What are the Limitations of VHF and UHF portable radio communications?

What are the Limitations if VHF/UHF handheld radios?

The popular use of low cost handheld radio transceivers for pit to car communications is hard to beat in terms of an affordable solution for amateur motorsport. Examples of popular Radios are available from Zartek, Baofeng, Yaesu, Pofung and Rugged Radios.

These transceiver devices which are readily available globally and locally are typically designed to operate on this part of the radio spectrum:

VHF: 136-174 MHz

UHF: 400 to 480 MHz

Transmitting power varies considerably between 500 mw to around 5 watt whilst actual output in operational conditions is frequently less than this, they are sufficient for use at most local motorsport venues.

Radio transmission requires a clear path between antennas known as radio line of sight (LoS). Line-of-sight is defined as the straight line distance, clear of any objects, between the antennas.

This will enable reasonably reliable performance at most South African race circuits where the terrain is relatively flat and the vegetation is devoid of high trees. Kyalami and Killarney pose some difficulty at those points on the circuit where LoS is not possible. Dezi is likely to also result in some dead spots.

So how to get around this problem? Well that isa completely different discussion and will inevitably require the use of additional radios or special types of transceivers which are called Repeaters.

Longer communications distance are possible at most off-road venues and the vehicles themselves facilitate the installation of taller and so called high gain antenna.