The Basic lessons · Feedlines and antenna systems · B-006-001

Connecting Your Radio to the Sky

This lesson explains how transmission lines carry radio energy from your transceiver to your antenna and what determines their electrical properties. You will learn why cable length does not change impedance and how to match your equipment to avoid signal loss.

This lesson is free to read; the rest are part of SignalPrep Pro. The subsection's 11 exam questions are free to practise: practise B-006-001.

What this subsection asks

• What connects your transceiver to your antenna?
• The characteristic impedance of a transmission line is determined by the:
• The characteristic impedance of a 20-metre piece of transmission line is 52 ohms. What would the impedance be if 10 metres were cut off?
• Why can coaxial cables of different diameters have the same characteristic impedance?
• What commonly available transmission line can be buried directly in the ground for some distance without adverse effects?
• A transmitter is delivering radio frequency (RF) energy into a coaxial cable with a characteristic impedance of 50 ohms. The cable is terminated by a purely resistive load. What value of load resistance will absorb all the RF energy it receives?
• What is the major factor influencing the velocity factor of a coaxial cable?
• The characteristic impedance of an open-wire transmission line depends, in part, on the diameter of its conductors. What other dimension determines its characteristic impedance?
• A transmission line is terminated by an impedance that differs significantly from the characteristic impedance of the line. What impedance will be measured at the input of the line?
• What factors determine the characteristic impedance of an open-wire transmission line?
• What factors determine the characteristic impedance of a coaxial transmission line?