Study of Control of High Frequency over Voltage Standing Wave Ratio | Original Article

ABSTRACT:

ABSTRACT

After World War-II, the microwave engineering and technology have been developed a lot and opened several tremendous dimensions and scopes for the advancement in the field of Defence, microwave & Digital Communications, Satellite Communication, Computer & Information technologies. Microwave is an important component of Medical Science, Industrial and Defence growth of the country. For fast working of weapons, Defence needs Radar, Missiles and many other areas like Microwave Antenna, Microwave Ovens, Microwave Cellular Phones and Remote Sensing etc. All such activities are being pushed at a great speed. With the growth of Microwave Integrated Circuits (MICs) new technique has been developed with the emergence of computer science, engineering and technology with the recent advances in microwave communication system. High frequency signals can be sent to any corner of the universe. With the growth of digital communication our country moving very fast, new techniques are being designed where high frequency signal can be employed to control the propagation of waves through planar transmission line technology such as stripline, microstripline, coplanar waveguides and their variants. The most useful structure is micro stripline where metal strip conductor is separated from a ground plane by a layer of dielectric substrate. It is useful to convey high frequency signal of giga hertz range. It is also useful in high-speed digital printed circuit board designs. When two microstripline structures are placed parallel to each other in close proximity, a natural coupling exists between them forming a microstripline coupler. The characteristic impedance, propagation constant and coupling coefficients are the important characteristic parameters of this structure which are useful for the study of Directivity of the coupler, Reflection coefficient and Voltage Standing Wave Ratio (VSWR). The flow of energy in these two lines in the same direction constitutes even-mode and odd-mode when flow is in opposite direction. These parameters of the coupler are the functions of geometry of the structure and operating frequency. The incident and reflected parts of the waves form the Standing Waves having several maxima and minima. The ratio of maximum voltage to the minimum voltage constitutes the VSWR. The VSWR is related with characteristic impedance and reflection coefficients for even and odd-modes of wave propagation. These parameters of the coupler are the functions of geometry of the structure and frequency of the signal. The present paper aims at the study of VSWR and frequency control over it. The frequency of the signal plays significant role in the design of the directional coupler, Filters, resonators etc in the Giga Hertz range of frequency.