INPUT IMPEDANCE AND RADIATION EFFICIENCY CHARACTERISTICS OF VLF TRAILING-WIRE ANTENNAS AND VLF SIDE-LOADED TRANSMISSION-LINE ANTENNAS

1963 ◽  
Author(s):  
H. D. Wade
Keyword(s):  
Transmission Line ◽  
Input Impedance ◽  
Radiation Efficiency ◽  
Wire Antennas

scholarly journals Simulation of Normal Incidence Sound Absorption Coefficients of Perforated Panels With/Without Glass Wool by Transmission Line Parameters in a Two-Port Network

2016 ◽  
Vol 44 ◽  
pp. 123-130
Author(s):  
Takayoshi Nakai
Keyword(s):  
Transmission Line ◽  
Input Impedance ◽  
Thermal Conduction ◽  
Sound Absorption ◽  
Sound Propagation ◽  
Viscous Friction ◽  
Normal Incidence ◽  
Glass Wool ◽  
Absorption Coefficients ◽  
Transfer Function Method

This paper describes simulation of normal incidence sound absorption coefficients of perforated panels by transmission line parameters in a two-port network. Maa and Sakagami have investigated micro perforated panels, MPP. But their theories can treat only near 1 % perforation rates of perforated panels with back cavities. If sound propagates as a plane wave, sound propagation can be represented as transmission line parameters in a two-port network. Perforated panels, back cavities, and glass wool absorption materials are represented as matrix of transmission line parameters, respectively. Transmission line parameters of a perforated panel with a back cavity are calculated as multiplication of their matrices. An input impedance can be calculated from the transmission line parameters. A normal incident absorption coefficient is calculated from the input impedance. Holes of the perforated panels have losses of viscous friction and thermal conduction at their walls. Simulations are done in the condition of 0.25 mm to 5 mm diameters of holes, 0.25 % to 25 % perforation rates, 0.5 mm to 5 mm thickness of the perforated panels with back cavities in which there are or are not glass wool absorption materials. The results of these simulations are good agreements with the results of our measurements by transfer function method except in the condition of more than 1 mm diameter of holes.

scholarly journals Lossy-Transmission-Line Analysis of Frequency Reconfigurable Rectangular-Ring Microstrip Antenna

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Bambang Setia Nugroho ◽  
Fitri Yuli Zulkifli ◽  
Eko Tjipto Rahardjo
Keyword(s):  
Transmission Line ◽  
Input Impedance ◽  
Microstrip Antenna ◽  
Reconfigurable Antenna ◽  
Resonant Frequencies ◽  
Rf Switches ◽  
Rectangular Patch ◽  
Full Wave ◽  
Lossy Transmission ◽  
Lossy Transmission Line

An analytical model for a frequency reconfigurable rectangular-ring microstrip antenna is proposed. The resonant frequencies and input impedance of the reconfigurable antenna are analyzed using a lossy-transmission-line (LTL) model. By making use of Y-admittance matrices, a formulation for the input impedance is analytically derived. The structure of the frequency reconfigurable antenna consists of a rectangular-ring shaped microstrip antenna which is loaded with a rectangular patch in the middle of the rectangular-ring antenna and fed by a microstrip line. RF switches are applied to connect the load to the antenna in order to reconfigure the operating frequencies. By modeling the antenna into a multiport equivalent circuit, the total input impedance is analytically derived to predict the resonant frequencies. To verify the analysis, the model input impedance and reflection coefficient calculation have been compared with the full-wave simulation and measurement results. The proposed model shows good agreement with full-wave simulated and measured results in the range of 1–3 GHz.

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