VHF Marine Band Radio Antenna Recommendation

VHF Marine Band radios, protocol, radio communication theory, practical advice; AIS; DSC; MMSI; EPIRB.
Spc337
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VHF Marine Band Radio Antenna Recommendation

Postby Spc337 » Wed Oct 07, 2020 11:40 am

[Separated from another discussion on an entirely different topic. Please do not join a discussion and then change the topic to an entirely different topic.--Moderator]

I’ve bought [a new VHF Marine Band radio with integral AIS receivers], and now I need antenna recommendations.

I’m in Puget Sound--a high traffic area--and I won’t travel offshore. I’ll be mounting the antenna on the starboard gunwale replacing an old 8-footer.

[Give me some] thoughts [about an antenna for VHF Marine Band for a boat whose size is never mentioned but can be inferred to be 22-feet long from the information in the signature of this post; when seeking advice about a VHF Marine Band antenna, be sure to mention the size of theboat].
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Phil T
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Re: VHF Marine Band Radio Antenna Recommendation

Postby Phil T » Wed Oct 07, 2020 1:09 pm

Get a 4-foot or 5-foot whip antenna on a 4-foot mast extension that is attached to a ratchet mount on the gunwale.
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Spc337
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Re: VHF Marine Band Radio Antenna Recommendation

Postby Spc337 » Wed Oct 07, 2020 2:23 pm

[Is there a] particular brand or model [of antenna that is recommended]?

I’m guessing the extension is to get height for [better] performance[. Is that right]?
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Re: VHF Marine Band Radio Antenna Recommendation

Postby Phil T » Wed Oct 07, 2020 2:39 pm

Jim has had good experience with GAM antennas.

As for the extension mast prices are silly. Go with an 8-foot antenna.

https://www.boatersland.com/sha5101.html

Same price on Amazon.

Little higher on Wholesale Marine:

https://www.wholesalemarine.com/shakespeare-classic-vhf-antenna/
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Spc337
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Re: VHF Marine Band Radio Antenna Recommendation

Postby Spc337 » Wed Oct 07, 2020 3:41 pm

Got it: skip the extension [mast] and 4-foot antenna and stick with the 8-foot antenna.

I’m assuming for inshore, a 3-dB or 6-dB gain antenna is the right choice[. Am I correct]?

I’m assuming these will pick up AIS signals.
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Re: VHF Marine Band Radio Antenna Recommendation

Postby jimh » Thu Oct 08, 2020 8:09 am

For installation on a smaller outboard boat, say something less than 30-feet long, I recommend an installation as described in my article in the REFERENCE section at

VHF Marine Band Antennas For Small Boats
http://continuouswave.com/whaler/refere ... tenna.html

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Re: VHF Marine Band Radio Antenna Recommendation

Postby jimh » Thu Oct 08, 2020 8:12 am

Spc337 wrote:[Makes a deduction that the best installation method is to] skip the extension [mast] and 4-foot antenna and stick with the 8-foot antenna.

Many people use 8-foot long fiberglass encapsulated pole antennas. The fundamental problem with these antennas is the fragility of the fiberglass. They don't last very long if there is any physical contact between the fiberglass pole and something sturdier.

Some 8-foot antennas contain only 3-feet-long radiating elements. The rest of the pole is just used to raise the antenna higher.

Spc337 wrote:I’m assuming for inshore, a 3-dB or 6-dB gain antenna is the right choice[. Am I correct]?

Antenna gain is of little importance, and on smaller boats antenna gain is a detrimental factor. All antenna gain occurs by narrowing of the radiation pattern. On small boats there is a lot of motion, so an antenna swaying around with a narrow radiation pattern is undesirable.

Spc337 wrote:I’m guessing the extension is to get height for [better] performance[. Is that right]?


Your guess is correct. Increased antenna mounting height is more important than gain. On a small boat there will be a lot of boat motion, and a so-called 3-dB gain antenna mounted as high as possible will produce the best results in preference to a higher gain antenna installed at a lower mounting base height. In general, doubling the antenna height is more effective than doubling the antenna gain.

Spc337 wrote:I’m assuming these will pick up AIS signals.

Antennas intercept all electromagnetic radiation that hits them. There is no possible method to design an antenna that only receives FM Voice signals sent in the VHF Marine Band and does not receive Frequency Shift Keyed AIS signals sent in the VHF Marine Band. Antennas convey the signals they intercept to a receiver. The receiver determines what frequency and what modulation methods can be received, not the antenna.

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Re: VHF Marine Band Radio Antenna Recommendation

Postby jimh » Thu Oct 08, 2020 8:24 am

Re the GAM SS-2 antenna and four-foot extension mast I described in my article mentioned above: after 12-years the GAM antenna failed. See my comments at

GAM SS-2 Antenna Fails after 12 years
viewtopic.php?f=13&t=4880

Also, due to a mistake on my part, the 4-foot extension mast failed in year 13 of service. See:

Shakespeare 468 Extension Mast Fails after 13 years
viewtopic.php?f=13&t=4880#p33309

I was able to get a repair part for the GAM SS-2 antenna, and I plan to re-use the antenna in the future. A further basis to prefer the GAM SS-2 is the method used to attach the whip to the base matching coil. There are several other very similar antennas made by other manufacturers, but the method used in those antennas to attach the whip is inferior to the method used in the GAM SS-2.

My most recently installed antenna is a MORAD VHF-156HD antenna which is mounted on a 2-foot extension mast. This project is described in a separate thread at

A Captivating Saga of VHF Antennas
viewtopic.php?f=13&t=5734

The MORAD antenna installation will cost about $300. The antenna is larger and heavier than many other marine antennas. It is best suited for larger boats, although on my 24-footer it looks appropriate. On a 17-footer I would not recommend it.

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Re: VHF Marine Band Radio Antenna Recommendation

Postby jimh » Thu Oct 08, 2020 9:01 am

Re antennas with exposed thin whip radiators: the whip is typically 36-inches long. The advantage of the whip is its durability. If the whip hits an overhead obstruction the whip will bend and survive. If a fiberglass pole antenna hits an overhead obstruction, the fiberglass pole is usually broken into two pieces, and repair is impossible.

Spc337
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Re: VHF Marine Band Radio Antenna Recommendation

Postby Spc337 » Fri Oct 09, 2020 3:12 am

Jim - lots of valuable information in those posts. I wish I had the time and knowledge to experiment as you have.

As I live near Seattle, I may investigate Morad.

Thanks for all the time and thoughtful insights you provide on the site!
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Re: VHF Marine Band Radio Antenna Recommendation

Postby jimh » Tue Oct 13, 2020 7:31 am

SPC--thanks for your kind comments. I have been interested in radio antennas for many decades. I have not really experimented with building any VHF Marine Band antennas of my own designs. I have just looked at various antennas available from manufacturers and tried several. I really liked the GAM SS-2 antenna and its ADAP-II mount for its light weight and modest cost, but at the moment there is not a reasonably priced 4-foot extension mast. Using a fiberglass-encased antenna in a 8-foot tube is probably the simplest approach, and if carefully handled the fiberglass antenna may have a long service life. The MORAD is a very rugged and well made antenna, and it should stand up to almost any abuse.

Spc337
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Re: VHF Marine Band Radio Antenna Recommendation

Postby Spc337 » Tue Oct 13, 2020 10:49 am

I went with the Morad. They are local. They make an antenna tuned between the VHF and AIS frequencies. Its length is 60-inches. They made a 3-foot extension that will fit on my existing base.

Should be more than capable for my needs.
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Re: VHF Marine Band Radio Antenna Recommendation

Postby jimh » Tue Oct 13, 2020 1:28 pm

My MORAD VHF-156HD antenna is installed with a 2-foot extension mast. It can be seen in my article at

http://continuouswave.com/forum/viewtopic.php?f=13&t=5734#p33818

Spc337
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Re: VHF Marine Band Radio Antenna Recommendation

Postby Spc337 » Tue Oct 13, 2020 5:24 pm

My antenna base mounting location is a bit lower on the starboard gunwale and [MORAD] recommended getting [the VHF-156HD antenna base mounted] above the boat’s steering wheel.
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