How high does a VHF antenna need to be?

Marine VHF Antenna Height and Strength

A 3- to 4-foot antenna that's 3 dB is generally recommended for boats under 24 feet. Larger vessels can opt for 12- to 18-foot, 7 to 8 dB antennas. “As a general rule, antenna height should be less than half the length of the boat,” Catoe says.

Why is the height of VHF important?

The study, led by BHF Professor Sir Nilesh Samani at the University of Leicester, has shown that every 6 cm or 2.5 inch decrease in your height increases your relative risk of coronary heart disease by 13.5%.

Does a VHF antenna need to be vertical?

No matter how tempting it might be to angle your boat's VHF antenna for aesthetic purposes (like matching the angle of fishing rods), don't do it. Sure, it looks sleeker to have them angled, but they're designed to be positioned upright for a reason.

Does VHF antenna length matter?

The length of your antenna determines how good it is at handling certain frequencies; according to experts, there's a sweet spot that gives you the best signal. If you use an antenna that's too long or too short, your signal might cut in and out at times.

Where do you mount a VHF antenna?

For instance the VHF radios have highly magnetic components and can drastically deviate your compass. For best performance, mount your antenna at the highest point on your boat. T-tops make excellent places to mount antennas.

Antenna Height - why it is important, what are the benefits

How long should a VHF antenna be?

Marine VHF Antenna Height and Strength

Catoe says the vast majority of powerboats in the 24- to 32-foot range do well using 8-foot antennas with 6-decibel (dB) gain. A 3- to 4-foot antenna that's 3 dB is generally recommended for boats under 24 feet. Larger vessels can opt for 12- to 18-foot, 7 to 8 dB antennas.

How do I increase the gain on my VHF antenna?

Increasing the antenna height can also increase distance, so mount your antenna as high as possible, such as on top of your boat's hardtop or radar arch. You can also get greater range with a longer antenna — it has a larger radiating element.

How far will VHF transmit?

A typical VHF station operates at about 100,000 watts and has a coverage radius range of about 60 miles.

What is the optimal antenna length?

The most effective antenna has the same length as the length of the wave it is used for. For practical purposes, half or a quarter of that length will suffice. Most LoRa antennas are a 1/4 wavelength.

How can I improve my marine VHF reception?

Larger brass or silver plated internal elements on the antenna will be better performers and improve the transmission and reception of your signal. Notice the type of coax used with your antenna. All coax cable will increase incremental loss to your VHF system.

What is the minimum clearance distance you should maintain from antennas?

Maintain minimum 3 feet clearance from all antennas. Do not stop in front of antennas.

Does a ground plane antenna need to be grounded?

Knowing how to ground an antenna properly can make significant improvements to its performance, whereas a poor ground or earth connection can mean that its performance is greatly impaired. Grounding an antenna properly makes the antenna safe to use and also enables the best to be made of the performance of the antenna.

Why do antennas need to be grounded?

Grounding will eliminate static electricity, as well as protect against energy to the mast if the antenna comes in contact with live electrical wires. Outdoor masts should be grounded with Grounding Conductors (see F in diagram) to the building's Power Service Grounding Electrode System (see E) at a permitted location.

How far apart do VHF antennas need to be?

NMEA recommends 6 feet of vertical and horizontal separation between the VHF and AIS antennas. Most manufacturers recommend more.

How do you calculate antenna length?

Why does antenna length matter?

It all depends on what your transmitting and receiving frequencies are. Theoretically, a longer antenna will have a greater range, but it is far more important for optimal radio performance that the length of the antenna matches the frequency.

Does VHF work on land?

Do marine radios work on land? Marine radios can function on land; however, because marine radios are used by vessels in situations of distress, navigational issues, personal communication, and business needs, it is not legal for a person to use a marine radio on land without an approved coast station license.

What travels farther VHF or UHF?

VHF radio signals are on the low end of the frequency scale when compared to UHF. Although, VHF signal wavelength is longer, allowing it to travel farther than UHF.

What affects VHF range?

The key considerations that affect range are: signal type, antenna, obstructions, and signal strength (wattage). No single factor is a silver-bullet to extend your communication range. But taken in combination, they can mean the difference between getting 1/2 mile range, vs 6 miles or more.

Why is my antenna not picking up VHF?

If you're having trouble receiving one or two channels even though you're close to your local broadcast towers, it may be because your antenna is not designed to pick up VHF frequencies.

Do high gain antennas make a difference?

Since an antenna does not make power, increasing gain in one direction will decrease propagation in another. Typically, antennas with gain will lose the vertical propagation or “roundness” of the pattern and become flattened and elongated with the higher gain antenna you choose.

Why do some boats have 2 VHF antennas?

The advantages of the dual antenna

Not only does the installation of a second antenna give better readability to the AIS signal, but it can also serve as an emergency antenna for VHF. Just allow enough length behind the unit to disconnect the antenna from the AIS and connect it to the VHF.

What is the best VHF aerial?