Reference antenna

Lore & Background

Reference antennas are chosen for their mechanical and electrical simplicity, which makes building repeatable antennas easier and allows the use of accurate design formulae. Common types include horns, dipoles, monopoles, and biconicals. Their performance is typically measured in high-accuracy facilities such as an electromagnetic anechoic chamber or another antenna test range, and the results can be compared with those from a second facility to reveal the accuracy of that facility or to calibrate it.

In some cases, rather than physical measurement, theoretical methods are employed. The antenna may be simulated using electromagnetic simulation, or its properties derived from formulae based on electromagnetic theory. These methods are only useful if the materials and dimensions of the antenna can be characterized very well and the mathematics is known to be accurate.

During relative calibration, an antenna's phase center offset and phase center variations are computed with respect to the reference antenna, which is normally assigned zero PCV values. This biases the calibration by the phase advance or delay experienced by the reference antenna. In absolute calibration, the test antenna is moved via a robot so that a particular satellite is received at different angles by both antennas, cancelling the reference antenna's effects and leaving only the test antenna's PCO and PCV.

Reader's Guide

The significance of the reference antenna lies in its role as a stable, known standard for antenna metrology. By providing a repeatable benchmark, it enables the calibration of other antennas and measurement facilities. The International Telecommunication Union maintains a database of reference antenna radiation patterns, which are theoretical equivalents to physical reference antennas, further supporting standardization. The use of mechanically and electrically simple designs—such as horns, dipoles, monopoles, and biconicals—ensures that the reference antenna can be reliably reproduced and its performance accurately predicted or measured. Its legacy is seen in the widespread practice of using reference antennas as transfer standards, where a single antenna measured at a high-accuracy facility is then used to evaluate or calibrate a second test facility. This process underpins the accuracy of antenna measurements across many applications, from satellite communications to radar systems, by providing a consistent point of comparison.

Did You Know?

• During relative calibration, the reference antenna is normally assigned zero phase center variation values.
• Common reference antennas include horns, dipoles, monopoles, and biconicals.