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In this paper, a CP MIMO antenna system design capable of UHF band operation is presented. By using circular polarization and antenna diversity by selection of the antenna supported by RFID reader chip sets, This MIMO antenna system can have high receiving signal strength and larger antenna beam coverage area, making this design a suitable candidate for RFID application in warehouse tracking. Parameters...
The metallic revolving table, which is used to support the antenna during the measurement, greatly affects the radiation pattern of the antenna. In this paper, Log Periodic Dipole Array (LPDA) was simulated with and without the metallic revolving table using commercial software - FEKO. Simulated results in two situations were compared to analyze the effects due to the metallic revolving table. Finally,...
High gain microstrip antenna using a shorted square wall in the center of the square patch has been reported. In this letter, we presented a modified structure for such a high gain design. Shorting at the center of the patch can be realized by placing number of shorting posts along the radiating edges of the patch, and a CPW-feed structure was used to excite the patch antenna through a slot. It is...
This paper describes the radiation from an unbalanced-mode two-arm spiral antenna, where the antenna arms are defined by the Archimedean spiral function. The input impedance, current distribution, radiation pattern, axial ratio, and gain are investigated. The investigation reveals that the unbalanced-mode spiral radiates a circularly polarized wave over a wide frequency range as the balanced-mode...
A printed rectangular monopole antenna fed by a tapered coplanar waveguide (CWP) with a band-notched characteristic is proposed for ultra wideband (UWB) applications. It is shown that the notched or rejected band with a wide operating bandwidth is obtained by embedding an E shape slot in the rectangular radiation patch and its parameters studied in detail. The notched band is controllable by adjusting...
In this paper, a new method of the multibaseline interferometric SAR phase unwrapping based on the model of the optimum data vector is introduced. The method constructs the multibaseline optimal weighted joint data (MOWJD) vector by taking advantage of the coherence information of neighboring pixels in order to adaptively coregister the SAR images and then employ the projection of the joint signal...
A novel patch-shaped patch loaded slotline (PLS) to provide a band-rejection property with an improved Q factor is proposed in this paper. It has size of only 28% of conventional dumbbell PLS unit section and 72% of the conventional open-loop PLS unit section, while the Q factor is more than 10.5 times than dumbbell PLS and 3.3 times than the conventional open-loop PLS at the same resonant frequency...
This work describes an extension to the use of indirect holographic techniques for antenna measurements. Previous versions of this work have been restricted to the measurement of high gain antennas without reducing sample spacing and increasing measurement times. This work describes a technique whereby using both sum and difference signals from the complex near field and the reference signal cancellation...
In order to save the space of aerocraft, the conformal antennas can be adopted, which also donpsilat affect the dynamics performance. This paper discusses a kind of cylindrical conformal Yagi-Uda antenna and estimates its radiation characteristics. The proposed cylindrical conformal Yagi-Uda antenna is composed of five conformal dipoles, which is mounted on the surface of the cylindrical object in...
A Ka band Cassegrain monopulse antenna has been designed and measured. The tapered rod antennas are used as the feeds of the Cassegrain antenna because their blockage is small and their bandwidths are very wide. The measurements show that the gain of sum pattern is 28 dBi, the sidelobe levels of the sum pattern are less -15 dB, the null depths of the difference pattern are less then -25 dB and the...
Compared to the array antennas with the same distance, those with different distances can improve the directivity and avoid occurrence of high minor-lobes. In this paper, GA is used to optimize the minor-lobes. During the progress, the minor-lobes level is defined as the fitness function. The first null direction is estimated properly so that the modified factor is used to avoid the complication of...
Antennas receive the power from free space and transmit it to the loads. In this process, antennas are like power supplies with impedance. So the equivalent circuit method can be used to study receiver antennas. From the equivalent receiver circuit of dipole antennas, the relationship between dipole antennas as scatters and as radiators is found. The radar cross-section (RCS) expressions of resonant...
A hybrid method which combines the finite element and boundary integral methods (FE-BI) for simulating electromagnetic radiation of antennas is presented. The method not only can correctly model the boundary conditions, but also can deal with complex geometry and material structure. The matrixes formed from FEM are sparse, and the boundary integral method is applied to reduce the simulation complexities...
Electromagnetic wave propagation and scattering by the left- and right-handed material cylinder is investigated by incident wave. The schematic geometry of double-layered cylinders alternatively constitutive of left- and right-handed materials is also proposed. Furthermore, the distribution of the electric fields inside and outside the cylinder is calculated by numerical methods. Bizarre EM scattering...
A novel approach for transient analysis of coupled transmission line circuits is presented. While frequency domain response is obtained, it must be transformed to time domain response. The 1-domain modified numerical inversion Laplace transform (NILT) and 2-domain modified NILT are utilized for the time domain response. Then quotient-difference algorithm is used to provide higher speed of calculation...
The influence of dielectric layers on the transmission properties of FSS with cross slots was studied by using the simulation method. The model of the FSS, the simulation results and the experimental results of the template are given. The relation between the resonance frequency and the thickness of the dielectric layers, the curves of the transmission vs frequency of the varying dielectric layers...
In this paper, the MPSTD algorithm is applied to model the H-T junction in rectangular waveguide. The S parameters of the H-T junction are analyzed by MPSTD. The numerical results indicate that the MPSTD algorithm is accurate and efficient to analyze the H-T junction.
A novel circularly polarized microstrip helical antenna with broad impedance bandwidth and 3 dB axial ratio bandwidth is proposed based on traditional helical antenna. The helix is realized by connecting stacked multilayer microstrip circular arcs with vertical via holes. Details of the antenna analysis and design are described. Simulation results show that good radiation performance can be achieved.
This paper presents the microstrip antenna with triangular tuning stub which designed and simulated by using IE3D program. This antenna is designed for 50 Ohms impedance microstrip line for dual band frequency, 2.297-2.952 GHz and 5.138-6.051 GHz which supports WLAN communications coverage IEEE 802.11b/g (2.4-2.4835 GHz), IEEE 802.16a (5.15-5.35 GHz) and IEEE 802.16d (5.7-5.9 GHz). The bandwidth at...
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