Simplified Calculation of Antenna Patterns, with Application to Radome Problems

Generally, the calculation of antenna far-field patterns from known near-field distributions is tedious and may require the use of a large computer. The calculations are simplified for certain types of antennas having separable near fields. This simplifying assumption is found to yield satisfactory results with pyramidal horns and parabolic reflector antennas. Calculations are further simplified by approximating a complex line integral with two real summations. Measured and calculated far-field patterns are included to indicate the accuracy of the calculations. Results are presented for horns and parabolic antennas and for a horn covered with a hollow dielectric wedge. The method is applicable to both E-plane and H-plane pattern calculations. The main lobe of a far-field pattern is calculated in less than one hour on a desk calculating machine by the simplified method. In radome work an important feature is that it permits rapid evaluation of the far-field distortion associated with any given near-field distortion in any given small region in the near field.     

Dual polarisation of microstrip reflectarray antenna

Dual polarisation of a microstrip reflectarray was demonstrated for the first time. A 16 element array of square microstrip patch antennas operating in the X-band was used to reflect the main beam 20" off broadside in both the E-plane and H-plane     

一种能产生针状波束和扇形波束的面天线

本文设计出了一种既能产生针状波束又能产生扇形波束的新型面天线,该天线的增益和方向图通过理论计算计算出来。本文设计实例中的面天线的针状波束的E、H平面的半功率宽度分别为2.320、2.240,而扇形波束的E、H平面的半功率宽度分别为2.010,6.40。     

Curvature effects on the mutual coupling of cylindrical-rectangularmicrostrip antennas

The mutual coupling between two cylindrical-rectangular microstrip antennas is studied from the application of the generalised transmission line model (GTLM). Theoretical solutions and measured results of both E-plane and H-plane coupling coefficients are presented. The curvature effects on the mutual coupling are discussed     

二单元圆极化微带天线阵列中 介质边缘效应仿真实验分析*

紧凑型双馈圆极化微带天线阵列在E面和H面存在严重互耦,会导致天线阵列的整体性能显著下降.为此,设计了二单元圆极化微带天线阵列,建立了参数化HFSS模型,对天线单元间距、辐射基片切向方向边缘效应对E面和H面互耦影响进行了仿真和分析,结果表明存在临界单元间距值.小于该值时,H面的互耦比E面的严重,反之H面的互耦会随着间距加大而显著下降;对于E面互耦,辐射基片切向方向的介质边缘存在对应最小E面互耦的最佳尺寸,但对于H面互耦,介质边缘效应并不显著.进一步设计了具有典型参数值的实物样品,测试结果验证了上述情况,并表明:介质边缘效应只能改善E面互耦,但对H面互耦的改善需要采用其它方法.     

基于介质波导混合模式的双频馈源喇叭天线

随着大型反射面天线技术的不断发展,天线系统对设备功能的多样化与一体化提出了更高的要求,馈源作为大型反射面天线的核心,其性能决定了反射面天线整体特性.文章基于介质波导混合模式提出了一种介质加载双频馈源喇叭天线,工作于X(7.25～7.75 GHz)/Ka(21～22 GHz)频段.利用特征值理论求解双层介质波导中电磁场表...     

基于双负材料的宽频带微带天线设计

采用空腔模型法设计了以双负材料(ε、μ为负值)为介质衬底的新型微带天线。实物测试表明:新型天线比普通材料微带天线明显展宽带宽。在未对天线贴片作优化处理的情况下,新型天线–10 dB反射系数带宽达1.50 GHz,比普通材料的天线展宽约70%,相对带宽达16.3%,E面辐射方向图较前者偏转了约40°,而H面方向图则与普通材料天线相似。     

Design of Compact Planar Triple Band-Notch Monopole Antenna for Ultra-wideband Applications

In this article a microstrip-fed mickey shaped monopole antenna with triple notched band characteristics for ultra-wideband applications is presented. By etching two slots in the ground plane, improved VSWR bandwidth is achieved. Mickey shape radiating patch provides 10 dB return-loss bandwidth from 3.10 to 10.60 GHz. By etching three simple C-shaped slots on the radiating patch, three existing wireless communication systems which interfere with UWB band is removed which includes WiMAX IEEE802.16 (3.30–3.80 GHz), WLAN IEEE802.11a/h/j/n (5.15–5.35, 5.25–5.35, 5.47–5.725, 5.725–5.825 GHz) and X-band downlink satellite system (7.1–7.9 GHz). Experimental results reveal that the proposed antenna exhibits desirable radiation patterns in the far field, resulting omnidirectional like pattern in the H-plane and nearly dipole like pattern in the E-plane.     

Spatial power combining for two-dimensional structures

The two-dimensional (2-D) hybrid dielectric slab-beam open and closed waveguide systems are suitable for the design of planar quasi-optical integrated circuits and devices. An open system consisting of an active E-plane amplifier array consisting of Vivaldi-type antennas with MESFET and monolithic microwave integrated circuit (MMIC) devices was investigated. The 4×1 MESFET amplifier array generated 11 and 4.5 dB of amplifier and system gain, respectively, at 7.12 GHz, and the cascade MMTC Vivaldi-type antenna produced 24 dB of amplifier gain at 8.4 GHz. Also, experiments on a new 2-D H-plane parallel-plate closed system with a stripline slot antenna is introduced, and the wavebeam-mode theory is presented. The new system minimizes scattering and isolation losses associated with open structures. The amplifier gain of the closed system based on slot antennas is compared to the open system based on Vivaldi antennas     

矩形波导不连续性的有限元分析

本文应用Gelerkin有限元法对矩形波导H面和E面不连续性问题进行了研究,编制了一个通用的计算机程序.对矩形波导H面弯曲、E面弯曲以及T型结头进行了计算机辅助设计,理论计算与测试结果吻合很好,证明了本文方法的正确性.     

A Unified Approach to the Analysis of a Category of H-Plane Discontinuities

Based on the mode matching method, the generalized scattering parameters including the fundamental and higher order modes (multi-modes) are obtained for the discontinuity interface of a category of waveguide H-plane discontinuities. Then by using a general port-connection order-decrease method raised by the author, the whole discontinuity including the two interfaces and the intermediate part of finite length or zero length (as is the case for very thin inductive windows or irises) can be combined into one network, and the generalized scattering parameters of this network can be obtained from which the scattering parameters of the fundamental mode can be extracted. If needed, the equivalent circuit parameters can be calculated directly from the scattering parameters. Examples are given to show the validity and versatility of this new method for dielectric filled waveguide, inductive iris and/or window, E-plane metal and/or finline insert, and even the offset E-plane finline insert, etc.. Multiple inserts, windows and irises can also be analysed.     

Broadband CPS-fed Yagi-Uda antenna

A broadband coplanar stripline-fed Yagi-Uda antenna is presented. The antenna has a feedline structure that is much simpler than other Yagi- Uda antennas, and provides more design flexibility in arranging the reflector owing to the absence of a large ground plane. To improve the impedance match, a taper is inserted between the wide-line/ small-gap and the narrow-line/large-gap CPS. The proposed antenna has a bandwidth of 3.9?5.9 GHz for a 210 dB reflection coefficient and a gain of 6.5?8.0 dBi. At the centre frequency of 4.9 GHz, the antenna has gain of 7.1 dBi, and a half-power beamwidth (HPBW) of 73° in the E-plane and 98° in the H-plane.     

Two-dimensional scanning leaky-wave antenna by utilizing the phased array

An aperture-fed patch antenna array is connected to the open end of a short leaky-wave antenna (LWA) to demonstrate the two-dimensional beam-scanning capability in this paper. This design not only offers another radiation path of the reflected wave, but also creates another scanning radiation pattern on the back plane of the substrate. The reflected wave of the LWA is equally separated by a power divider, modulated by each varactor-tuned phase shifter, and injected into two radiating aperture-coupled antennas. The operated frequencies are tuned to control the LWA main position in the elevation plane; meanwhile, by tuning the phase difference between two phase shifters, the main beam of the aperture-coupled antenna array can be scanned in the backside E plane. Experimental result shows that the suppression of the reflected wave can be 7 dB at 10.0 GHz with a short LWA length of 6 cm (two wavelengths). The H-plane and backside E-plane scanning radiation patterns have great potential in many applications and provide more flexibility to traditional designs.     

Numerical evaluation of phase centres of corner reflector antennas

Phase centres in the principal H-plane of corner reflector antennas have been determined from computed and measured phase patterns using numerical methods. They are in reasonably good agreement with each other. The relation between the computed phase centre and various antenna parameters is investigated and presented as graphs.     

矩形反射柱体近旁天线辐射特性的计算应用几何绕射理论

本文用几何绕射理论分析计算了矩形反射柱体近旁偶极子和双环天线的水平辐射特性。研究了到达场点的直达波、反射波和柱体稜边各次绕射波之间的量值关系。分析了柱体边长、天线与柱体之间的相对位置和天线的馈电方式对合成场强方向图的影响。计算结果表明,需要对天线系统的有关参数进行优化设计,以得到最佳的全向辐射特性,本文的分析方法和结果为这类天线系统的优化设计提供了手段和依据。     

Wide bandwidth and broad beamwidth microstrip patch antenna

A novel wideband and broad-beam microstrip antenna loaded with gaps and stubs is proposed. The antenna is based on a two-layer stacked electromagnetic coupling microstrip patch antenna (ECMSA). The upper patch of the antenna is loaded with two arc gaps and three stubs. The ECMSA is used to achieve wide impedance bandwidth, while the gaps and stubs-loaded patch is used to obtain broad-beam. The impedance bandwidth is up to 34.6%. In this impedance bandwidth, the pattern bandwidth is 13%. In this pattern bandwidth, the 3 dB beamwidth of E-plane and H-plane remain stable and are about ±60°. Simulation results agree well with measured results.     

Wideband Dual-Polarized Patch Antenna With Broadband Baluns

A pair of novel 180deg broadband microstrip baluns are used to feed a dual-polarized patch antenna. The 180deg broadband balun delivers equal amplitude power division and consistent 180deg (plusmn5deg) phase shifting over a wide bandwidth (>50%). We demonstrate that for a dual-polarized quadruple L-probe square patch antenna, the use of the proposed 180deg broadband balun pair, in place of a conventional 180deg narrowband balun pair, provides improved input port isolation and reduced H-plane cross-polarization levels over a wider frequency range, while maintaining low E-plane cross-polarization levels and stable E- and H-plane co-polarization patterns throughout the impedance passband     

Aperture coupled beam steering microstrip antenna array fed bydielectric image line

Five- and eight-element patch antenna arrays linearly fed by dielectric image lines have been developed with good E-plane and H-plane patterns. The measured results and the calculated beam steering angles agree very well. Crosspolarisations are 20 dB and side lobes are 15 dB below the main lobe     

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.     

波导频率双工器的多模分析计算

该文用多模微波网络的方法来分析波导频率双工器。先将波导频率双工器在结构上分割(分解)为相对简单的单元部件(单元网络)群,进而逐个分析每一个单元部件的电磁场边值问题以获得该单元网络的多模网络散射参数,最后通过多模网络参数矩阵的级联,得到整个器件,即由所有单元网络构成的合成网络的整体散射参数。