一种微带馈电铲形终端椭圆缝隙超宽带天线

设计了一种具有铲形终端微带馈电椭圆缝隙及枝节调节和接地板阶梯凹槽的超宽带(UWB)天线。利用仿真软件HFSS分析了铲形半椭圆、椭圆缝隙及枝节、半圆切槽、接地板与辐射体间隙、接地板三角形切角和阶梯凹槽等结构对天线性能的影响,对天线结构参数进行了优化。实测天线的阻抗带宽为2.8~12.0 GHz,在3.1~10.6GHz范围内基本呈全向性,并且具有较稳定的增益,约为2.5~4.6 d Bi。该天线可广泛用于无线通信领域。     

CPW-fed dual-annular-ring slot antennas

A new type of CPW-fed dual-annular-slot antenna operated in the 5.8 GHz band is introduced. Both the inductive and the capacitive configurations are presented. The design considerations of the antennas are discussed. Measurement shows that the antennas have a wide bandwidth of 16% with a peak gain of 5.4 dBi for the inductive configuration and 7.8% with a peak gain of 4 dBi for the capacitive configuration.     

Integrated waveguide slot antennas

Waveguide slot antennas integrated on microwave laminate are presented, and single and dual slot antennas are described, which operate at 10 GHz.     

Studies of CPW-fed equilateral triangular-ring slot antennas and triangular-ring slot coupled patch antennas

Designs of coplanar waveguide (CPW)-fed equilateral triangular-ring slot antennas with tuning-stub and triangular-ring slot coupled patch antennas are proposed and experimentally investigated. The impedance matching of the resonant frequency can be obtained only by adjusting the tuning-stub length for the proposed triangular-ring slot antenna with tuning-stub. For the design of ring-slot coupled patch antenna, slightly changing the patch size causes the tunable frequency-ratio f/sub 2//f/sub 1/ between the first two operating frequencies to fall in the range of about 1.1-1.42. Details of the proposed designs are investigated by experimental as well as theoretical studies.     

Design of reconfigurable slot antennas

In this paper the design of a compact, efficient and electronically tunable antenna is presented. A single-fed resonant slot loaded with a series of PIN diode switches constitute the fundamental structure of the antenna. The antenna tuning is realized by changing its effective electrical length, which is controlled by the bias voltages of the solid state shunt switches along the slot antenna. Although the design is based on a resonant configuration, an effective bandwidth of 1.7:1 is obtained through this tuning without requiring a reconfigurable matching network. Four resonant frequencies from 540-890 MHz are selected in this bandwidth and very good matching is achieved for all resonant frequencies. Theoretical and experimental behavior of the antenna parameters is presented and it is demonstrated that the radiation pattern, efficiency and polarization state of the antenna remain essentially unaffected by the frequency tuning     

Astigmatism in tapered slot antennas

A series of scale model measurements of transverse electromagnetic mode tapered slot antennas are presented. They show that the beam launched by this type of antenna is astigmatic. It is shown how an off-axis spherical mirror can be used to correct this astigmatism to allow efficient coupling to quasi-optical systems. A millimetre wave antenna and mirror combination is described and, with the aid of solid state noise diodes, the coupling of the launched beam to a quasi-optical spectrometer is shown to be in good agreement with that predicted by the scale model measurements.     

Radiation from slot antennas on cones

Integral representations are given for the radiation field from slots on the surface of a semi-infinite conducting cone. The corresponding normal mode representations for delta function circumferential slots are evaluated numerically for various cone angles, slot positions, and azimuthal variations. Experimentally measured patterns for two finite models are reported and compared with the semi-infinite cone theory. In particular, effects due to finite cone length and finite tip radius are discussed.     

Novel slot antennas for harmonic suppression

In this paper, novel microstrip-fed slot antennas with simple structure are proposed to achieve suppression of harmonics. To obtain this operation, conductor lines connected with ground plane in rectangular and meander type slot antennas are used, which have wide-bandstop characteristic. From the measured input impedances and radiation patterns of the proposed antennas, the second and third harmonics are effectively suppressed.     

Size reduction of cavity-backed slot antennas

A technique for reducing the dimensions of the cavity of a cavity-backed slot antenna (CBSA) is presented, which facilitates proper fabrication and integration of miniaturized slot antennas on multilayer substrates. This is accomplished by replacing the solid metal around the traditional slot antennas with a specific metallic pattern that can be viewed as a series of parallel strip lines placed around the slot antenna. This metallic pattern is then modified by designing the parallel strips in a compact fashion to reduce the overall antenna dimensions and obtain a reduced-size CBSA. It is shown that, for a simple straight slot antenna, the overall occupied volume of the modified cavity backing the slot antenna can be reduced by more than 65% without affecting the high radiation efficiency of the antenna. A number of traditional cavity backed slot antennas and the proposed modified CBSAs are designed, fabricated, and measured. The reduced-size CBSAs show a very low input VSWR, low cross-polarized radiation levels, and high radiation efficiency. Despite their small ground plane size, the proposed cavity backed slot antennas have front-to-back ratio (FTBR) values in the range of 6-7 dB.     

Microstrip-fed slot array antenna having 45/spl deg/ inclined linear polarisation

A 45/spl deg/ inclined linearly polarised slot array antenna with microstrip line feed has been developed. To simplify the feed system, series feeding is adopted to excite the radiating slots. An eight-element slot array, with an operating frequency that is of 12 GHz band, has been designed and its characteristics are investigated by the moment method analysis. Measured results are also presented to validate the numerical evaluations.     

Endfire tapered slot antennas on dielectric substrates

Endfire tapered slot antennas are suitable for many integrated circuit applications, imaging and phased arrays. We report on an investigation of single elements of such antennas, including slots which are exponentially tapered (Vivaldi), linearly tapered (LTSA) and constant width (CWSA). For antennas of all types, a good general agreement is obtained for curves of beamwidth versus length, normalized to wavelength, when one compares the data with that for traveling-wave antennas published by Zucker. An important condition for this agreement is that the effective dielectric thickness, defined in the text, is in a certain optimum range. This condition is qualitatively explained in terms of the theory for traveling-wave antennas.     

Coplanar waveguide-fed slot antennas on cylindrical substrates

This paper describes cylindrical coplanar waveguide (CCPW)-fed slot and folded slot antennas encompassing cylindrical substrates. Using a 1.27 cm diameter Teflon substrate, antennas that operate around 7 GHz have been realized with gains of 1.5 dB (slot) and 2.8 dB (folded slot). The antennas have a well-defined pattern null of 8 dB along the side of the CCPW feedline. A 1.6 GHz slot antenna on a 1.27 cm diameter alumina substrate was also fabricated using a novel direct-write technique, and shown to have comparable performance characteristics.The results include measured data and simulated data using a 3D cylindrical finite difference time domain (FDTD) code.     

Dual circularly polarized radial line slot antennas

A radial line slot antenna (RLSA) is a circularly polarized high efficiency planar array. Two types of RLSAs, a single-layered and a double-layered one, have been released commercially for 12 GHz band DBS reception. The former adopts nonuniform slots excited by a radially outward traveling wave, while the latter has uniform ones excited by an inward traveling wave. The paper merges the two into a novel, dual circularly polarized RLSA. Minimum antenna gain of 33.5 dBi in a DBS bandwidth of 500 MHz is measured for a 0.55 m diameter antenna     

Design of single layer broadband slot antennas

A novel design for single layer slot antennas is presented. The antenna consists of a rectangular slot on the top of a substrate and two parasitic patches with a coplanar feed-line on the opposite side. The simulated and experimental data show good performances in terms of bandwidth and unidirectional radiation.     

CPW-fed slot antennas on multilayer dielectric substrates

Coplanar wave (CPW)-fed slot antennas printed on multilayer dielectric substrates are numerically analyzed using a full-wave integral equation technique and the method of moments. The Green's function is derived with an iterative formulation. Results obtained with a simplified and a rigorous model of the feeding CPW lines are compared. The mutual coupling between the slot antennas in an array environment is calculated for a three-layer high-low-high permittivity combination. The theoretical results are verified with measurements     

New techniques for exciting linearly tapered slot antennas with coplanar waveguide

Two new techniques for exciting a linearly tapered slot antenna (LTSA) with coplanar waveguide (CPW) are introduced. In the first approach, an air bridge is used to couple power from a CPW to an LTSA. In the second approach, power is electromagnetically coupled from a finite CPW (FCPW) to an LTSA. Measured results at 18 GHz show excellent return loss and radiation patterns.<>     

Microstrip antennas with suppressed radiation in horizontal directions and reduced coupling

Microstrip (patch) antennas usually strongly radiate in directions along the ground plane. This effect causes unwanted radiation patterns and increased coupling among array elements. Dielectric polarization currents are identified as physical sources of this radiation. A general technique is proposed to compensate these currents and suppress radiation in horizontal directions.     

A slot design for uniform aperture field distribution insingle-layered radial line slot antennas

A single-layered radial line slot antenna (RLSA) is proposed for a direct broadcast from a satellite (DBS) subscriber antenna. It utilizes a radially outward-traveling wave and the aperture field is intolerably tapered if the uniform slots are used. Two novel techniques are applied. First, the slot design for uniform aperture field distribution is introduced. Second, the radial line is terminated by a matching spiral, in place of a dummy load. It suppresses reflection and radiates all the residual power in circular polarization. For a model antenna of 600-mm diameter, the efficiency of 65% is observed     

A novel approach for miniaturization of slot antennas

With the virtual enforcement of the required boundary condition (BC) at the end of a slot antenna, the area occupied by the resonant antenna can be reduced. To achieve the required virtual BC, the two short circuits at the end of the resonant slot are replaced by some reactive BC, including inductive or capacitive loadings. The application of these loads is shown to reduce the size of the resonant slot antenna for a given resonant frequency without imposing any stringent condition on the impedance matching of the antenna. A procedure for designing this class of slot antennas for any arbitrary size is presented. The procedure is based on an equivalent circuit model for the antenna and its feed structure. The corresponding equivalent circuit parameters are extracted using a full-wave forward model in conjunction with a genetic algorithm optimizer. These parameters are employed to find a proper matching network so that a perfect match to a 50 /spl Omega/ line is obtained. For a prototype slot antenna with approximate dimensions of 0.05/spl lambda//sub 0//spl times/0.05/spl lambda//sub 0/ the impedance match is obtained, with a fairly high gain of -3dBi, for a very small ground plane (/spl ap/0.20/spl lambda//sub 0/). Since there are neither polarization nor mismatch losses, the antenna efficiency is limited only by the dielectric and ohmic losses.     

Measured mutual coupling between linearly tapered slot antennas

Mutual coupling between two linearly tapered slot antennas arranged in coplanar as well as stacked configurations has been measured. Results indicate that mutual coupling level generally decreases with antenna separations and varies with dielectric constant, and antenna lengths