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Vehicular Smart Antenna
Published in Rajveer S. Yaduvanshi, Gaurav Varshney, Nano Dielectric Resonator Antennas for 5G Applications, 2020
Rajveer S. Yaduvanshi, Gaurav Varshney
DR of dimension rectangular 12 × 12 × 12.4 mm at the resonant frequencies fr = 24 GHz, with two sides equal (a = b), RDRA (εr = 10). Lst = 30 mm, Wst = 30 mm, Wsl = 1 mm, Lsl = 5 mm RDRA has been fabricated and mounted on a FR4 (εr = 4.4 and tanδ = 0:0019). Substrate thickness is 1.6 mm and micro strip feed line width was set to have 50 ohm and ground plane 30 × 30 mm2. Higher mode (TEy117, based on aspect ratio and slot position) has been excited into RDRA. Y indicates that h field is propagating in the y direction, while excitation field has been applied orthogonal, hence along the x direction. An angular rectangular strip placed on top of DRA introduces circular polarization. LHCP/RHCP will depend upon which field is dominant. Undesired modes can be suppressed using defected ground structure concepts. Circular polarization eliminates the requirement of line of sight and multipath fading to establish communication. The ground dimensions are taken more than DRA as given below:
Optical Nanolithography
Published in Bruce W. Smith, Kazuaki Suzuki, Microlithography, 2020
Polarized radiation results as the vibrations of a magnetic or electric field vector are restricted to a single plane. The direction of polarization refers to the electric field vector that is normal to the direction of propagation. Linear polarization exists when the direction of polarization is fixed. Any polarized electric field can be resolved into two orthogonally polarized components. Circular polarization occurs when the electric field vector has two equal orthogonal components, causing the resultant polarization direction to rotate about the direction of propagation. Circular polarization with a preferred linear component is termed elliptical polarization. Unpolarized radiation has no preferred direction of polarization.
Fundamentals of Ocean Optics
Published in Victor Raizer, Optical Remote Sensing of Ocean Hydrodynamics, 2019
In classical optics, polarization is defined as the orientation of electric field (E-field) of an electromagnetic wave (Born and Wolf 1999; Hecht 2017). Polarization of light in general is described by an ellipse. Two special cases of elliptical polarization are linear polarization and circular polarization. The case when the electric field always lies in the same plane is called linear polarization; the case when the electric field rotates while propagating is called circular polarization. In our brief description, we refer to books (Schott 2009; Collett and Schaefer 2012).
Circularly Polarized Parasitic Strips Loaded Broadband Printed Antenna for Sub-6 GHz (n77/n78/n79) Domain
Published in IETE Journal of Research, 2023
M. N. Manjunath, Ajay Kumar Dwivedi, Nagesh Kallollu Narayanaswamy, Anand Sharma, Vivek Singh
Circular polarization is produced by two electric field components (horizontal (EX) and vertical (EY)) of identical amplitude but 90 degrees out of phase with one another. The surface current distribution of the proposed model without parasitic strips is shown in Figure 8(a). It can be seen in Figure 8(a) that the components of the horizontal surface current in the ground plane are going in the opposite direction. As a result, in the far-field scenario, the horizontal radiation is negligible as the power is canceled out. However, it can be seen in Figure 8(b), asymmetric parasitic strips placement around the feed line produces two orthogonal currents, one horizontal (JX) and one vertical (JY). Strong EX and EY components are generated as a consequence of the currents produced on the strips. At the same time, the ground plane's current distributions are also changed because of the parasitic strips’ asymmetrical orientation.
Micro-strip antenna with high bandwidth, cone pattern, circular polarization, and slit
Published in Electromagnetics, 2019
Jafar Khalilpour, Milad Nosrati
Nowadays, micro-strip patch antennas are more commonly used due to lightweight, low cost, and the ability of integration with Low Noise Amplifier (LNA) and Solid State Power Amplifier (SSPA) electronic circuits. The circular micro-strip patch antenna has been used in the current study in which the dominant mode is TM11, with TM21 and TM31 as other important modes. It should be noted that the stimulation of the antenna in the higher modes requires more precise adjustment in some of the basic parameters of the antenna, since in the modes except dominant, there are noise effects such as power reactance, while in the higher modes, the antenna has radiation pattern which is equal to zero on the direction of broadside and has the main lobe in other angles. The circular polarization is needed since the relative rotation of the antenna in some applications such as satellite communications is required. Also, circular polarization and stimulation of the antenna make the antenna construction more difficult because many parameters of the antenna must be adjusted precisely. In order to enhance the patch antenna with circular polarization, the signal is divided into two equal parts, one feed in the horizontal direction and another one in a vertical direction.
A compact CPW-fed wideband slot antenna with reflector for wireless communication
Published in Electromagnetics, 2019
Amrita Gorai, Bappadittya Roy, G.K. Mahanti
Figure 3 shows the circular polarization of the antenna with a 3-dB axial ratio bandwidth of 1.18 GHz (5.11 GHz to 6.29 GHz). Circularly polarized antennas send and receive signal in all planes and so the strength of the signal is not lost, but it is transferred to a different plane and are still thereby utilized. The problems of absorption, multipath fading, and inclement weather are solved to a great extent due to circular polarization. Figure 4 depicts the plots of the peak gains of the proposed antenna. The gain is between 2 and 6 dBi in the lower band frequency region. The maximum gain is achieved at 9.5–10 GHz frequency.