Array. - is the form an assembly of radiation elements in an electrical and geometrical configuration. This antenna that contain multi-elements is referred as Array.

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There are two types of antenna ranges:

- The reflection ranges: are designed to create a constructive interference in the region as “quiet zone”, can be adjusting the transmitting antenna height, ranges are for outdoor type, the ground is the reflecting surface and usually employed in the UHF region.

- The free-space ranges: are designed to suppress the contributions from the surrounding environment. Include:

- Elevated ranges: These ranges are used to test physically large antennas.

- Slant Ranges: The source antenna to give the pattern maximum, and the first null is usually directed toward the ground specular reflection point to suppress reflected signals.

- Anechoic chambers: provide a controlled environment, all-weather capability, security, and minimize electromagnetic interference, indoor anechoic chambers. Test use chambers with RF absorbers.

- Compact ranges: required that the radiation under test be illuminated by a uniform plane wave. Are usually achieved only in the far-field region.

- Near-field ranges.

CATR Designs

Four reflector configurations that have been commercially developed will be briefly:

- The single paraboloid

- The dual parabolic-cylinder

- The dual shaped-reflector

- The single parabolic-cylinder systems

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Radiation Pattern: the pattern of antenna is three-dimensional. Because is impractical to mesure a three-dimensional pattern a number of two-dimensional patterns are measured.

A three dimensional graph is determinated by the functional requirements of the description, and the available time and funds. The minimum number of two-dimensional patterns is two.

Instruments:

- Source antenna and transmitting system

- Receiving system

- Positioning system

- Recording system

- Data-processing system

The performance of a radiator is the gain

Are two basic methods that can be used to measure the gain of an electromagnetic radiator:

- Absolute-gain

- Gain-Transfer

Gain Measurements. – is accomplished by multiplying the directivity by the efficiency to result in the gain.

The techniques to make absolute-gain measurements are based on the Friis Transmition which assumes that the measuring system employs, each time, two antennas.

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