Best VHF Marine Band Radio Antenna

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

Postby padrefigure » Wed Mar 15, 2023 5:47 pm

Give me recommendations for the "best" marine VHF antenna. I am adding a T-Top to my 2004 Dauntless 22 and will be moving the antenna to the T-top. Based on this information, can the MORAD VHF-156HD antenna be considered the "best" antenna for small boat VHF?

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Phil T
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Re: VHF Marine Band Radio Antenna Recommendation

Postby Phil T » Wed Mar 15, 2023 7:26 pm

Not sure what makes [the MORAD VHF-156HD antenna the] "best". Maybe it's price.

Compare the Morad 6 dB gain at $266

https://www.morad.com/products/vhf-antenna-156-hot-rod

versus

Shakespeare 8-foot 6 dB gain antenna. Even at West Marine it's overpriced at $89.99

https://www.westmarine.com/shakespeare-mariner-8300-8--6db-vhf-antenna-6966048.html
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jimh
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Re: Best VHF Marine Band Radio Antenna

Postby jimh » Thu Mar 16, 2023 11:48 am

My recommendation for an VHF Marine Band antenna for a small boat typically is to use smaller antennas with length of three to four feet. These shorter antennas generally have a broader vertical plane radiation pattern so the movement of the boat will not cause much change in the signal. Longer antennas with higher gain will have narrow patterns in the vertical plane; boat movement will tend to cause more change in the radiated signal with antennas with more gain.

An antenna I used for many years with great success is the GAM ELECTRONICS SS-2 antenna. This is a metal whip antenna with a matching unit at the base. There are many similar antennas from other manufacturers, but my preference for the GAM SS2 is related to using it with a four-foot extension mast, which is aided by the antenna’s light weight and low wind area.

The use of a four-foot extension mast increases the height of the radiating element of the antenna. When starting from low height, raising an antenna produces improvement in signal at a very fast rate, more or less double the signal when double the height.

I installed a GAM SS-2 antenna on my own small boat. The antenna worked very well for over 12-years, until the base matching coil failed. I was able to replace just the base matching coil, rather than replace the entire antenna. See

GAM SS-2 Antenna Fails after 12 years
https://continuouswave.com/forum/viewto ... =13&t=4880

Unfortunately, about a year later the plastic extension mast I was using (made by Shakespeare) was damaged when it lost the battle with a large tree branch while I was towing the boat on the highway with the antenna erected in operating position. See

Shakespeare 468 Extension Mast Fails after 13 years
https://continuouswave.com/forum/viewto ... 880#p33309

MORAD VHF-156 HD ANTENNA
Most recently I installed a MORAD VHF-156HD antenna. I described the process in (perhaps too) much detail at

A Captivating Saga of VHF Antennas
https://continuouswave.com/forum/viewto ... =13&t=5734

I have been using the MORAD VHF-156HD antenna for three seasons of boating. I have no complaints about the performance of the antenna, but I have found that the weight and wind area of the antenna and its two-foot extension mast are perhaps at the limit of the old ratchet mount I am using on the boat. (I have a better ratchet mount, but it remains uninstalled due to the reluctance of the old ratchet mount to allow itself to be removed from the hull laminate; I think 3M5200 might have been used as the sealant-adhesive.)

For the particular instance in this discussion, mounting an antenna on a T-top on a 22-foot boat, I would expect that the antenna could be mounted using a ratchet mount base and no extension mast. In that mounting the MORAD VHF-156HD would be a fine antenna. I would also give thought to using the GAM SS-2 with an extension mast, which would increase the height by about three to four feet. This would improve the radio coverage, but it might also create a nuisance with higher vertical draft, particularly if the boat is being used in an area where low bridges have to be passed under. You might get tired of having to tilt-over a taller antenna.

THE GAM SS-2 ANTENNA AND MOUNT
I have been endorsing the GAM SS-2 antenna and its associated ADAP-II mount for years, but I have just learned of a better solution: GAM is now selling an improved mounting system with the antenna and the transmission line in a bundle they call the

Mini Series Stainless Steel ADAP+Antenna Package
The package includes your choice of Mini Series Antenna
  • SS-2 w/cut chart
  • SS-2 Marine (156 MHz)
  • SS-2 AIS (162 MHz)
  • SS-2 SPLIT (159 MHz)
  • a stainless steel mounting adaptor to 1-inch threaded mount
  • RG-58C/U transmission line, 15-feet
In this package the antenna is pre-installed on the stainless steel mounting adaptor, and the transmission line is included.

The GAM Electronics antenna products were sold by their founder (Ed Russell) several years ago to Yankee Microwave. Yankee Microwave moved the production of the antennas to Maine. I believe at that time the design of the ADAP-II mount was changed. The older ADAP-II used a threaded mounting of the antenna into the adaptor; the new ADAP-II relied on a press-fit of the antenna into the adaptor. The fitment of the antenna into the adaptor became a problem for Yankee MIcrowave; The plastic press-fit ADAP-II mount relied on the knurling of the captivating collar of the attaching UHF-series cable-end plug (PL-259) connector for the necessary friction into adaptor body. Those connectors were increasingly becoming available only from vendors in China, and there were inconsistencies in the manufacturing of the knurling patterns. To overcome that, and at the same time improve the mount, they designed a stainless steel mounting adaptor. The stainless steel mounting adaptor is a better choice for marine use, and at a price of $141 (for the bundle) the cost is only slightly greater than the plastic mount option. The transmission line continues to be Mil-Spec RG-58C/U cable, which is very good quality. I recommend buying this bundled package, and for VHF Marine use with just a ship station VHF transmitter, ordering the SS-2 Marine version. The SS-2 AIS would be appropriate for dedicated use with an AIS transmitter, and the SS-2 SPLIT would be used if the antenna is to be time-shared with VHF ship station and AIS transmitters.

Regarding manufacturing in Maine, GAM tries to source all the materials and components they can from local suppliers, keeping the product as much Made-in-USA or Made-in-Maine as they can. They're a small company, not a giant operation.

ANTENNA GAIN
Regarding the citing of a figure of merit for the gain of VHF Marine Band antennas: these numbers are generally quite fanciful. Actual measurement of antenna gain is quite difficult. There seems to be a general overstatement of antenna gain among all manufacturers. There is an unusual correlation between length in feet and gain in decibels, which really makes little sense. These gain figures seem to be assuming use of the antenna over a perfect reflecting ground and are referenced to a theoretical isotropic radiator. I don't put much faith in the claimed antenna gain or worry much about it. A well made three-foot antenna can work extremely well compared to a poorly made 8-foot antenna.

METAL RADIATOR
You will note that I mention two antennas with exposed metal radiating elements. Neither of these antenna should be used in a situation where anyone could grab for the metal whip part of the antenna.

FIBERGLASS ENCASED ANTENNAS
If a fiberglass-encased antenna is desired, I would probably use a Shakespeare 6400-R which sells for just under $300. See details of its installation at

https://shakespeare-marine.com/wp-content/uploads/2023/01/6400-R.pdf

The transmission line is not included.

--or--

DIGITAL-brand 526-VW antenna which sells for about $175, also without transmission line. See

https://www.digitalantenna.com/pdfs/DA_ ... tennas.pdf

Digital says this series was "voted the best 4' VHF antenna by PowerBoat Reports," but that magazine ceased publication in 2007, so I am not sure if that is the most up-to-date source of reviews of current antenna products. Also, no link is ever given to the actual report.

CLASSIC OLDIE
Another antenna I would consider is the Shakespeare 396 model. This antenna has been production for decades without any changes and was often used by the USCG. See

https://shakespeare-marine.com/wp-conte ... /396-1.pdf

This oldie sells for under $150 and includes a permanently attached 15-foot transmission line using RG-58 cable.

ASIDE: I can't find any mention on the Shakespeare company website of a "Mariner" line or a model 8300. I wonder if those are private-label products for WEST Marine.

padrefigure
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Re: Best VHF Marine Band Radio Antenna

Postby padrefigure » Tue Mar 21, 2023 10:53 am

Thanks for the information. I ordered the SS-2 Marine and look forward to getting it installed.

Just one aside:

Have you noticed a sharp uptick in freight charges? I ordered the SS-2 Marine and the default freight selection was Priority Mail Express at $95.95. Ouch! The least expensive option was USPS Priority at $27.20 or over 20% of the cost of the goods being shipped. Even ground UPS was $34.26. I've noticed this with ebay and other online sellers as well. While margins may be squeezed at the manufacturer level, it appears that freight carriers have substantial pricing elasticity.

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Phil T
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Re: Best VHF Marine Band Radio Antenna

Postby Phil T » Tue Mar 21, 2023 5:18 pm

Padre - It could be "Shipping" or "Shipping (including "handling").

Freight charges have been under pressure due to higher costs. Diesel is still $1 to $3 a gallon more since whenever it went into stupid expensive territory.
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jimh
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Re: Best VHF Marine Band Radio Antenna

Postby jimh » Wed Mar 22, 2023 5:48 am

The big retailer DEFENDER usually has the GAM SS-2 antenna in stock.

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Re: Best VHF Marine Band Radio Antenna

Postby jimh » Thu Aug 24, 2023 7:48 am

I recently spoke with New England Microwave about a few aspects of the new GAM SS-2 ADAP+ bundle. Here's what I found:

  • the price has increased to $141 for the bundle;
  • the coaxial cable exits at the bottom, so the ratchet mount must be able to accommodate the cable routing through the mount; there is no side exit stainless steel mounting adaptor;
  • there are now options for black or white, which refers to the color of the outer jacket of the coaxial transmission line;
  • the SS-2 matching coil used with the new stainless steel mount adaptor does not have an SO-239-type receptacle; it uses a smaller diameter coaxial connector;
  • if necessary, the coaxial cable can be replaced in the field; the matching coil can be disconnected from the adaptor in the field; the metal whip can be disconnected from the matching coil in the field;
  • reports of very high shipping cost can be in error; see below;
  • in shipping their product, GAM Electronics does not coil the coaxial cable into a very small radius with tight bends; this is done to prevent damage to the cable from being bent excessively while boxed up and waiting to be sold.

The website ordering process on the GAM Electronics website estimates the shipping costs for various shipping methods based on an algorithm provided in a shipping "module" used in the on-line "cart" ordering system. Sometimes the estimates are much higher than will actually be necessary. If you are ordering from GAM via their website order process, and you get a crazily-high cost for shipping, just call GAM Electronics and speak to them. They can usually resolve the shipping costs to be more appropriate.