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How does antenna height affect range?
A beam type of antenna at a height of 70 feet or more will provide greatly superior performance over the same antenna at 35 feet, all other factors being equal. A height of 120 feet or even higher will provide even more advantages for long-distance communications.
Why is the height of a VHF radio antenna important?
When considering marine VHF radio communications, more important than all other factors is the height of your antenna. The higher you can place your VHF antenna the further you will be able to communicate. Any angle beyond vertical will lessen the performance of your radio signal.
How does the height of the FM antenna affect its transmission?
As a result of these radio-wave characteristics, FM relies on line-of-sight transmission for station coverage. The result of lowering the receiving antenna to a few feet above ground is a loss of around 6 or 7dB, some of which is caused by soil effect. In AM operation, the signal is vertically polarized (Vpol).
Do VHF radios work by line-of-sight?
VHF radio waves propagate mainly by line-of-sight, so they are blocked by hills and mountains, although due to refraction they can travel somewhat beyond the visual horizon out to about 160 km (100 miles).
How does antenna height affect VHF communications range?
Of course terrain and surrounding buildings and landscape can greatly affect this number. You’ll notice that doubling the antenna height doesn’t automatically double the range. If you wanted to double the range, you’ll need to triple the height.
How tall does an antenna have to be to be effective?
angle, meaning that an antenna must be placed high above the ground in terms of the wavelength of the radio wave being transmitted. A beam type of antenna at a height of 70 feet or more will provide greatly superior performance over the same antenna at 35 feet, all other factors being equal. A height of 120 feet
What’s the theoretical range of a 30 foot antenna?
An antenna mounted at 30 feet should have a theoretical range of 7.78 miles. Of course terrain and surrounding buildings and landscape can greatly affect this number. You’ll notice that doubling the antenna height doesn’t automatically double the range. If you wanted to double the range, you’ll need to triple the height.
Radiation losses: It is found that if a horizontal antenna gets closer to the ground, then the losses due to the ground itself become more important and, at very low heights, they can be the main factor determining antenna performance. For example for a signal at 2 MHz, the wavelength is around 150 metres.