TV signal is almost always present. Signal is actually part of the light spectrum. Light you perceive it because it illuminates your environment but the RF spectrum is tucked away in that light. Man has learnt how to use it to transport messages around the globe. Like the trading barges of the past riding on the river the TV signal rides on the back of this natural wave/ energy called RF spectrum: Radio Frequency spectrum. An interesting thought why is it call Radio Frequency and why not something else.
Around 1800 one William Hersche noticed the temperature of the light spectrum did not stop at the colour of red the temperature continued to rise and many years later around 1870 James Clerk Maxwell the Scottish physicist predicted the existence of waves that could be used and were present in the light spectrum. Heinrich Hertz, a German physicist, applied Maxwell’s theories to the production and reception of radio waves and Nikola Tesla was the inventor of the radio in the late 19th Century.
So they have always been present in our environment but we learnt to manipulate them more and more to carry information from one place to another. So we needed a Transmitter, receiver (antenna) and processor (TV, Radio, 4g mobile phone, satellite dish) The TV, Phone etc., simply decodes the information that has been transported by the wave. So these waves are everywhere and if we could see them they would be different lengths and different strengths and they would be travelling horizontally or vertically depending upon the design of the of the transmitter.
This is very important because it tells you how to mount your antenna to pick them up. You can get this information on a smartphone as there are apps now available which will provide the information needed when travelling from place to place. For Android phones, there is Digital TV Antennas or DVB-T Australia. For iPhones there is Antenna Mate.
Even where the Transmitter is Horizontally polarized I have heard many conversations where someone says “my antenna worked and it was vertically mounted .” This can be true because the environment and particularly the weather can impact the wave and change its pattern. As it bounces off an oblique rock face, etc . A bit like the wind blowing will change the shape of the tree or the surface of a large body of water. It is temporary though, and in circumstances like this people will get their wrongly mounted antennas to work. In addition the higher frequencies (due to short wavelength) can still sometimes work if the signal is strong.
This tends to confuse people because they do not know what to believe. If we go to the source, the telecommunications ministry of Australia, we will discover that every transmitter on our continent is designated as either Horizontally or Vertically polarised. It is roughly half of each. Wilkgard Technology Group is a technical RF company. If we sell a product we want to know it is fit for purpose. We are driven by results however many of our peers and associates are driven by the mighty dollar. Caravanners need to take some responsibility too as many want a simple and convenient method and are drawn to impractical answers when the technical requirements are not understood.
This does not mean they will never work. They will work but so would almost any antenna if levels are good and interference is minimal. I think an antenna should be designed and built for the worst situation, not the best. The best is plenty of signal with no real enhancement from the antenna beyond picking it up and sending it down the cable. You hear of caravanners saying “I picked it up on my indoor so you do not need an antenna.” That is true for that location and position in that caravan park. Like real estate it is position and then it is position and position.
Testing is part of the game of looking for signals. I have done thousands of hours over the years and will give you some tips on setting up your antenna.
You need to know:
Many years ago I spent some time on Flinders Island researching how they could get reliable Television from Mt Barrow in the North of Tasmania not far from Launceston. The weather howled and the winds were regular visitors. The terrain was hilly with valley floors and rocky outcrops. The sea temperatures varied season to season and it was a significant distance to the transmitter.
But the terrain generally being granite with volcanic deposits is helpful. Signals persist in this type of environment as the environment itself keeps the signal moving and tends to amplifier it. Using the environment the antenna installation was kept quite low to the roof as the ground supported the electromagnetic nature of RF signals.
This is true for the caravanner. In this type of ground do not go hoisting your antenna as high as possible Keep it above the aluminium roof (50cm) but use the signal path to advantage. For example another time a perfect signal bounced of a vertical granite cutting landing right next to a chimney making the installation simple. This was in a Narbethong in Victoria. The signals came from Bendigo some 160 kilometers away.
Valley floors are perfect provided you are not knee deep in sand. Look at the direction of the signal and inspect what is in the way if anything. Pine trees are unique. They seem to be able to bar the signal from passing. You have to get over the top or under the foliage.
Moreover, you can use the aluminium roof of your caravan. This is a great space for signals to land. The roof, like granite (or anything with iron or in it – or the large flat aluminium side or roof of the van) is a source of using electromagnetic energy. This is needed if the signal is to flow through the air. Adjustments should not be more than 50mm at a time. Adjustments in vertical height and horizontal positioning to take advantage of the signal path. This is difficult in a caravan as you generally have one mounting position. If a caravanner is in the wilds I would recommend another mounting location.
Like one on the side and one on the front to take advantage of the angles for best reception using the environment to advantage. An antenna in a vertical position to receive a signal from a vertically polarised transmitter.
The hardest terrain is sand. it can completely wipe out the signal and allow it to transmit only over a relatively sort distance.
RF Consultant Founder
Wilkgard Technology Group P/L