Why Is The Height Of A VHF Radio Antenna Important?

The height of a VHF (very high frequency) radio antenna is important… The VHF radio should be… if a large antenna with a lot of capacity… calculating the correct height…

There is nothing more relaxing than a boat trip, motorboat or boat on a summer day, especially when there is a summer sun that appeases all annoying cold, warning that it is time to go out and have fun, but, you should not forget the safety of the measures that should accompany a fun boat or boat ride.

The VHF radio should be on the list of gadgets to take for a day out, as this will ensure that family members or friends are completely calm. Not only the VHF radio is important, but also the reception of calls or alerts from these radios is essential, then, what good is an excellent radio if the support and aid station does not receive the signals?

Radio receiving antennas are devices that must be in ideal conditions in terms of temperature, position, direction, height, and among other variables that can affect their reception performance, but one of the most important is height.

How does the height of a radio antenna influence it?

To understand the importance of a proper height, it is necessary to understand how electromagnetic waves travel in an environment. It is important to remember that VHF radio waves are low-frequency waves, which have a longer wavelength than very high-frequency waves, such as UHF. As VHF waves are low frequency, they travel a much greater distance than high-frequency waves, in addition to traveling in a straight line to another receiver, which implies that the obstruction of objects in the path affects the performance of the signal.

It depends on the frequency of the waves, it is that the propagation of Radio frequency (RF) signals behave because the waves react differently in various types of environments. The ionosphere, a layer included in the Earth’s atmosphere, is a layer that is divided into several sub-layers in which electric fields act in different proportions.

The innermost layer of the ionosphere is layer D, where the electric fields do not have the same intensity as in the outermost layers, which attenuates the path of the waves, so the height of the antennas would be beneficial both for objects that interfere with the transmission path and weak ionization fields.

How does the height of a radio antenna influence — Photo: quora.com

An important detail when considering a good height for the transmitting and receiving antenna is that the more excessively high the antenna, the ionization will interfere, so the height calculation must be accurate.

Calculating the precise height of a VHF radio antenna

The first value to be taken when calculating the height is precisely the height of the previously selected antenna. The height of the device itself will depend on the purposes it has, such as, for example, if it is a telephone signal in mountainous terrain, perhaps the antennas to be installed must be much higher than in flat areas. The height of the antenna can be in feet or meters, depending on this the formula will be applied. Having the height of the antenna, the following steps must be followed:

If we have the measurement of the antenna height in meters, we can convert it to feet, using the fact that 1 meter equals 3.2808 feet. Let’s start with the example in which we have a 10-meter antenna, and we would like to know how far it can emit the radio signal.

We multiply the height of the antenna in feet and multiply it by 2, then we calculate the square root of this product: When obtaining this number, we multiply by the number 1.33, which represents a factor of the roundness of the earth, since the waves follow this curvature slightly the greater the distance they travel, therefore:

8.1003×1.33 =10.7734

This result indicates that an antenna with a height of 10 meters can have a range of approximately 10.77 miles, which, converting to meters, approximately the range would be about 18 kilometers. This implies that, for greater efficiency in signal propagation, it is recommended to place antennas at a distance of just under 18 kilometers.

It should be noted that there are factors that can affect the performance of radio frequency emissions, such as the weather. Events such as electrical storms, cloud cover and irregularities in the terrain can affect radio emissions, but ways are always being sought to reduce the effects, such as the power of the transmitting antennas, the most strategic locations of the set of transmitters and receivers, and among other methods.

The importance of calculating the correct height

Failure to calculate the correct transmitting or receiving antenna height can lead to serious budget and performance issues. It should be borne in mind that, being a highly-populated area, with buildings of many sizes, many companies choose to rent or buy spaces on the roofs of buildings that are above the average height, in order to avoid the refraction of waves in buildings. Failure to determine the correct building for the antenna installation can cause infrastructure damage and even loss of complete antenna equipment.

Another important factor when calculating the height of an antenna is the signal strength generated by a certain organization or company that wants to use the waves to transmit a signal. If the signal transmitter does not have adequate equipment for a certain size of antennas, then if a large antenna with a lot of capacity is installed in a central that does not emit a good signal, then a very weak signal will be generated, which will cause a service very poor.

Conclusion

There are many other variables that the height of a radio frequency antenna can influence, but the most important thing to consider in order to avoid widespread problems is that equipment is used that meets current needs. It is not the same signal equipment from a station, mobile phone signals, or repeater signals for satellite internet, so it is imperative to detect the capacity required and the budget available, in addition to demographic factors. such as the terrain, as well as the weather stations.

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