ABSTRACT
INTRODUCTION Transmission lines are one of the main components in the radiofrequency (RF) transmission plant of a broadcast station. Acting as the connecting link between the transmitter and the antenna, the transmission line plays a critical role in both the quality and reliability of the broadcast signal; therefore, the proper choice of a transmission line type to be used can have a significant impact on the success of the station. The choice of transmission line is typically decided based on the following criteria:
• Frequency of operation • Power handling capacity • Attenuation (or efficiency) • Characteristic impedance • Tower loading (size and weight)
With the implementation of additional digital broadcast channels, other criteria such as installation costs, connector design, reliability, and the effectiveness of transmitting multiple channels through the same transmission line are receiving renewed attention from design and broadcast engineers. There are a wide variety of transmission line types and designs to choose from. This chapter reviews the attributes of rigid coaxial and waveguide transmission lines to assist the broadcast engineer in the selection of the type best suited for a specific need.
