scholarly journals Study of the Interference Affecting the Performance of the Theremin

2012 ◽  
Vol 2012 ◽  
pp. 1-9 ◽  
Author(s):  
Carmen Bachiller Martín ◽  
Jorge Sastre Martínez ◽  
Amelia Ricchiuti ◽  
Héctor Esteban González ◽  
Carlos Hernández Franco
Keyword(s):  
Electromagnetic Field ◽  
Antenna Array ◽  
Three Dimensional ◽  
Musical Instrument ◽  
Musical Instruments ◽  
Physical Contact ◽  
Short List ◽  
Full Wave ◽  
Ansoft Hfss ◽  
Field Simulation

The theremin is one of the earliest electronic musical instruments. It is named after the Russian physics Professor Lev S. Termen who invented it in 1919. This musical instrument belongs to a very short list of devices which are played without physical contact between the musician and the instrument. theremin players complain about the interference that any object in a radius of approximately 3 meters produces when playing the theremin, modifying the intonation of the instrument. This is a problem when playing in small scenarios, with other musicians which move around it. With the aim of reducing the degree of interference from nearby obstacles, some metallic isolating bars conforming an antenna array can be placed around the theremin pitch antenna. The paper shows different simulations calculated with the commercial software Ansoft HFSS, a tool which allows three-dimensional full wave electromagnetic field simulation, with radio frequencies, millimeter and micro waves, and experimental measures, both showing a reduction in the effect of the interference.

scholarly journals Simulation of electromagnetic field distribution in the measuring cell for determining the dielectric permittivity of materials at microwave frequencies

Doklady BGUIR ◽  
2020 ◽  
Vol 18 (6) ◽  
pp. 75-80
Author(s):  
N. A. Pevneva ◽  
A. A. Kopshai ◽  
A. L. Gurskii
Keyword(s):  
Electromagnetic Field ◽  
Dielectric Permittivity ◽  
Theoretical Calculations ◽  
Three Dimensional ◽  
Wide Frequency Range ◽  
Frequency Range ◽  
Polyethylene Tube ◽  
Dielectric Parameters ◽  
Measuring Cell ◽  
Ansoft Hfss

To determine the dielectric permittivity of materials in a wide frequency range with the automation of measurements and the necessary accuracy, measuring cells have been created to ensure the simplicity of the design of the waveguide path. In order to obtain information about the suitability of measuring cells based on irregular SHF waveguides for estimation of dielectric parameters of materials, we simulated the structure of electromagnetic field in the system consisting of two irregular waveguides and waveguide chamber placed between them using a three-dimensional electrodynamic simulation in Ansoft HFSS package environment. The distribution of the electric field was simulated when an empty polyethylene tube, a rod of fluoroplastic and a rod of textolite are placed in the measuring cell. It was demonstrated that high order modes fade out in irregular waveguide and do not affect the precision of obtained results, and significant edge effects were not detected. It allows one to utilize measuring cells based on irregular waveguides together with a scalar or vector network analyzer and using the partial filling of the waveguide method or the modified Nicholson – Ross – Weir method for measurements of dielectric permittivity  of materials. The results of modeling the dependence of the amplitude and phase of the reflection coefficient of the textolite and fluoroplastic on the frequency in Ansoft HFSS environment are given. The simulation results are compared with the results obtained experimentally. The frequency dependencies of  were obtained experimentally for test materials – textolite and fluoroplastic – in the frequency range of 25,95–37,50 GHz. The experimental data are in satisfactory agreement with the results of theoretical calculations and do not go beyond the boundaries specified by the measurement uncertainty.

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