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Why Is the Height of a VHF Radio Antenna Important? – An Expert’s Explanation

Written by Anthony Roberts / Fact checked by Jonathan Larson

why is the height of a vhf radio antenna important

Antennas are used to correlate different VHF radios. As a result, appropriate antenna configuration is critical for clear interaction between users. In this regard, one of the most important factors is its height. Hence, if you are boater using VHF communication systems, you may wonder “Why is the height of a VHF radio antenna important?”

The height of VHF radio antenna systems is crucial because radio waves, like visible light, transmit in a straight line-of-sight. Obstacles such as trees will reduce clarity if it is too low. The taller the antenna, the wider the VHF frequency range is.

It is not easy for new boaters to acknowledge the importance of this radio component and figure out the way VHF transmissions function. Therefore, in this article, we have compiled a set of information about VHF signals, VHF range formulas, and other knowledge.

To help you understand VHF radio communication properly. Moreover, tips in operating VHF antennas and VHF’s antenna mounting techniques are also provided for boaters to practice installing VHF antennas more efficiently and effortlessly. Continue reading to learn more!

What Is VHF Radio?


1. An introduction to VHF antenna

The VHF antenna is an essential component of your radio system. The goal of this arrangement is to strengthen your communication skills, particularly around water bodies. These antennas’ purpose is to distribute the power from the broadcaster.

Every radio has a unit that controls the transmission of data through radio waves. This transfer results in the generation of electricity or energy. Nevertheless, the direction is uncontrollable – at least without a VHF antenna. The product directs power in the energy direction.

Moreover, antennas improve your communication skills by spreading this power to a location of your choice. As it is important to the basic operation of your network, the antenna’s length is crucial.

2. The definition of a VHF radio

It’s not exaggerated to say that the VHF radio is the heart of your boat’s protective equipment. VHF is an abbreviation for Very High Frequency, which relates to the radio spectrum of the signals emitted by these types of transmitters.

Because their higher wavelength signals may transit farther than UHF (ultra-high frequency) communications, they are mostly employed outdoors. Groundskeepers and security officers roaming outside an area may utilize VHF radios to communicate with each other. They’re also common on golf courses or in aviation and sailing.

In terms of a marine emergency, a VHF transmitter is your greatest option for contacting assistance. Even though VHF radios are not regulated by federal boating legislation, most manufacturers strongly urge boat owners to maintain one onboard, fully comprehend how to use it, and verify it is operational by putting it in a pre-launch assessment.

Furthermore, in non-emergency circumstances, VHF radios provide a handy and effective method of connecting with other sailors. Your VHF radio allows you to connect with your colleagues boat captains, alert a neighboring boat about possibly hazardous circumstances, comment on local villages onshore, or obtain information about a surrounding harbor.

How Does VHF Marine Radio Work?

An extremely high-frequency marine radio antenna operates by connecting to your network and channeling information through its design. It communicates with high frequencies.

Essentially, the term refers to waves that are extremely small in length. They attach to your preferred system and direct the radiant power in the right direction. These antennas come in a variety of shapes and sizes.

The kind you need is determined by how you want to utilize the system. For industrial or professional applications, the height of the antenna will often be around 70 feet to provide a longer range of frequencies.

The Importance of VHF Antenna’s Height


A VHF radio’s connection between two sites is based on high-frequency waves, which are parts of the electromagnetic spectrum that travel via the ionosphere. As a result, the ionosphere acts as a mirror, reflecting the VHF signal from above.

The data transmission distance that the antennas create is determined by the emission of a signal at a vertical position. A low-power direction, on the other hand, is required for long-distance communication. That’s why it is critical to set the antenna at the proper height.

Consider a VHF antenna to be a straight line of light. A building, a tree, or any other obstruction between two things obstructs light. It will not get to the opposite end, rendering it ineffective.

The same logic remains unchanged for the VHF frequency band. Since it is susceptible to impediments, if it is put on the floor, the signal can not approach the other end. The higher you place the antenna, the fewer obstructions.

However, this does not imply that you need to place the antenna excessively high. The antenna will be blown down by high-velocity winds. Assess the weather as well as the surroundings while determining the ideal antenna height for the best signal transmission.

The Calculation of Antenna Height

As previously indicated, VHF antenna heights have a direct impact on the radio’s range. Utilizing a VHF radio range calculator, we can determine the required height for certain range protections; several are available on the internet.

If you want to attempt determining the range individually, you may use the square root calculation below:

  • Range (miles) = 1.22 x square root of height

However, this method only computes the range of VHF broadcasts transmitting on a flat plane. In addition, statute miles are used in the derivation of this formula. For marine conditions, we’d rather use nautical miles, thus the calculation must be adjusted as:

  • Range (nautical miles) = square root of height

This is a much easier formula, however keep in mind that because one statute mile is approximately 1.15 nautical miles, this modification in the second calculation should allow us to approximate the increased range of among different communication channels in the radio system.

You should also notice that the height of the receiving antennas as well as its receiving ones is taken into account when calculating range. The VHF range formula for calculating the distance of two antennas is displayed as follows:

  • Range (nautical miles)= square root of transmitter’s height + square root of receiver’s height

How to Mount a VHF Antenna? – A Proper Tutorial

If you are practicing DIY VHF antenna installment, knowing the mounting technique is just as important as understanding how to calculate the height of the antenna.

There are several methods for attaching your VHF antenna. The selection on how to perform mounting is heavily influenced by where you intend to place the item.

First, decide where you would like to mount the antenna — aim for a location that is as high from the ground as feasible. Also, make sure the device that regulates the orientation of the radiation is far away from any metal.

Keep in mind that you must provide enough space to walk around the antenna. You must be able to navigate the correct direction.

The accumulation of EMF can have an influence on biological material over time. Therefore, give it as much space as possible. Assess the unit’s foundation. Maintain this as your principal point of comparison if your component requires a defected ground feature.

From here, you should proceed with caution while routing the cable. Even minor damage might have a long-term influence on the degree of atmospheric interference. To achieve the greatest results, ensure the wire’s course is straight and smooth.

Validate that the coax cable length stays at a suitable distance from the radio. At the very least, a meter is required. The greater the signal loss, the longer the line. Also check that you utilize the correct type of wire.

Then, deal with the interconnection itself. This is the location where the coax connects to the radio. Splice the cables together with caution. The more careful you are, the stronger your signal quality will be in the long term.

When every set up is done, conduct a quick test. Examine every part of the system. Analyze your range, transmission efficiency, and the receiving antenna.


Appropriate antenna height is crucial for best clarity in VHF radio transmission. The taller the antenna, the easier the frequencies may travel. Furthermore, it reduces potential obstacles hindering radio signals traveling from one radio to the other.

We hope that the above information will assist you and other boaters in installing and setting up a VHF antenna and VHF radio systems effectively, which makes your sailing journeys with family and friends safer!

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