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A fully functional internal DTV diversity antenna has been designed and tested. The proposed internal balanced dipole antenna was integrated with a DTV module in a notebook computer. The results demonstrate that a balanced dipole antenna for noise suppression and diversity reception enable high quality reception of a DTV signal even though we trade-off some antenna performance after packaging in notebook...
Low-sidelobe radiation patterns with good directivity can be generated by antennas consisting of a linear array of parasitic dipoles in front of a smaller linear array of active dipoles fed uniform voltages, a configuration that facilitates the task of feed network design. The fundamental effect of the parasitic array is to allow the length of the active array to increase by a factor of 2 or more,...
Designing HF communication systems to work in forested environments motivates a desire to understand the forest as a medium for radio wave propagation. At HF frequencies the forest is highly anisotropic because the most significant scatterers are vertical tree trunks. So, a reasonable first-order model of the forest is a grid of vertical scatterers. Using the Numerical Electromagnetic Code (NEC),...
Ultrawide-band (UWB) is a new technology that transmits very low energy levels broadband pulses allowing for short-range high-bandwidth communications. In some environments, UWB systems require the inclusion of band-rejection filters to avoid the possible interference from pre- established wireless local area networks (WLAN), allocated from 5.15 GHz to 5.825 GHz. Recently, the required band rejection...
In this paper, it was shown that the inverse discrete dipole method with far-field approximation yield results comparable to the ones obtained with complete-field solution. The application of the far-field approximation does have a significant impact on computation time, where a speedup of two-hundred percent was observed.
In this paper, few topics related to the near-field and far-field behavior of a vertically oriented antenna above a PEC ground plane is discussed. The very near-field is determined by the position where the wave impedance approaches free space impedance, and the phase of the wave impedance approaches zero. As one move further ahead the wave sphericity condition determines the transition from the radiative...
Conclusions In this paper, a phased array antenna (PAA) using crossed dipole antenna elements is examined. A partially driven array technique is used for the array antenna. From the analyzed results, it is shown that the element antenna has conical radiation pattern. Using the element antenna, the beam scanning characteristics of the PAA is investigated. It is found that this array antenna can scan...
A vertically folded dipole on a multi-layer circuit board is proposed. The two radiation arms are spread into two dielectric surfaces and connected through vias. It effectively reduces antenna area by half without decreasing the bandwidth. It also facilitates meandering the strip dipole and further reduces the antenna length. Examples are given to characterize the vertical two or three folded dipoles...
In this paper, a spherical-shaped, UHF RFID tag antenna with 3-axes polarization is proposed to detect information of the status of a liquid container by inserting it inside the liquid container, which would be beneficial for a patient management in a hospital. Fig. 1 shows an example of reading environment of RFID tag for liquid detection. Typically, it is hard for a tag antenna to be identified...
A design for a reconfigurable planar quasi-Yagi antenna with a folded dipole driver element is presented. Reconfigurability of the operating frequency of the antenna is achieved by changing the effective electrical length of the folded dipole, which is controlled by a varactor diode. The predicted operating frequency of the quasi-Yagi antenna can be continuously tuned from 5.6 to 7.6 GHz using a typical...
A design for a new quasi-Yagi antenna suitable for fabrication on low-cost, low dielectric constant materials such as LCP was developed by replacing the half-wavelength dipole driver element with a folded dipole. The input impedance of the folded dipole quasi-Yagi antenna and its resonance frequency may be tuned by properly adjusting the parameters of the folded dipole giving more freedom for optimization...
The mutual coupling between two broadside printed dipoles in stratified anisotropic dielectrics is evaluated using newly derived spectral domain immittance functions. It is shown that an increase in the permittivity in the layer below the dipoles in the direction of the optical axis can significantly increase the mutual coupling while an increase in the permittivity in the direction orthogonal to...
As is well known, an electric radiator field is divided conventionally into three regions: a near region (an induction region or Fraunhofer one), an intermediate region (or Fresnel one) and a far region (a radiating one). Until recently radiators properties in a near region arouse a weak interest among antennas creators. But now these questions importance increased in view of problems of facilities...
Ultra-wideband (UWB) antennas have gained great interest since the US Federal Communication Commssion (FCC) released the generic admission for UWB in the frequency band between 3.1 GHz-10.6 GHz in 2002. In Europe a similar regulation standard with a reduced bandwidth (6 GHz-8.5 GHz) is available. Due to the inherent wide bandwidth, communication systems with a high data rate and high resolution imaging...
In this article, we propose a spherical shell-core structure which is able to achieve arbitrarily large directivity. The structure is obtained from coordinate transformation. A small antenna can be projected to free space with a large dimension, which subsequently leads to a large directivity.
The far-field radiation of a Hertzian dipole for a two-layered gyromagnetic medium has been investigated using the dyadic Green's function. For this purpose, the symmetric property of DGFs has been employed to calculate the dyadic Green's function when an impulse source is placed above the gyromagnetic slab. After obtaining the far-field approximated DGFs, radiation fields are found for a dipole antenna...
A tri-band monopole antenna is presented, which employs metamaterial loading on a defected ground plane in order to create an antenna covering the WiFi and WiMAX bands. The measurements show monopolar-like radiation patterns at 3.50 GHz and 5.50 GHz and orthogonal dipolar-like patterns at 2.44 GHz. High radiation efficiencies are obtained in all three bands, despite the small size of the antenna,...
In this paper, a planar inverted miniaturized ultra high frequency E antenna, with high gain will be discussed. This paper will present the design of the microstrip antenna, its development and performance based on the measured results. The shape of the antenna is similar to the inverted alphabet E, which is why the antenna is referred as E antenna. The operating frequency of the antenna is 868 MHz...
The path loss between insulated dipole antennas in homogeneous human muscle tissue is investigated at 2.457 GHz and an in-body path loss model is derived. Simulations using the FDTD and the MoM methods show excellent agreement. Also, the low values of the deviations demonstrate an excellent agreement between the simulations and models.
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