaky waves. The numerical data presented in this paper were generated using the finite-difference time-domain (FDTD) technique. Using this numerical method, a patch antenna was simulated on finite-sized ground planes of two different substrate thicknesses, with and without external substrate perforation. The computations showed the directivity drop in the radiation pattern caused by substrate propagation was noticeably improved by introducing the substrate perforation external to the patch for the case of a patch antenna on a relatively thick substrate without any loss of bandwidth. Measurements of a few patch antennas fabricated on high dielectric constant substrates with and without substrate perforation are included for completeness. Good correlation between the computed results and measurements is observed     

Ultra wideband monopole/dielectric resonator antenna

A hybrid antenna is presented, consisting of an annular dielectric resonator antenna combined with a quarter-wave monopole to simultaneously act as a radiator and a loading element, producing an ultra wideband response. A prototype antenna is designed and a 3:1 bandwidth is demonstrated.     

Small Printed Ultrawideband Antenna With Reduced Ground Plane Effect

A small printed antenna is described with a reduced ground-plane effect for ultrawideband (UWB) applications. The radiator and ground plane of the antenna are etched onto a piece of printed circuit board (PCB) with an overall size of 25mmtimes25 mmtimes1.5 mm. A notch is cut from the radiator while a strip is asymmetrically attached to the radiator. The simulation and measurement show that the miniaturized antenna achieves a broad operating bandwidth of 2.9-11.6 GHz for a 10-dB return loss. In particular, the ground-plane effect on impedance performance is greatly reduced by cutting the notch from the radiator because the electric currents on the ground plane are significantly suppressed at the lower edge operating frequencies. The antenna features three-dimensional omni-directional radiation with high radiation efficiency of 79%-95% across the UWB bandwidth. In addition, a parametric study of the geometric and electric parameters of the proposed antenna will be able to provide antenna engineers with more design information     

Slot-coupled dielectric resonator antenna using a proximity feed ona perpendicular substrate

The slot-coupled dielectric resonator antenna with a proximity feed on a perpendicular substrate is investigated experimentally. The return loss, radiation pattern, and antenna gain of the new configuration are measured and discussed     

An E-plane ferrite loaded simple waveguide radiator

Experimental investigations were conducted to examine the effect of dielectric loading on a ferrite loaded waveguide radiator (notch antenna). The antenna was made by symmetrically tapering an X-band waveguide. A cylindrical ferrite post was disposed at the apex of the notch and it was biased with a dc magnetic field. The antenna was tested for several notch angles namely 140/spl deg/, 120/spl deg/, 90/spl deg/, 80/spl deg/, 60/spl deg/ while ferrite was loaded with several dielectric sleeves, such as wood, polymer, pyrex. The dielectric loading with high permittivity material is found to give better radiation and scanning characteristics. The radial thickness of the dielectric ring is observed to affect the radiation.