How does antenna height influence of sea clutter?
Increased antenna height extends the radial limit of the overall sea clutter pattern which appears on the screen and also the range within which the clutter echoes saturate the receiver or the display.
How can antenna height be reduced?
1. Reduction in the height of antenna. For the transmission of radio signals, the antenna height must be multiple of λ/4 ,where λ is the wavelength . Thus, modulation reduces the height of the antenna .
What is practicality of antenna height?
Practical Length of Antenna: For the effective transmission of a signal, the height h of the antenna should be comparable to the wavelength λ of the signal at least the height of the antenna h should be λ / 4 in length so that the antenna can sense the variations of the signal properly.
How are radiation losses related to antenna 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.
How does the height of an antenna affect reception?
This has two effects. One is that as a receiver connected to the antenna is further away from any sources of interference on or near the ground. The second is that the transmitted signal from the antenna will be further away from anywhere that interference from the transmitted signal may cause an issue.
How much power does a 7MHz dipole antenna lose?
At these heights relative to a wavelength, the ground losses are most likely to be the dominant factor. It has been calculated that a 7MHz horizontal dipole antenna at a height of around 5 metres will only be around 50% efficient – half the available power will be lost as ground losses.
How much gain does doubling the height of an antenna give?
As a rough rule of thumb it is often said that doubling the height of an antenna will give a 6 dB increase in gain. Although this will depend upon the actual situation and a host of caveats, etc, studies have shown that it is generally not too far from the truth.