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INTRODUCTION TO THE PRESENTATION • Two port network• Impedance matching• Transmission lines• Telephone systems• Loudspeakers

AIM OF THE PRESENTATION Explain two port network The applications of two port network in systems and devices

TWO PORT NETWORK The two port network is a device that contains pair of terminals, it

main job is to find characteristic parameters through isolating part of the circuit or the full circuit, in order to make the circuit of characteristic properties.

IMPEDANCE MATCHING Impedance matching is a process attempting to equalize the output

impedance of a source with input impedance of the load in order to make them eventually connected.

This process generally applies to boost the power transfer to the highest point, and decrease reflection from the load.

Impedance matching it a term used on two impedances that work harmonically, without the need to make two impedances complex conjugate. Bridging connections are applied in order to reach the highest voltage transfer, not the power transfer.

TRANSMISSION LINES Impedance bridging causes a power reflection on the source from

the limit of the high and low impedance, therefore it is not a convenient for the RF connections.

The reflection will eventually cause power waste due to the standing waves that is created in the operation.

Thus impedance matching is vital in these systems. Transmission lines plays a huge role in the electrical systems, because it prevents the reflections that could cause disturbances in the signal that could cause echoes in devices such as radio, by matching the impedances to the transmission line’s characteristic impedance.

TELEPHONE SYSTEMS Telephone system likewise use the matched impedances to reduce

the echoes as much as possible on the long distance. As well as to help the telephone hybrid coil (2 to 4 wire conversion)

to function appropriately. When the signal is send and received on the same two wire circuit

to the central office, cancellation is important and has to be implanted to the telephone earpiece to remove the excessive side tone. The impedance that is used in the telephone system’s loop is 600 ohms.

LOUDSPEAKERS The newest versions of audio amplifiers do not practice the matched

impedances, due to the driver amplifier does not provide enough output impedance, it has only about 1 ohm and the loudspeakers usually has input impedance of 4 to 16, many times bigger.

It uses the impedance bridging to deliver improved damping of the loudspeakers cone to reduce the distortion to limit.

END OF THE PRESENTATION • any questions? If so you could visit the below websites for a lot

more details http://fourier.eng.hmc.edu/e84/lectures/ch2/node4.html

http://www.powerelectricalblog.com/2007/03/two-port-networks-z-y-h-g-abcd.html

Two-Port Networks - University of Kentucky