共查询到20条相似文献,搜索用时 15 毫秒
1.
V. E. Lyubchenko V. D. Kotov E. O. Yunevich 《Radiophysics and Quantum Electronics》2003,46(8-9):717-721
Continuous electromagnetic emission from a Gunn diode built in a microstrip log-periodic antenna in the frequency range from 25 to 60 GHz is studied experimentally. The microstrip antenna was located on an insulating substrate with a thickness of about a quarter of the wavelength and with a metallized back side. It is shown that the output radiation power of such an antenna reaches 5 mW, which is over 50% of the power received from similar diodes in the waveguide cavity. The oscillation regime was varied from single-mode to noise-like, depending on the dielectric thickness and could be synchronized by external emission. Such a quasi-optical structure based on a Gunn diode is convenient for summing up powers from individual oscillators in an open resonator and is of great interest for the terahertz frequency band. 相似文献
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We analyze the possibility for obtaining relevant boundary conditions of the diffraction problem of radiation of an extended piezoceramic antenna in a borehole. The method of equivalent electromechanical circuits is used to search for relationships between the characteristics of the antenna and the radiated fields of elastic vibrations. It is shown that the optimal conditions for transfer of acoustic energy from a borehole to a massif in the considered case drastically differ from similar conditions corresponding to ideal boundary conditions. The expressions for the potentials of displacements in the massif are obtained. Experimental data confirming the analytical results are adduced. 相似文献
3.
N.P. Somasiri W.K. Toh X. Chen I.D. Robertson A.A. Rezazadeh 《International Journal of Infrared and Millimeter Waves》2002,23(12):1777-1785
This paper describes numerical modelling of a dual band multi-layered microstrip patch antenna operating at 35GHz on an in-house semi-insulating GaAs substrate. The simulated and measured resonant frequencies at both lower and upper resonant frequencies will be compared to check the accuracy of the different numerical modelling techniques. 相似文献
4.
Shaoyong Wang Qi Zhu Xiaohua Yun Shanjia Xu 《International Journal of Infrared and Millimeter Waves》2007,28(6):465-471
This paper describes the design of a novel cylindrical millimeter-wave microstrip antenna (MA) with broad beamwidth by means
of isotropic transformation (IT). A planar millimeter-wave antenna with broad beamwidth is designed first, and then IT is
used to design a conformal one based on the planar structure. In addition, phased array with eight present elements has been
designed as an example. Finally, numerical results are given to show that the present antenna possesses broad beamwidth and
its array is of large scanning angle, which also verify the validity of the method of IT. 相似文献
5.
Shaoyong Wang Qi Zhu Shanjia Xu 《International Journal of Infrared and Millimeter Waves》2007,28(7):513-519
Design of a novel compact millimeter-wave microstrip antenna with wide bandwidth and broad beamwidth is presented. In the
structure, multiple layers and a parasitic element as well as a coupling aperture are used to achieve wideband, while a conducting
cylinder and the coupling aperture are used to obtain broad beamwidth. Finally, phased array with eight present elements has
been designed as an example. Compared to traditional microstrip antennas and arrays, present antenna and array are of smaller
dimension and broader beamwidth as well as wider bandwidth. 相似文献
6.
The current distribution of a center-fed dipole cylindrical antenna of arbitrary dimension immersed in unbounded lossless warm plasma is considered, taking into account the commonly neglected end-cap effect. The approximated solution of the integral equation for the current distribution is obtained with the aid of Fourier analysis, and the expression is derived for the current distribution I(z) as the function of position z along the cylindrical surface of the antenna. Sample calculations are made for a half-wavelength dipole antenna with different values of thickness parameter ?=(a/l)<0.25 and of the normalized plasma density parameter po=(?p/?)2 <1. Here a and l denote the radius and the half-length of the antenna, respectively. ?p and ? denote the plasma angular frequency and the radiation angular frequency. The variation of the amplitude and phase of the current with the position, and the variation of radiation resistance with po and ? are examined and discussed in detail. 相似文献
7.
Giuliano F. Bastista Oliveira José Elesbão C. Neto Humberto C. Chaves Fernandes 《International Journal of Infrared and Millimeter Waves》2003,24(7):1159-1169
For the microstrip patch resonator, as a planar antenna of a microstrip, a set of equations that represents the electromagnetic fields in the x and z direction as function of the electric field in the y direction are obtained applying the TTL method. This method is very suitable at microwave and antenna applications, and gives accurate complex resonant frequency, which contributes definitively to obtain higher precision antenna parameters. For each type of array is calculated the array factor, considering the excitation, phase and the relative displacement between the elements as well as the dimensions and number of elements. 相似文献
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V. Sathi Ch. Ghobadi J. Nourinia 《International Journal of Infrared and Millimeter Waves》2008,29(10):897-905
Circular ring microstrip antennas have several interesting properties that make it attractive in wireless applications. Although
several analysis techniques such as cavity model, generalized transmission line model, Fourier-Hankel transform domain and
the method of matched asymptotic expansion have been studied by researchers, there is no efficient design tool that has been
incorporated with a suitable optimization algorithm. In this paper, the cavity model analysis along with the genetic optimization
algorithm is presented for the design of circular ring microstrip antennas. The method studied here is based on the well-known
cavity model and the optimization of the dimensions and feed point location of the circular ring antenna is performed via
the genetic optimization algorithm, to achieve an acceptable antenna operation around a desired resonance frequency. The antennas
designed by this efficient design procedure were realized experimentally, and the results are compared. In addition, these
results are also compared to the results obtained by the commercial electromagnetic simulation tool, the FEM based software,
HFSS by ANSOFT. 相似文献
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Vinod Kumar Singh Ashok Mittal 《International Journal of Infrared and Millimeter Waves》2000,21(2):277-283
This paper describes the Design of Broadside 8-Elements Microstrip Antenna Array at Ka-Band using corporate feed. Array is designed for the Broadband applications for 32 GHz to 36 GHz (4 GHz Bandwidth). The Gain of the Antenna Array is 18 dBi and the 3-dB Beamwidth in E - & H - Plane is 18 degree and 27 degree respectively with minimum sidelobe level of 15 dBc. Antenna test results show a close agreement between the designed and measured values. The Antenna Array has been printed on 10 mil RT-Duriod (r = 2.22) substrate. 相似文献
14.
Jin-Ping Xu Li-Ping Yang 《International Journal of Infrared and Millimeter Waves》1999,20(7):1339-1352
In this paper, a full-wave analysis using finite element method is presented to investigate the dispersion characteristics of inside cylindrical microstrip lines, which are essential to the design of some conformal microstrip circuits in millimeter wave bands. Numerical results of frequency-dependent effective dielectric constants are given for different structural dimensions and dielectric constants of substrate. Some useful conclusions are derived for the design of the special conformal microstrip lines. 相似文献
15.
Novel Broadband Reflectarray Antenna with Windmill-Shaped Elements for Millimeter-Wave Application 总被引:1,自引:0,他引:1
Hua Li Bing-Zhong Wang Ping Du 《International Journal of Infrared and Millimeter Waves》2007,28(5):339-344
A novel broadband millimeter-wave reflectarray antenna composed of windmill-shaped elements of variable lengths is proposed.
Compared to the conventional single-layer reflectarray elements, the windmill-shaped elements can realize much larger phase
variation range (over 600°), leading to broader bandwidth. Using this technique, a 15°-beam-steering reflectarray operating
at 30 GHz is designed. The computed results demonstrate the agreement of the main beam steering with the design requirement,
and a 1-dB gain bandwidth close to 20% is obtained. The validity of the obtained results is verified by comparing the ones
generated by Ansoft High Frequency Structure Simulator (HFSS) with those produced by Ansoft Designer. The antenna is useful
for millimeter-wave applications.
This work was supported by the National Natural Science Foundation of China (No. 90505001), the High-Tech Research and Development
Program of China (No. 2006AA01Z275), and the Creative Research Group Program of UESTC. 相似文献
16.
Zaboronkova T. M. Zaitseva A. S. Kudrin A. V. Yurasova N. V. 《Technical Physics》2019,64(10):1515-1522
Technical Physics - Electrodynamic characteristics of an antenna in the form of an infinitesimally thin, perfectly conducting narrow strip located at a plane interface of a uniaxial magnetic... 相似文献
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《理论物理通讯》2017,(3)
We study a problem of two-point resistance in a non-regular m × n cylindrical network with a zero resistor axis and two arbitrary boundaries by means of the Recursion-Transform method. This is a new problem never solved before, the Green's function technique and the Laplacian matrix approach are invalid in this case. A disordered network with arbitrary boundaries is a basic model in many physical systems or real world systems, however looking for the exact calculation of the resistance of a binary resistor network is important but difficult in the case of the arbitrary boundaries, the boundary is like a wall or trap which affects the behavior of finite network. In this paper we obtain a general resistance formula of a non-regular m × n cylindrical network, which is composed of a single summation. Further,the current distribution is given explicitly as a byproduct of the method. As applications, several interesting results are derived by making special cases from the general formula. 相似文献
19.
设计了一种用于无源射频识标签,中心谐振频率为2.45GHz的圆极化微带贴片天线。设计中引入了Rogers RO4232 (tm),Rogers RO4003 (tm)以及玻璃短纤维增强聚四氟乙稀三种材质的复合基底,利用Ansoft HFSS 10.0进行建模,并对设计模块进行仿真和优化处理,仿真结果表明天线的方向性良好,有效增益为5.534dB, 带宽>50MHz(S11<-15dB),阻抗匹配良好。驻波比、辐射效率均与理论期望吻合,各项指标达到了航空配件管理及维修记录的实际需求且易于实现,价格低廉,可靠性好。 相似文献
20.
This paper discusses the problem of gravitational perturbations of radiating spacetimes. We lay out the theoretical framework for describing the interaction of external gravitational fields with a radiating spacetime. This is done by deriving the field perturbation equations for a radiating metric. The equations are then specialized to a Vaidya spacetime. For the Hiscock ansatz of a linear mass model of a radiating blackhole the equations are found separable. Further, the resulting ordinary differential equations are found to admit analytic solutions. We obtain the solutions and discuss their characteristics. 相似文献