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Antennas for Wearable 5G Communication and Medical Systems
Published in Albert Sabban, Wearable Systems and Antennas Technologies for 5G, IOT and Medical Systems, 2020
The wire loop antenna has very low radiation efficiency. The amount of power radiated is a small fraction of the input power. The antenna efficiency is around 0.01%, −41 dB. The ratio between the antenna’s dimension and wavelength is around 1:100. Small antennas are characterized by radiation resistance Rr. The radiated power is given by I2Rr, where I is the current through the coil. Remember that the current through the coil is Q times the current through the antenna. For example, for current of 2 mA and Q of 20, if Rr = 10−3 Ω, the radiated power is around −32 dBm.
Wearable Printed Antennas for Wireless Communication Systems
Published in Albert Sabban, Novel Wearable Antennas for Communication and Medical Systems, 2017
The wire loop antenna has very low radiation efficiency. The amount of power radiated is a small fraction of the input power. The antenna efficiency is around 0.01%, −41 dB. The ratio between the antenna's dimension and wavelength is around 1:100. Small antennas are characterized by radiation resistance Rr. The radiated power is given by I2Rr, where I is the current through the coil. Remember that the current through the coil is Q times the current through the antenna. For example, for a current of 2 mA and Q of 20, if Rr = 10−3 Ohm, the radiated power is around −32 dBm.
Communications
Published in Diego Galar, Uday Kumar, Dammika Seneviratne, Robots, Drones, UAVs and UGVs for Operation and Maintenance, 2020
Diego Galar, Uday Kumar, Dammika Seneviratne
A wire antenna is simply a straight wire of length ë/2 (dipole antenna) and ë/4 (monopole antenna), where ë is the transmitted signal wavelength. A wire antenna can be a loop antenna, such as circular loop, rectangular loop, etc. Basically all vertical radiators are in wire antenna categories. A whip antenna is the best example of a wire antenna (Dhande, 2009).
Coplanar Waveguide-fed Electrically Small via-less Antenna for Dual Band Applications
Published in IETE Journal of Research, 2021
Vivek Rajan, Prakash Karavilavadakkethil C., Vinesh Puthiyapurayil V., Mohanan Pezholil, Vasudevan Kesavath
As a result of the increasing demand for portability and compactness in wireless technology, the need for electrically small antennas is growing. To obtain fundamental radiation performance characteristics as an electrically small antenna, lots of designs have been reported with several different operating systems, such as loops, semi loops, folded and meandered dipoles, resistive and reactive loading, using passive components and by metamaterial structures also. For example, a loop antenna with a loading element to achieve the small size is reported in [1]. In [2], two split-ring resonators and a small ring structure with an inbuilt capacitor structure are presented, in which the total electrical length is reduced by the additional capacitance obtained from the inbuilt capacitor structure. A passive component like a capacitor loaded loop antenna is demonstrated in [3] and a chip inductor loaded electrically small antenna in [4]. Folded dipole antenna employing air-core inductors to reduce power loss, hence radiation characteristics improvement of ESA is reported in [5]. A spherical split ring resonator with a dual-polarized wire cage for an electrically small antenna operation is studied in [6].
Micro-strip antenna with high bandwidth, cone pattern, circular polarization, and slit
Published in Electromagnetics, 2019
Jafar Khalilpour, Milad Nosrati
The studies on the micro-strip antennas with cone patterns introduced a new compact patch antenna which forms a cone pattern (Ravipati 2004). A slit has been used in this antenna which has led to a decrease in the antenna dimensions about 50%, and then, a patch antenna with cone pattern and circular polarization which uses hybrid-fed mechanism is introduced (Lau and Luk 2006). In the construction of this antenna, a pair of L-shaped probes and slits that are connected to the feeding network has been used to create a circular polarization along the horizon. The patch antenna is also kept in the air by metal legs. A new method was used for the antenna with cone pattern and circular polarization (Liu et al. 2011). In this method, the antenna consists of four parts including the plane loop antenna, feeding network, reflector, and a horizontal monopole.
Electromagnetic radiation response from cement paste: a tool to monitor hydration and extent of deformation
Published in Journal of Sustainable Cement-Based Materials, 2019
Amit Kumar, Sumeet Kumar Sharma, Vishal S. Chauhan, Rajeev Kumar
One Rohde & Schwarz (Hameg) make digital storage oscilloscope (DSO) HMO2524 having specification 250 MHz/2.5 GSa/4 MB was used to capture the EMR signals. A loop antenna which was used to record the signals was made up of copper strip. For antenna a rectangular strip of length 150 mm and width 18 mm was cut from the copper sheet of thickness 0.1 mm. Then, the rectangular copper strip was folded into a circular loop having radius of 23 mm and was placed around the sample to capture the EMR signals emitted from the sample. One end of the measuring probe of the oscilloscope was connected to the antenna and another one was grounded. With the help of non-contact loop antenna and oscilloscope, voltage generated during impact was recorded.