Transmission Lines

A system of conductors used to convey electric power or signal between two or more points

• Channels

• Optical cables

• Transmission lines

• Waveguides

These conductors are uniformly spaced by insulators. They have low losses at low and medium frequencies and are economical to construct and maintained

• Coaxial cables

• Open-wire transmission lines

• Optical cables

• Waveguides

To prevent radiation losses and interference from external sources, the inner conductor of this transmission line is completely enclosed with a metal sheath or braid

• Coaxial cables

• Open-wire transmission line

• Optical cables

• Waveguides

The term “balance line” means that

• Both conductors carry currents that flow in opposite directors

• Conductors present equal capacitance to ground

• One conductor is connected to ground

• A and B above

The characteristic impedance of a transmission line is determined by:

• Its operating frequency

• Its length

• Its physical size and arrangement

• The signal applied at the input terminal

The distributed parameters of the transmission line are: the series resistance; the series inductance; the shunt capacitance and the shunt conductance. What parameter was determined due to dielectric losses?

• Series resistance

• Series inductance

• Shunt capacitance

• Shunt conductance

Shunt capacitance was determined due to:

• Conductors were closed to each other

• The length and diameter of the conductors

• Dielectric losses

• Flux linkage

Series resistance was determined due to:

• Conductors were closed to each other

• The length and diameter of the conductors

• Dielectric losses

• Flux linkages

At radio frequencies, a line is considered lossless because:

• Characteristic impedance is determined by its physical structure

• Inductive reactance is much more than the resistance

• Capacitive reactance is much larger then the shunt conductance

• B and C above

10. Determine the characteristic impedance of a transmission line which has a capacitance of 30pF/m and an inductance of 75nH/m

• a. 5 Ω

• b. 50 Ω

• c. 500 Ω

• d. 5 KΩ