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Ultra-Wideband Antenna Technology
Published in James D. Taylor, Introduction to Ultra-Wideband Radar Systems, 2020
P. R. Foster, J. Doss Halsey, Malek G. M. Hussain
The electrical boresight must be known by a radar so that the angular direction in which the target lies may be found. In narrowband systems, electrical boresight is the tracking axis or the angle at which the largest signal from the antenna appears, and this axis is often the line at right angles to the antenna aperture. For instance, the vertex line is the electrical boresight for a paraboloidal reflector with a feed at the focus. For a horn antenna fed with the fundamental mode, the electrical boresight is the axis of the horn. For an array antenna, the electrical boresight is the line about which the radiation pattern in amplitude and phase is most symmetric. This last definition is a generalized statement that can be used for all situations.
Mounting Multiple Lens Assemblies
Published in Paul Yoder, Daniel Vukobratovich, Opto-Mechanical Systems Design, 2017
Two individually rotatable optical wedges in the 7 mm (0.28 in.) diameter-collimated input laser beam are used manually to boresight that beam to a reticle pattern in the visual periscope prior to a mission. The worm gear and control knob of one wedge may be seen on the right in Figure 5.13. As shown in Figure 5.14, a single-element negative lens diverges the beam as it enters the small piggyback prism cemented to an unaluminized central area on the fold prism hypotenuse. This beam refracts through the various lens elements of the assembly and emerges from the entrance aperture of the objective as a nominally collimated laser beam of 70 mm (2.8 in.) diameter.
Novel corrugated rectangular dielectric resonator antenna with wide half power beam width
Published in Electromagnetics, 2023
A prototype of the proposed DRA is constructed, as demonstrated in Figure 2. Rogers 6010 board with a standard thickness of 1.27 mm is used to fabricate the antenna. Figure 3 illustrates the measured and simulated reflection coefficients of the fabricated DRA. As shown, a broad impedance bandwidth of 23% (3.8–4.8 GHz) is achieved. Also, measured results are in a good agreement with the simulated ones. The boresight gains obtained from simulation and measurement are illustrated in Figure 4. It ranges 0.9 dB to 5 dB within the entire band. Due to the wide HPBW of the radiation pattern, the boresight gain of the antenna is lower than the typical values reported in the literature. It is normal for the gain of an antenna to decrease as the Half Power Beam Width (HPBW) is widened. This is because the gain of an antenna is a measure of its ability to focus its radiated power in a particular direction. When the HPBW is widened, the radiated power is spread over a larger area, resulting in a decrease in gain.
Trapezium backed dual circularly polarised hepta-band monopole antenna
Published in International Journal of Electronics, 2022
Priyanka Choudhary, Deepika Sipal, Sudeep Baudha
Figure 18 represents XZ plane and YZ plane measured and simulated radiation pattern, respectively. The radiation patterns are contributed by E slot arms laid on XY-plane. These also indicate direction of boresight radiation pattern. The electric field on slots has Eθ and Eϕ components of accounting for z and y components. Whereas current on radiator and ground mainly flows in x-direction. The XZ-plane is nearly omnidirectional and YZ-plane is roughly elliptical in shape. The simulated and measured results confirm that the proposed antenna exhibits a working CP bandwidth (|S11|< −10 dB & AR <3 dB) covering IEEE802.15, IEEE802.11, Zig bee, PAN, WLAN, WiMAX, RLAN, FWA, Satellite Communication, Short Range RADARs and Radio applications. It is observed that the proposed antenna has RHCP in the direction of main beam (θ = 0°) at 4.2 GHz.
A low profile miniature RFID tag antenna dedicated to IoT applications
Published in Electromagnetics, 2019
Bilal Aslam, Muhammad Kashif, Muhammad Awais Azam, Yasar Amin, Jonathan Loo, Hannu Tenhunen
Figure 9a shows the reflection coefficient plot of the tag antenna for different mounting platforms. The frequency band is shifted to either a lower frequency or a higher frequency depending on the permittivity of the mounting object. However, the −10 dB frequency points lie more or less within the microwave band. Figure 9b presents the boresight tag antenna gain over the band of interest. Figure 9c compares the boresight read range of the tag antenna at 2.45 GHz in different environments including the free space. The boresight gain and the read range of the tag antenna increases on the different platforms in comparison to the free space owing to an improvement in the directivity and conservation of the reflection efficiency. The extent of improvement is dictated by the dielectric loss tangent of the platforms. The results are computed from Equation 1 utilizing a reader EIRP of 4 W. Figure 10 depicts the two dimensional and three dimensional radiation patterns of the tag antenna in free space and on different mounting platforms. The free space radiation pattern is donut-shaped indicating a wide coverage area. The radiation pattern is deformed upon mounting on different platforms implying a reduction in the coverage area. Maximum deformation is observed for water that has the largest dielectric loss tangent of all the platforms. However, despite the deformation, maximum radiation energy is concentrated in the main beam.