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Scattering Polarimetry
Published in Yoshio Yamaguchi, Polarimetric SAR Imaging, 2020
This equation is known as the Friis transmission equation and it relates the power Pr (delivered to the receiver load) to the input power of the transmitting antenna Pt. The term (λ4πr)2 is called the free-space loss factor, and it takes into account the losses due to the spherical spreading of the energy by the antenna. This equation is the basis for communication systems. In this configuration, the receiving power decreases as r−2 with increasing r.
Radio Frequency Identification Systems and Sensor Integration for Telemedicine
Published in Fei Hu, Qi Hao, Intelligent Sensor Networks, 2012
Ajay Ogirala, Shruti Mantravadi, Marlin H. Mickle
The Friis transmission equation relates the power transmitted by the transmitting antenna to the power received by the receiving antenna as a function of the antenna gain, frequency of operation, antenna reflection coefficient, antenna polarization, and medium. It is important to understand that the entire RFID system can operate as designed only if the received power (at interrogator or tag) is adequate to decipher. As clearly equated by the Friis equation, this received power is highly sensitive to the polarization of the interrogator and tag antennas. While the available literature portrays the varied applications of RFID, the reader has to note that all that is possible in theory and textbooks cannot be practiced due to current limitations in the manufacturing process of RFID tags that directly affect the cost and dimension of available tags.
Proactive flow control using adaptive beam forming for smart intra-layer data communication in wireless network on chip
Published in Automatika, 2023
Dinesh Kumar T.R., Karthikeyan A.
Let Pt be the transmitting antenna's output power, and (t, t) denote the receiving antenna's relative angle. Similarly, place a receiving antenna at distance R with a relative angle (r, r) to the sending antenna. The receiving antenna's transmitting power, Pr, is calculated using Friis’ transmission equation [23]. The Friis transmission equation, which is valid for R > 2D2/, can be used to calculate the fraction of transmitting power that reaches the receiving antenna's terminal, Pr, where D is the antenna's greatest dimension (axial length in this example) and is the wavelength 1. where et and er are the efficiencies of the transmitting and receiving antenna, respectively. The directivities of the transmitting and receiving antenna are Dt and Dr, respectively. λ is the effective wavelength. Antenna orientation and directivity play an important role in optimizing the energy efficiency in WiNoc. For wirelessly transmitting a bit of information from transmitter “i” to receiver “j”, the energy consumed is: where η is the transmitter efficiency. Considering Equations (3) and (4), Equation (5) can be written as
Implantable Antenna Design Based on Gosper Curve Fractal Geometry
Published in IETE Journal of Research, 2023
Rajeev Kumar, Surinder Singh, Ajay Pal Singh Chauhan
The prototype of proposed Gosper curve fractal implantable antenna is fabricate on Rogers RO 3010 laminate (ϵr = 10.2, tanδ = 0.0023) of thickness (h = 10 mil) feed through RG178 50 Ω coaxial cable attached with 3.5 mm female connector. The antenna layers have been bonded with the help of araldite adhesive. The fabricated prototype and measurement setup are shown in Figure 10. For experimental investigation, the antenna is placed inside the human tissue mimicking liquid phantom [18]. The phantom has been mainly prepared by mixing sugar and salt in water, which contains water-sugar ratio of 37:50 and salt 1 gm per 100 ml of solution. The obtained permittivity and the conductivity are 56.3 and 0.67 S/m, respectively at 402 MHz. To examine the antenna’s credibility, the proposed antenna design has been analyzed with two different numerical solvers (HFSS and CST microwave studio) in which the max gain of −35.6 dBi has been achieved. The gain of the proposed prototype antenna is measured with the help of the three-antenna technique using Friis transmission equation [17]. Log periodic dipole antenna (LDPA) is used as a reference and transmitting antenna. The realized measured gain of the prototype is achieved with −39.58 dBi. Figure 11 shows the simulated and measured reflection coefficient of the proposed Gosper fractal antenna design. The experiential measurements have been carried out with the help of Keysight PNA-L N5232B network analyzer. Figure 12 shows the radiation pattern behavior of the proposed antenna design with good harmony in results. As the antenna is linearly polarized, only co-polar results have been measured. The simulated and measured gain responses are shown in Figure 13. The result shows a good agreement with small resonance shift, which may vary due to the variation in simulated and measured permittivity and conductivity. Even the presence of glue can also affect the antenna performance. Still, the overall performance of an antenna is closer with that of the numerical design. Table 3 shows the performance comparison of proposed antenna with earlier reported literature.