Vertical plane is used in radio to plot an antenna's relative field strength perpendicular to the ground (which directly affects a station's coverage area) on a polar graph.
Normally the maximum of 1.000 or 0 dB is at the side (unless there is beam tilt), which is labeled 0°, to 90° at the top and −90° at the bottom. Other field strengths are expressed as a decimal less than 1.000, a percentage less than 100%, or decibels less than 0 dB.
Most broadcast antennas use either line-of-sight or ground wave propagation (a slight refraction towards the ground) to reach their nearby listeners, and thus want a low angle in the vertical plane. Short wave transmitters want a somewhat higher elevation angle in the vertical plane to encourage skywave propagation, which would refract or reflect radio waves off the ionosphere and back to the ground at a great distance from the transmitter.
Omni directional antennas typically try to limit the range of their vertical plane radiation pattern to concentrate energy over a smaller range and increase gain.
Famous quotes containing the words vertical and/or plane:
“I tell you, hopeless grief is passionless;
That only men incredulous of despair,
Half-taught in anguish, through the midnight air
Beat upward to God’s throne in loud access
Of shrieking and reproach. Full desertness,
In souls as countries, lieth silent-bare
Under the blanching, vertical eye-glare
Of the absolute Heavens.”
—Elizabeth Barrett Browning (1806–1861)
“Have you ever been up in your plane at night, alone, somewhere, 20,000 feet above the ocean?... Did you ever hear music up there?... It’s the music a man’s spirit sings to his heart, when the earth’s far away and there isn’t any more fear. It’s the high, fine, beautiful sound of an earth-bound creature who grew wings and flew up high and looked straight into the face of the future. And caught, just for an instant, the unbelievable vision of a free man in a free world.”
—Dalton Trumbo (1905–1976)