Antenna Technologies From Hertz dipole to large antennas

Antenna designers are usually constrained by a set of specifications including operating frequency bands, radioelectric performance (gain, radiation patterns, polarization) and space requirements. Added to these criteria are environmental constraints (vacuum in space, industrial operating environment, housing integration as close as possible to control electronics, etc.).

In most cases, the frequency plan is fixed as the result of lengthy negotiations. The choice of antenna is then guided by the beam width required for the application and the gain achieved [E 3 280] . However, omnidirectional coverage can be achieved by subdividing space into sectors, as in the case of cell phone base stations, where each antenna covers 90° or 120° of the plane in question.

At this stage of the design process, antenna technology can therefore be chosen according to the space available, expressed in terms of wavelengths.

So we're going to follow this logic and grow the dimensions in this article, reviewing the main characteristics from the elementary antenna to the large antennas.

However, in many applications, the antenna is simply an "extension" of the propagation medium (guide or transmission line) [E 1 170] . This last point should be borne in mind by the designer when choosing the appropriate technology for the application to be developed, if losses associated with transitions between the propagation medium and the antenna are to be minimized.

A glossary of terms is provided at the end of the article.

For further definitions, see [E 3 280] .