Dual band marine antenna

[Coquina]

I do OK using marine antennas for 2 meters, but I would love to find a 2 meter/440 marine antenna. Is there such a thing?

[Brian.D]

Well there is no 440MHz for Marine use, except EPIRB (406MHz). But there are tons of 2m/70cm antennas to be had. Pick one that is your favorite manufacture.

[Coquina]

Originally Posted by Brian.D

Well there is no 440MHz for Marine use, except EPIRB (406MHz). But there are tons of 2m/70cm antennas to be had. Pick one that is your favorite manufacture.

The point is none of them look suitable for a boat. Did you have one in mind?

[Captn_Black]

Antennas function by being a whole fraction of the wavelength they are designed to receive. So unless it is some super complicated hi-tech one that is effectively just two combined in a clever way, I doubt it.

i.e. 1/4, 1/16 wavelength etc

For example, SSB wavelength is 14meter, that is why 7meter whip antennas exist.

[S/V Illusion]

Originally Posted by Coquina

The point is none of them look suitable for a boat. Did you have one in mind?

Mobile antennas intended for vehicle mounting are equivalent without the “marine” label premium price. There are dozens from which to choose.

[Coquina]

Originally Posted by S/V Illusion

Mobile antennas intended for vehicle mounting are equivalent without the “marine” label premium price. There are dozens from which to choose.

No they aren't. Most of them are designed to be mounted on a flat metal surface that acts as a groundplane. If I thought a car antenna would work I would have bought one already

[S/V Illusion]

Originally Posted by Coquina

No they aren't. Most of them are designed to be mounted on a flat metal surface that acts as a groundplane. If I thought a car antenna would work I would have bought one already

Any antenna mounted on a mast, stanchion or pole inherently has a counterpoise (different than a ground) by its proximity to/ connection with the mount. Same thing - no difference.

[Coquina]

Originally Posted by S/V Illusion

Any antenna mounted on a mast, stanchion or pole inherently has a counterpoise (different than a ground) by its proximity to/ connection with the mount. Same thing - no difference.

It will be on a fiberglass mast - no metal.

[S/V Illusion]

Originally Posted by Coquina

It will be on a fiberglass mast - no metal.

No ground wire? No central aluminum core? We used to have a Freestanding mast Freedon 40 which had both. If it’s just a transom mount solid glass pole, a counterpoise wire is a no-brained solution.

[Coquina]

Originally Posted by S/V Illusion

No ground wire? No central aluminum core? We used to have a Freestanding mast Freedon 40 which had both. If it’s just a transom mount solid glass pole, a counterpoise wire is a no-brained solution.

It will be on an 8 foot fiberglass extension mast. I think I found something on FleaBay
https://www.ebay.com/itm/DBJ-1-Dual-...4383.l4275.c10


This is essentially narrow dual band J-Pole, no ground plane or radials needed. This may do the trick The base antennas commonly available, even if they did stand up to the motion and salt, have those radials at the bottom that would snag on everything and get bent or ripped off.

[Coquina]

Originally Posted by Captn_Black

Antennas function by being a whole fraction of the wavelength they are designed to receive. So unless it is some super complicated hi-tech one that is effectively just two combined in a clever way, I doubt it.

i.e. 1/4, 1/16 wavelength etc

For example, SSB wavelength is 14meter, that is why 7meter whip antennas exist.

Digressing a bit, but almost no one uses an untuned 1/4 wave HF antenna on a boat. My HF antenna works from 1.8 to 30 MHz. Absent a tuner, it would resonate on about 5.5 Mhz.

[Auspicious]

Lots of 2m/440 base station antennas are phased dipoles in a fiberglass radome and would do nicely. Ground planes are not a factor. I've had one--a Diamond X-50A--on my boat for 15 years. The antenna itself may be 25 years old. It was on my old house. It does have little counterpoise stubs.

[Dockhead]

Originally Posted by Auspicious

Lots of 2m/440 base station antennas are phased dipoles in a fiberglass radome and would do nicely. Ground planes are not a factor. I've had one--a Diamond X-50A--on my boat for 15 years. The antenna itself may be 25 years old. It was on my old house. It does have little counterpoise stubs.

I have that very antenna on my boat too.


It's not tuned for marine VHF (and that's not what I use it for) but it works ok. It's very good on amateur VHF/UHF bands.

[Captn_Black]

Originally Posted by Coquina

Digressing a bit, but almost no one uses an untuned 1/4 wave HF antenna on a boat. My HF antenna works from 1.8 to 30 MHz. Absent a tuner, it would resonate on about 5.5 Mhz.

I hate to be that "actually" guy, but I am planning to. There is a HF receiver only set-up I am going to install that uses a 1/4 or even 1/8 wavelength antenna, so that I can pick up satellite weather transmissions, and spend only $50 and 1 or 2 amps. Poverty is a great innovator.

The idea isn't mine originally, but I will make a post here and maybe a YT video when I do it. It uses freeware on the laptop, and a RF to USB convertor. And yes, I know how tuners work, thanks. I wasn't suggesting that he try use an antenna only.

Edit - You're right of course, hardly anyone uses it, because it is next to useless for transmitting, and commercial versions are non-existent as far as I can tell. But talking to people is over-rated :P

[Auspicious]

Originally Posted by Dockhead

I have that very antenna on my boat too.

It's not tuned for marine VHF (and that's not what I use it for) but it works ok. It's very good on amateur VHF/UHF bands.

I didn't realize you were a ham. I have a Kenwood TM-732A 2m/70cm. I listen more than I talk but I do a little APRS.

73 es sail fast de dave KO4MI

Originally Posted by Captn_Black

I hate to be that "actually" guy, but I am planning to. There is a HF receiver only set-up I am going to install that uses a 1/4 or even 1/8 wavelength antenna, so that I can pick up satellite weather transmissions, and spend only $50 and 1 or 2 amps.

WEFAX is a terrestrial service, not satellite. See https://www.weather.gov/media/marine/rfax.pdf . The products are excellent. I carry a small radio and wire antenna on delivery. Wavelength is really not relevant - you want as much wire up as high and clear as you can.

There is a satellite imagery service at 137 MHz. Most people use quadrafilar helix (QFH) antennas for that. The images are not terribly useful in isolation.

You may find the SDR dongles ("RF - USB converter") disappointing. The radio performance (sensitivity and selectivity) is mediocre at best. I really wanted it to work but went back to a portable SSB radio. There is a detailed thread elsewhere here on Cruisers Forum.