TC 9-64 — Communications-electronics Fundamentals: Wave Propagation, Transmission Lines, And Antennas
TC 9-64 governs Army communications-electronics fundamentals covering wave propagation, transmission lines, and antennas.
- Publication number: TC 9-64
- Title: COMMUNICATIONS-ELECTRONICS FUNDAMENTALS: WAVE PROPAGATION, TRANSMISSION LINES, AND ANTENNAS
- Date: 07/15/2004
- Proponent: T2COM
- Status: ACTIVE
View TC 9-64 on armypubs.army.mil
TC 9-64 explains sound, light, electromagnetic, and radio wave behavior, including ionospheric propagation and interference. It describes transmission-line terminations, standing waves, antenna types, radiation patterns, reciprocity, and antenna loading.
Topics covered
- Wave propagation
- Radio wave propagation
- Electromagnetic fields
- Transmission lines
- Standing waves
- Radio frequency safety precautions
- Antenna radiation
- Antenna characteristics
Questions and answers
How far is the radio horizon compared with the natural horizon?
Radio horizon is one-third farther than the natural horizon. (paragraph 5)
What happens when radio waves are transmitted above a layer's critical frequency?
Radio waves transmitted at frequencies higher than the critical frequency of a given layer will pass through the layer and be lost in space; but if these same waves enter an upper layer with a higher critical frequency, they will be refracted back to Earth. (paragraph 2-67)
What is the difference between a surface wave and a space wave?
Ground waves are composed of two separate component waves: the surface wave and the space wave. Surface waves travel along the contour of the earth by diffraction. Space waves can travel through the air directly to the receiving antenna or can be reflected from the surface of the earth. (paragraph 4)
What happens when a transmission line is not terminated in its characteristic impedance?
Whenever the termination on a transmission line is not equal to Z0, there are reflections on the line. (paragraph 1-6)
What does a 1:1 standing-wave ratio indicate?
A ratio of 1:1 describes a line terminated in its characteristic impedance. (paragraph 1-6)