Recently we went aerial spotting for communications aerials around Lincoln.
We cunningly disguised ourselves inside a number 15 bus, armed only with our eyes.
For those people who say that two way radio communications is a thing of the past, I have news for you.
There are many business radio antennas on chimneys and roofs, as well as on vehicles, proving that radio comms is alive and well.
Its not just two-way voice communications that is being transmitted, telemetry and the rapidly expanding Internet Of Things is resulting in an antenna increase.
Many of the latest vehicle antennas can be very discrete, so you have to keep you eyes peeled to spot them, and some re even deliberately designed not to be seen.
Probably the most common type you will see on a vehicle is the vertical dipole whip.
These ‘whip’ antennas (aerials) often are attached to a magnetic mount base, that can be easily attached to a metal vehicle roof.
This saves having to drill holes in the vehicle, which is less popular these days, as many business vehicles are now leased, rather than owned.
You may have noticed that the whip aerials on vehicles such as taxis, vary in length. This is due to resonant frequency.
For a transmitting antenna to work at maximum efficiency, it needs to be made for a specific resonant frequency.
Whip aerials on vehicles often come as a long length, which needs to be cut to the correct length.
Short Steel Whip Aerials (around 15cm long) are operating in the UHF frequency band, roughly around 450Mhz (Mega Hertz).
Medium length Whip Aerials (around 45 cm) are probably operating in the VHF wave band, roughly around 160Mhz.
Long length steel whip aerials (typically around 91cm long) are either operating in VHF ‘Low Band’, around 77Mhz, or have not been cut to the correct resonant frequency .
One our aerial spotting trip, we saw many examples of both the medium and long length (VHF) aerials on taxis around Lincoln.
A Yagi is a directional Aerial (Antenna) created by a Japanese inventor (hence the name).
This is probably the easiest and most common aerial that you will spot.
The Yagi aerial is most commonly used for television reception, and therefore most houses have one strapped to the chimney.
You may also have spotted Yagi antennas situated on land owned by water, gas and other utilities. These are used for sending and receiving telemetry.
The Yagi is a directional aerial, which makes it good at receiving and transmitting signals in one direction.
Therefore next time you spot a yagi, have a look at which way it is pointing. The way it is pointing will be the small end (away from the pole it is mounted on).
Other Types Of Aerial
There are quite a few other types of Aerial, such as Co-Linear, Microwave and Satellite Dishes, and we may extend this article to include them at a later time. Alternatively for advice, contact us.
Aerials (Antennas) are connected to the radio receiving and transmitting equipment by a special cable, abbreviated to Coax.
Coax is short for Coaxial Cable, and is available in a number of types, suitable for different radio operating frequencies and applications.
Careful selection of the correct cable is crucial to ensure that your transmitter / receiver works well.
The use of an incorrect type of coax, can actually risk damaging transmitting equipment, as not all the RF power will travel up to the aerial (some will be reflected, back down, etc)
For help with radio communications in normal persons language, why not give the Yesway team a ring!
(C) 2011-2018 Yesway Communications (Yesway Ltd)
Written by Craig Miles at Yesway Ltd https://www.linkedin.com/in/craig-miles/
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