نتایج جستجو برای: directive antenna
تعداد نتایج: 56676 فیلتر نتایج به سال:
چکیده در دهه های اخیر با رشد چشمگیر شبکه های بیسیم اقتضایی امکان دسترسی به شبکه، بدون نیاز به کنترل کننده مرکزی و زیر ساخت سیمی فراهم شده است. تقاضا برای دسترسی به اطلاعات در هر زمان و مکان، ضرورت توسعه این گونه شبکه ها را غیر قابل انکار می نماید. این توسعه بدون افزایش ظرفیت شبکه و استفاده بهینه از پهنای باند امکان پذیر نمی باشد. علاوه بر محدودیت پهنای باند که در تمام شبکه های بیسیم وجود دارد،...
Loop antennas of circumference greater than a wavelength are generally known to have a good directive radiation pattern. However, for use in UWB applications, the variation of the radiation pattern with frequency must also be taken into account. Besides a good wideband radiation pattern, the impedance bandwidth of the antenna is also very important. The quality of a transmitted and received UWB...
A new metasurface superstrate structure (MSS)-loaded dual band microstrip line-fed small patch antenna is presented in this paper. The proposed antenna was designed on a ceramic-filled bioplastic sandwich substrate with a high dielectric constant. The proposed 7 × 6 element, square-shaped, single-sided MSS significantly improved the bandwidth and gain of the proposed antenna. The proposed MSS i...
In recent communication systems side lobe level reduction has become one of the important issue. For applications like digital beam forming it is one of the important factor because it reduces the effect of interference arriving outside the main lobe. This reduction in the interference increases the capacity of the communication systems. This paper presents the different methods for reducing th...
In this paper a study of the directive gain enhancement obtained using a dielectric lens placed in the near field of radiating elements is discussed. The design and results of a single element patch antenna along with hemispherical and spherical lens radiating in C-band are detailed. The design has been accomplished using the 3D finite-element-method (FEM) electromagnetic EM simulator, HFSS, is...
This paper proposes a double negative metamaterial surface as a superstrate for a multilayer cylindrical dielectric resonator antenna (MCDRA). The aim is to achieve a broadband and high gain Electromagnetic Band Gap (EBG) antenna that can be used in harsh propagation areas to satisfy all the requirements for the 60GHz wireless communications offering a bandwidth of 7GHz in the unlicensed ISM ba...
In this paper, the analysis of a modified E-shaped patch antenna is presented. The purpose of the modification over the original Eshaped structure is to accommodate the operating frequency band and signal bandwidth requirements of the Ultra Wideband (UWB) wireless system. Simulation results show that the modified E-shaped has fulfilled the frequency band and signal bandwidth requirements of the...
Directive antenna array with reduced side lobe level can be obtained using thinned array. This paper describes the design of planar thinned array using Hadamard matrix-like arrangement. Here ‘on’ and ‘off’ states of the antenna elements are arranged based on Hadamard Matrix and inter-element spacing in x and y-directions are varied and then genetic algorithm is used to optimize lowest side lobe...
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