M&MA

Content Management System   Content Management System

Applications of Microwave Engineering The majority of today’s applications of RF and microwave technology are to wireless networking and communications systems, wireless security systems, radar systems, environmental remote sensing, and medical systems.

STAR DELTA connection Diagram and Working principle Descriptions: A Dual starter connects the motor terminals directly to the power supply . Hence, the motor is subjected to the full voltage of the power supply . Consequently , high starting current flows through the motor . This type of starting is suitable for small motors below 5 hp (3.75 kW) . Reduced-voltage starters are employed with motors above 5 hp. Although Dual motor starters are available for motors less than 150kW on 400 V and for motors less than 1 MW on 6.6 kV . Supply reliability and reserve power generation dictates the use of reduced voltage or not to reduce the starting current of an induction motor the voltage across the motor need to be reduced. This can be done by 1. Autotransformer starter , 2. Star-delta starter or 3. Resistor starter . Now-a-days VVVF drive used extensively for speed control serves this purpose also.

Comparison Between Transmission line and Wave guide : Transmission line Wave guide Small cross-section transmission lines (like coaxial cables) can only transmit low power levels due to the relatively high fields concentrated at specific locations within the device Metal waveguides can transmit high power levels. The fields of the propagating wave are spread more uniformly over a larger cross-sectional area than the small cross-section transmission line. Large cross-section transmission lines can transmit high power levels. Large cross-section (low frequency) waveguides are impractical due to large size and high cost .

  Design and Implement of QPSK Modem Based on FPGA. Abstract   : This paper presents a method to designs QPSK modulator and demodulator of a spread spectrum system which use field programmable device.  The method uses the tool of Quartus Ⅱ of American Altera Co. The whole system is divided into several small models based on top-down design method, and using VHDL hardware description language to design each model.