The volume of space, usually approximately conical with its vertex at the antenna, that cannot be scanned by an antenna because of limitations of the antenna radiation pattern and mount.
Note: An example of an antenna blind cone is that of an air route surveillance radar (ARSR). The horizontal radiation pattern of an ARSR antenna is very narrow. The vertical… (Read More →)

A device used to match the impedance of a transmitter and/or receiver to an antenna to provide maximum power transfer.

A power loss resulting from changes in the measurable impedance of a practical antenna from a value theoretically calculated for a perfect antenna.

The functionally equivalent area from which an antenna directed toward the source of the received signal gathers or absorbs the energy of an incident electromagnetic wave.
Note 1: Antenna effective area is usually expressed in square meters.
Note 2: In the case of parabolic and horn-parabolic antennas, the antenna effective area is about
0. 35 to
0. 55 of the… (Read More →)

The ratio of the total radiated power to the total input power.
Note: The total radiated power is the total input power less antenna dissipative losses.

The shaping of the radiation pattern in the vertical plane of a transmitting antenna by electrical means so that maximum radiation occurs at an angle below the horizontal plane. [47CFR]

The ratio of the power required at the input of a loss-free reference antenna to the power supplied to the input of the given antenna to produce, in a given direction, the same field strength at the same distance.
Note 1: Antenna gain is usually expressed in dB.
Note 2: Unless otherwise specified, the gain refers to the direction of… (Read More →)

In the characterization of antenna performance, a figure of merit, where G is the antenna gain in decibels at the receive frequency, and T is the equivalent noise temperature of the receiving system in kelvins.

The antenna height above the average terrain elevations from
3. 2 to 16 kilometers (2 to 10 miles) from the antenna for the eight directions spaced evenly for each 45° of azimuth starting with true north.
Note: In general, a different antenna height above average terrain will be determined in each direction from the antenna. The average of these eight… (Read More →)

A three-dimensional section of the radiation pattern of a directional antenna, bounded by one or more cones of nulls or by regions of diminished irradiance.