The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
The scattering characteristics of artificial dielectric made of a finite cascade of planar lattices of printed disks is analyzed using a self-consistent theory of interaction between the small metallic disks and the associated electromagnetic fields. Previous analyses based on the same theoretical technique did not include the effect of the induced magnetic dipoles; only the induced electric dipoles...
The objective of our work is to study the potential influence of non-thermal power level 60GHz radiation on the artificial biological membranes. Different types of characterization of lipid single layers are used: 1) measurements of superficial tension by Wilhelmy method and 2) observation by atomic force microscopy (AFM). Two major phospholipid constituents of biological membranes are considered:...
finite dielectric substrate influence on UWB antenna performance is investigated theoretically. The computational model is built based on the volumetric mixed-potential integral equation and takes into account the finite size of the substrate. Influence of the substrate size on the antenna reflection coefficient, the antenna gain and the radiation patterns have been investigated.
Design and simulation of a smart antenna system for 802.11a wireless LAN is proposed. The main advantage of this design is that it is applicable as an external antenna module, regardless of the other parts of the system i.e. the WLAN card. The antenna is a 3×3 planar array of rectangular patches, in the 5.15GHz ∼ 5.35GHz band. The antennas are probe-fed so that they can be connected to separate phase...
In this theoretical study eigenfields of a periodical arrangement of longitudinally directed dipoles on an infinite plane are considered. The dipoles are small wire antennas, which are close to each other forming an infinite dipole array. The coupling between the antenna elements is taken into account. An analytical solution for waves propagating along this dipole array structure is considered. Radiated...
Application of the shielded loop antenna as a replicating sensor for transient antenna measurements is discussed. Different sensor designs, measurements schemes and calibration curves are presented. It is shown that the shielded loop antenna is a simple (both in development and application) and reliable ultra-wideband sensor for antenna measurements, in particularly in the near field.
In this paper, a new configuration of EBG resonator antennas with an adjustable directivity is proposed. The tunability is obtained by integrating an active grid inside the Fabry-Perot resonator. The input impedance and radiation characteristics of 2D and 3D structures with various Q-factors are investigated numerically using the Finite-Difference Time-Domain (FDTD) method. Their performance and limitations...
A conducting-polymer patch antenna was fabricated by a screen-printing technique. Polyaniline (Pani) films of conductivity 6000 S/m, permittivity 6000 and thickness 100 µm have been used as a radiating patch. HFSS was used as a design tool to validate the experimental measurement of the Pani-patch antenna. Measured and simulated results of the resonant frequency, return loss, gain, bandwidth and radiation...
Mutual coupling, among other effects, causes the element patterns in an antenna array to be different. In the practical adaptive use of the array identical element patterns are usually expected. Linear pattern correction with matrix multiplication can be used to correct the array element inputs/outputs. In this paper, a multiport model for a microstrip array and a method to find the input circuit...
A compact radiating structure equivalent to a magnetic dipole has been designed and measured. Radiation is horizontally polarised, omni-directional, with a low cross polarisation level. In this work, several techniques of miniaturisation have been used in order to achieve a 0.3 λ0 squared planar antenna with a 8.7% bandwidth.
Single patch antennas were investigated by many researchers. To change the resonance frequency slots are added to the patch. In this paper we utilized Genetic Algorithm (GA) linked with Finite Difference Time Domain (FDTD) to optimize single patch for wide bandwidth. The patch surface was divided into a number of cells. At each iteration of GA, some specified randomly selected cells were cut and the...
The concept of beam scanning with an EBG Fabry-Perot resonator has been studied in this paper. Using an analytical model, we first show that beam scanning can be achieved by the influence of the frequency, the reflection coefficient of mirrors or the cavity thickness.
The capacity of a transmitting system to concentrate the radiation in a desired direction is well described by means of the directivity. Its knowledge is very important when using the radiating structure for specialized and high-performance communication links. The computation of the total radiated power, which is obtained by integrating the radiation intensity on the far-field (FF) spherical surface,...
This paper presents omnidirectional metallic EBG (Electromagnetic Band Gap) antennas. The composition of the structure is explained and some typical radiation patterns in the principal planes of the antenna are shown. The performances of the antenna in terms of directivity and radiation bandwidth are defined function of the EBG material composition and of the height of the antenna. Finally, a comparison...
This paper describes the research work at the Radio Laboratory of Helsinki University of Technology concerning millimetre and submillimetre wave antenna technology: development of new antenna designs and, especially, development of antenna measurement techniques for electrically large, high-gain antennas. Also, development work of some related fields in millimetre wave instrumentation is presented.
An offset dielectric-loaded flat reflector antenna has been designed and realized for submillimeter wavelengths. The antenna has an aperture size which provides a compromise between a high directivity and a reasonable size for a test object in the development work of antenna measurement techniques dedicated for high-gain antenna tests. The diameter of the dielectric loading on top of the flat main...
In this paper, we present new method for the modeling of printed strip gratings. Our general approach for finite perfectly electric conducting (PEC) strip gratings printed on a dielectric substrate with a PEC ground plane is based on the parametric representations of the integral and pseudo-differential operators and Method of Discrete Singularities (MDS). Diffraction problem is first reduced to hypersingular...
This paper presents an innovative microwave imaging technique suitable for NDT/NDE applications. To reduce the number of problem unknowns as well a the computational load by improving the convergence rate of the process, the available a-priori information is exploited by introducing a computationally-effective procedure for the prediction of the electric field based on the updating Sherman-Morrison-Woodbury...
Radio Frequency Identification (RFID) is one of most efficient way for traceability. This last one is compulsory for several applications such as domestical animals or advised in other cases for furnitures tracking for instance. Many standards with different frequencies already exist. Our interest lies on solutions at 2.45GHz [1,2], in particular on low-cost antennas and RFID-chip adaptation on it.
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.