TCI designs and produces a range of antenna systems to meet modern MF Broadcasting. TCI antennas cover the complete medium frequency band from 525 to 1605 kHz, with wavelengths from 571 to 187 meters respectively, and operate at carrier power levels from 1 kW to 2000 kW. TCI antennas are easy to install, require little maintenance, have a long life, and provide excellent broadcast performance.

Depending on the application, individual radiators may have heights as small as 0.1 wavelength or as large as 0.63 wavelength. Sophisticated TCI computer programs are used in the structural design of these large radiators to enable them to withstand varied and harsh environmental conditions and in the electrical design of antenna systems to produce prescribed patterns and impedance. This provides precise design parameters that assure the desired performance and reliability.

Types of MF Antennas Offered by TCI

MF antennas may be excited in a base-insulated, base-fed configuration or a base-grounded, shunt-fed configuration. TCI supplies both types, with the selection depending on the particular application. The base-fed configuration is the more conventional and has a better elevation plane pattern when used as an antifading antenna, which produces a greater interference-free nighttime coverage zone.

The base-grounded, shunt-fed configuration has the advantage over the base-fed configuration of not requiring a base insulator, a lighting transformer, or special lightning protection devices. In addition, the input impedance characteristics of the shunt-fed configuration often allow simpler matching units. One variation of the shunt-fed configuration is a folded monopole, with the shunt feed attached to the top of the mast. This design is useful in extremely high-power applications.

An earth mat or ground screen is provided with every antenna. The most common configuration employs 120 equispaced radials with lengths equal to the radiator height. Each antenna system is supplied complete with an appropriate matching unit to match the antenna impedance to that of the connecting unbalanced transmission line having a characteristics impedance in the range of 50 to 230 ohms.

For carrier powers of 50 kW and less, the matching units are supplied with weatherproof shelters; for high carrier power levels, they are usually mounted in walk-in type shelters. All matching units are appropriately interlocked for the protection of operating personnel.