VHF, UHF, and Microwave Repeaters: Extending Range

This article explains the function of repeaters used in VHF, UHF, and microwave frequency ranges. It also provides links to information about WiFi and LTE repeater types.

Line-of-sight communication, using direct waves, is characteristic of radio frequency signals above approximately 30 MHz. This is particularly true for VHF, UHF, and microwave frequencies. These signals pass through the ionosphere without bending, limiting their transmission distances considerably. Antenna height plays a crucial role in extending coverage. This is why FM and TV broadcasts often utilize very tall transmission antennas.

One way to increase transmission and reception range at high frequencies is to place the antenna on top of tall buildings or mountains. Another effective solution is to use a repeater station between the transmitter and receiver.

VHF/UHF Repeaters

The figure above (Figure 1) depicts a single repeater used to extend the range of VHF/UHF communication. A repeater consists of a receiver, a transmitter, and an antenna. Let’s break down how it works:

• The repeater receives the signal from a transmitter.
• It amplifies the received signal.
• Finally, it retransmits the signal on a different frequency to the receiver.

Microwave Repeaters

Figure 2 illustrates a series of repeaters used to extend the range of microwave communication. A classic example of this is the microwave relay stations used by telephone companies for long-distance communication. Each repeater in the chain performs the same functions as described above.

A string of repeater stations can relay signals across large distances. Typically, these relay stations are located 20 to 60 miles apart and positioned at high altitudes to ensure reliable communication over long distances.

Different Types of Repeaters

Repeaters are developed using various technologies and for different frequency bands. For instance, a repeater developed for WLAN networks is known as a WiFi repeater, while one developed for LTE networks is called an LTE repeater.