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General-coverage receiver
A receiver used to listen to a wide range of frequencies. Most general-coverage receivers tune from frequencies below the standard-broadcast band to at least 30 MHz. These frequencies include the shortwave-broadcast bands and the amateur bands from 160 to 10 meters.

Giga
The metric prefix for 109, or times 1,000,000,000.

Grace period
The time FCC allows following the expiration of an amateur license to renew that license without having to retake an examination. Those who hold an expired license may not operate an amateur station until the license is reinstated.

Ground connection
A connection made to the earth for electrical safety. This connection can be made inside (to a metal cold-water pipe) or outside (to a ground rod).

Ground rod
A copper or copper-clad steel rod that is driven into the earth. A heavy copper wire from the ham shack connects all station equipment to the ground rod.

Ground-wave propagation
The method by which radio waves travel along the Earth's surface.

Half-wave dipole
A basic antenna used by radio amateurs. It consists of a length of wire or tubing, opened and fed at the center. The entire antenna is 1/2 wavelength long at the desired operating frequency.

Ham
An Amateur Radio operator licensed to operate amateur radio station.

Ham-bands-only receiver
A receiver designed to cover only the bands used by amateurs. Usually refers to the bands from 80 to 10 meters, sometimes including 160 meters.

Harmonics
Signals from a transmitter or oscillator occurring on whole-number multiples (2X, 3X, 4X, etc) of the desired operating frequency.

Health and Welfare traffic
Messages about the well being of individuals in a disaster area. Such messages must wait for Emergency and Priority traffic to clear, and results is advisories to those outside the disaster area awaiting news from family and friends.

Hertz (Hz)
An alternating-current frequency of one cycle per second. The basic unit of frequency.

High-pass filter
A filter designed to pass high-frequency signals, while blocking lower-frequency signals.