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Measurements of Wearable Systems and Antennas
Published in Albert Sabban, Novel Wearable Antennas for Communication and Medical Systems, 2017
A radiation pattern is the antenna radiated field as a function of its direction in space. The radiated field is measured at various angles at a constant distance from the antenna. The radiation pattern of an antenna is defined as the locus of all points where the emitted power per unit surface is the same. The radiated power per unit surface is proportional to the square of the electric field of the electromagnetic wave. The radiation pattern is the locus of points with the same electrical field strength. Usually the antenna radiation pattern is measured in a far field antenna range. The antenna under test is placed in the far-field distance from the transmitting antenna. Due to the size required to create a far-field range for large antennas near-field techniques are employed. Near-field techniques allow measurement of the fields on a surface close to the antenna (usually 3–10 wavelengths). The near-field measurements are transferred to far field by using a Fourier transform.
Basic Antenna Parameters and Definitions
Published in Victor Rabinovich, Nikolai Alexandrov, Basim Alkhateeb, Automotive Antenna Design and Applications, 2010
Victor Rabinovich, Nikolai Alexandrov, Basim Alkhateeb
Far zone antenna radiation pattern or far zone directionality is the parameter that determines angle dependence of the power radiated (or received) by an antenna versus angle coordinates θ and φ shown in Figure 2.1. The IEEE standard for a spherical coordinate system determines that angle θ is measured from the z-axis (zenith). The azimuth angle φ is measured from the projection of the radius vector r¯ to the xy (horizontal) plane with φ = 0 at the x-axis increasing counterclockwise. Radiation pattern is a measure of the capability of an antenna to capture signals more favorably in one angle direction than another. Radiation pattern F(θ, φ) can be presented as a sum of two orthogonal components (Reference [1], pp. 38, 44).
Radiation Mechanism
Published in Ahmad Shahid Khan, Saurabh Kumar Mukerji, Electromagnetic Fields, 2020
Ahmad Shahid Khan, Saurabh Kumar Mukerji
The “radiation pattern” also called directional pattern is the graphical representation of field distribution in space due to radiation from an antenna. It is a function of direction or space coordinates. The form of this pattern is often referred to as a beam. This beam may be very narrow (pencil beam), very wide (fan beam), omni, or an arbitrary shape. A radiation pattern may comprise a single beam or multiple beams. In radar, these beams may be mechanically or electronically steered.
Design and fabrication of reconfigurable, broadband and high gain complementary split-ring resonator microstrip-based radiating structure for 5G and WiMAX applications
Published in Waves in Random and Complex Media, 2022
Shobhit K. Patel, Sunil P. Lavadiya, Juveriya Parmar, Kawsar Ahmed, Sofyan A. Taya, Sudipta Das
The authenticity of the proposed design structure is analyzed to compare the results of simulated and measured structures. The measurement is carried out for simple patch structures; copper-loaded metamaterial, and liquid-loaded metamaterial design structures. Figure 9 represents the comparison between simulated and measured design gain plots for different switching conditions. The radiation pattern represents the electromagnetic beam behavior in a specific direction. The comparison among the measured and simulated radiation patterns for different switching conditions is represented in Figure 10. The co-polarization and cross-polarization plot for different switching conditions is presented in Figure 11. All Electromagnetic waves are made up of electric-field (E-Field) and Magnetic fields (H-field). The H-field is measured in Amps/Meter since the H-field has a magnitude and direction. The dielectric substrate may be viewed as a general transmission medium with transmission line theory and cavity model theory. An H-field occurs around the patch radiator in the substrate and atmosphere [44,45].
Minimization of side lobe level of non-uniformly spaced concentric elliptical array antennas for a desired value of first null beam width in vertical and horizontal planes
Published in Electromagnetics, 2020
Antennas have various applications where a specific radiation pattern is required for communication. The preferred radiation pattern can be reached by setting up an assembly of radiating elements in various kinds of geometrical configurations, which is known as array of antenna (Balanis, 2005). Restricted main beam and nulls at desired places in the pattern are always desirable in any type of long-distance communication. Antenna arrays can achieve desired radiation pattern for a specific application without enlarging the size of a single antenna (Neyestana et al. 2008; Shihab et al. 2008). Recently, elliptical array antennas have become very popular for its several advantages over linear and circular array antennas. Different elliptical array antenna structures have been considered and optimization is performed using various algorithms (Ahmidi, Neyestana, and Dawes 2008; Dib, Amaireh, and Al-Zoubi 2019; Lema, Tesfamariam, and Mohammed 2016; Rao, Ankaiah, and Cheruku 2016; Sadeghzadeh et al. 2008; Sainath, Chaitanya, and Raju 2017; Sharaqa and Dib 2013; Zare 2012).
Triple Band Compact Monopole Antenna for Applications Like Bluetooth, WiMAX and WLAN
Published in IETE Journal of Research, 2021
Kailash Chandra, Mahendra Kumar, Madhur Deo Upadhayay
Radiation pattern of the antenna describes the radiated power variation in a three-dimensional (3D) space. Monopole antenna has an omnidirectional radiation pattern at its resonance which is bidirectional in E-plane and circular in H-plane. E-plane radiation patterns of the antennas in design-A and B for each resonant frequency are shown in Figure 6. Figure 6(a) shows that for design-A at a higher resonant frequency of 6.12 GHz, the radiation pattern is degraded, while at lower resonance at 2.66 GHz pattern is similar to the conventional dipole pattern of figure of eight. The reason behind this pattern degradation at higher resonance is the higher-order mode and so this resonance is not taken into consideration. Cap-shaped ground plane and modified feeding technique in Design-B not only creates a second resonance near to the first resonance but also shifts the higher-order mode far away from the first two resonant frequencies. The radiation patterns at center frequencies of the dual bands in Design-B have similar kinds of nature without any pattern degradation. Patterns show a bidirectional radiation with maximum along φ = 0° and φ = 180° and have null in the patterns occur at φ = 90°. Antenna radiation patterns (E-plane and H-plane) at three frequencies are checked in a fullwave simulator. Patterns show characteristics identical to conventional monopole antennas with good co- to cross-polarization isolation at each resonant frequency. The minimum cross-polar value is 15.9 dB at 5.86 GHz and the maximum value is 33.16 dB. The cross-polarized (XPOL) discriminations at each resonant frequency in both planes and half power beam widths (HPBW) are shown in Table 5.