Corrugated SIW K band horn antenna

In the recent years, the strong demand for high performance, low cost and high gain antennas for telecommunication, surveillance, and imaging applications has rapidly grown at microwave and higher frequencies. High speed wireless links require modular, compact size and high directivity with low cross polarization antennas. To demonstrate the proposed concepts and design features, in this paper, a substrate integrated waveguide (SIW) feeding technique has been created having well behaved gain and suitable −10 dB bandwidth from 23.8 GHz to 25.7 GHz (roughly 2 GHz bandwidth), while the impedance bandwidth for VSWR < 2.5 is nearly 3 GHz. The simulated antenna attains 12.5 ± 1 dB gain over majority of K band with an occupied size of 82 mm × 40 mm × 2.54 mm and has roughly 95% radiation efficiency. The proposed antenna is an excellent candidate for integrated low cost K band and even higher frequency systems. The simulations are done by two full wave packages i.e. ANSYS HFSS and CST MWS that associated with finite element method (FEM) and finite difference time domain (FDTD), respectively. The results show good agreements between these two methods.     

Offset spherical dual-reflector antenna

The dual offset spherical reflector antenna offers the advantage of a circularly symmetric main reflector together with a subreflector possessing an axis of symmetry. These features could lead to significant cost reductions in manufacture compared to existing offset designs. Initial results of a parametric study, using physical optics, show that 64% efficiency is possible with a peak crosspolar level below ?35 dB, together with very low sidelobes.     

Real-time spherical near-field handset antenna measurements

A new spherical near-field measurement system, dedicated to personal-communications applications, has been installed at e-tenna Corporation. The system, sold by Satimo, uses an electronically scanned probe array, and offers a dramatic reduction of the measurement time (by a factor ranging from 60 to 1,000) with respect to conventional mechanical scanners. This test range has undergone extensive acceptance testing, which has verified the specified measurement accuracy. The speed of the system, combined with the availability of full-sphere measurement data, enables rapid measurement of antenna efficiency. The system also enables the measurement of other parameters, such as the percentage of radiated power dissipated into the body of a human test subject operating a cellular telephone     

Early-time response of the spherical antenna

The early-time response of the spherical antenna is determined by a two-step process. First, the high-frequency representation is derived by the technique known as the Watson transformation. The high-frequency results are then Fourier transformed to obtain the time response. The time region where these results are valid is given and comparisons to previous analyses are made. Conclusions regarding the utility of this method to other antenna shapes and different time regions are discussed.     

Parameters of a spherical random antenna array

The shape of the beam of a spherical random antenna array is discussed and the main parameters, such as bandwidth, beamwidth and hyperfocal distance are determined.     

Phase mode processing for spherical antenna arrays

It is shown how the concept of phase mode excitation of circular antenna arrays may be extended to spherical arrays, and in particular that a spherical phase mode of the excitation function of a spherical array results in a far field radiation pattern with the same spherical phase mode form. A number of applications and issues concerned with the practical implementation are discussed.     

Radiation characteristics of spherical triangular array antenna

Radiation characteristics of a type of spherical triangular array composed of turnstile elements are numerically analyzed and discussed. It is found that the spherical array proposed here is able to scan its beam up to large angle without variation of the directivity and the circular polarization property.     

Insulated loop antenna in a conducting spherical shell

Wait has calculated the impedance seen by a small circular loop of wire placed in an insulating spherical cavity in an infinite homogeneous conducting dielectric. The same technique may be used to compute the impedance of a loop inside a spherical shell. Attention is focused on the change in impedance of an electrically small wire loop when it is placed inside a spherical shell of lossy dielectric material whose radius is small compared to the free-space wavelength. The self-impedance in the absence of the shell can be calculated separately. Simple formulas are developed for the case where the conduction currents in the shell dominate over displacement currents and the shell is thin compared to the skin depth.     

A canonical problem in transient radiation--Tthe spherical antenna

The canonical problem of a spherical metal antenna excited at an equatorial gap by an azimuthally independent step voltage is solved. The early-time and late-time behavior of the field is discussed for both nondispersive and dispersive homogeneous isotropic environments. Conclusions are drawn regarding the solution of transient radiation or scattering problems for metal bodies of arbitrary shape.     

Wideband feed system of a spherical mirror antenna

Analysis of input characteristics of a helical cylinder antenna and helixes crosstalk in array with few elements is performed. Construction of a wideband feed in the form of sphere-cylinder antenna is suggested.     

Generation of dual beams from spherical phased array antenna

An active X-band spherical phased array developed for transmitting high bit rate data from remote sensing satellites to two ground stations simultaneously is presented. Resolution of the dual phase adjustment of the phase shifters, which are common to generate two beams, is discussed.     

Calculated scan characteristics of a large spherical reflector antenna

A previously published numerical method to calculate the radiation properties of parabolic reflectors has been modified to also include very large spherical reflectors. The method has been verified by comparing the calculated and the measured results for a 120-wavelength spherical reflector.     

A scanning spherical tri-reflector antenna with a moving flatmirror

Spherical reflector systems can achieve pattern scanning without rotation of the main reflector through the use of multiple subreflectors that can move. Also, two subreflectors can be shaped to correct for spherical aberration and to control the aperture distribution on the spherical main reflector. In a previous paper (see ibid., vol.41, p.778, no.6, 1993) we introduced a method that offers both aperture phase and intensity control and scans the main beam without an accompanying movement of the illuminated area over main reflector. The method can overcome the poor aperture utilization problem common in spherical reflector antenna systems; however, it requires motion of the entire subreflector system, including the feed, during scan. In this paper we discuss a method that does not require motion of the subreflector system during scan. This method employs a flat mirror that creates a virtual image of the subreflector system. The motion of the subreflector system in the previous design is replaced by the motion of the virtual image that is controlled by the motion of the flat mirror. The new design offers simplified mechanical motion, while maintaining beam efficiency performance comparable to that of traditional spherical tri-reflector scanning antennas, but with some sacrifice in aperture efficiency and cross-polarization performance     

Controlling the radiation pattern of a spherical mirror antenna

Creation possibility of spherical mirror antenna’s irradiating system based on a few-element array of cylindrical spiral radiators to increase the radiation directivity and to control the radiation pattern’s form in a wide frequency band is shown.     

8毫米波均匀介质球透镜多波束天线的研究

介绍了均匀介质球透镜天线基本特点;仿真分析了单馈源时均匀介质球透镜天线的辐射性能;在单馈源的基础上,仿真分析了8馈源时的辐射性能。根据仿真结果加工了均匀介质球透镜,同时设计制作了包括16个圆波导的馈电网络以及馈电网络的数字控制器。在馈电网络中16个圆波导沿介质球周围成弧形排成上下2层,每层8个。通过同一层上的馈电单元之间的切换实现水平扫描,而通过切换不同层上的馈电单元实现垂直扫描。实测结果表明均匀介质球扫描天线性能良好。     

A circularly polarized conical beam spherical slot array antenna

This paper proposes a circularly polarized conical beam spherical slot array antenna which is suitable for a low elevation angle land mobile satellite communication subscriber. The structure of this antenna type is very simple to fabricate; i.e. a ring of perpendicular slot pairs is cut on an outer surface of a concentric conducting spherical cavity. From the assumption of weak coupling of the slots from the cavity, the conical beam pattern can be obtained. Experimental results that verify the conical beam radiation are in good agreement with the design.     

The input impedance and the antenna gain of the spherical helicalantenna

The input impedance and the antenna gain of the spherical helical antenna are obtained theoretically and experimentally. Results indicate the better performance of the 3-turn antenna over the 7-turn one in terms of the impedance bandwidth and the stability of the antenna gain. The theoretical current distribution is also obtained and its salient characteristics are discussed     

Radiation from a spherical aperature antenna immersed in a compressible plasma

The exterior boundary-value problem for a sphere immersed in a compressible plasma medium is solved. The model is a perfectly conducting sphere excited by an aperture, in its surface, which has a specified distribution of the tangential electric field. The configuration is such that Maxwell's equations, when combined with the continuum theory of fluid dynamics, are separable. The sheath at the interface with the plasma is characterized by an absorptive boundary condition which assumes a linear relationship between the pressure and the mean velocity of the electrons. It is shown that the TM (transverse magnetic) waves are coupled with the electroacoustic waves, while the TE (transverse electric) waves are decoupled. Some numerical results are presented which show, in quantitative manner, the relative fraction of the total power which is radiated in the form of electroacoustic waves.