Searching for a quality VHF/AIS combo antenna, Shakespeare 6500-WB found

A high-quality combination VHF and AIS antenna was on Gizmo’s shopping list this summer, even though I knew that it’s challenging to do both really well. The USCG Navigation Center spectrum diagram above tells the story (as does their detailed U.S. VHF Channel list): The marine VHF audio channels cluster around 157 MHz while the two main AIS channels are up at 162 MHz. That’s why dedicated VHF and AIS antennas are optimized differently (though each will perform the other job OK).

So for years, I’ve been advocating separate VHF and AIS antennas for maximum performance. But I’ve come to realize that on many boats there are good reasons to use just one antenna — typically along with a quality active AIS/VHF splitter — and several manufacturers now build “broadband” VHF antennas designed to handle the frequency disparity.

Moreover, I was impressed with Doug Miller’s detailed advice on this subject, because he’s helped thousands of Milltech customers with their AIS installs and proven himself a knowledgable and honest counselor in the process. In fact, I highly encourage anyone looking for better AIS and/or VHF performance to read Doug’s essay carefully, especially because I will now jump to the combo antenna I purchased partially on his advice.

Actually, you’ll see that Milltech sells numerous AIS/VHF antennas, and sailors should particularly note the Vesper Marine masthead whip. Their claim that it “has less than 1.5:1 VSWR at 156 MHz all the way up to 162 MHz” is as good a spec as I could find among several antennas that claim broad VHF frequency performance. But while I do prefer a detachable coax cable like the Vesper’s, I also wanted to use a standard 1″-14 base with a fiberglass antenna that would look more balanced among the several others on Gizmo’s mast spreaders.

At any rate, I count myself lucky to have found the Shakespeare Phase III 6500-WB Broadband 4-footer above, since it’s only listed among Shakespeare commercial antennas and not seen at many recreational marine distributors. But, oddly enough, Walmart sells them and so does Amazon (although the product photo shows a cell phone!), and that $143 price is a bargain for Phase III premium quality (and an 8-year warranty). I’ve never owned an antenna that felt nearly so well built, and the 6500-WB also claims that top “156-162 MHz, VSWR < 1.5:1” broadband performance.

By contrast, check out the 6396-AIS-R Phase III, with a claimed VSWR of <1.5:1 at 162 MHz and a 5 MHZ bandwidth within 2:1 VSWR. Or the 6400-R Phase III VHF with <1.5:1 at 156.8 MHz (Channel 16) plus a 3 MHZ bandwidth within 2:1. Actually, they’d make a great pair if separate AIS and VHF antennas are the goal, especially because they come with the standard Phase III mounting system that makes it easy to install, remove, or replace antenna or cable. But they also cost over $200 apiece, well over from some sources.

Mounting my Phase III 6500 was more challenging, though it did come with the super-rugged base shown in my photo. That complete mount, however, clamps to a sturdy pipe (vertical or horizontal), or bolts to something like the side of a flybridge, and while Gizmo does have both, I was determined to use one of my custom antenna mast platforms.

All that’s needed to use the Shakespeare 6500-WB with a standard 1″-14 antenna base is a double female ferrule like the Shakespeare 4006. However, the mystery one I had in stock includes that unusually large hole, and I wish I could link to a source because it turned out to be a significant feature in this case. With needlenose pliers and finger tips I could control the coax cable connector enough to screw the antenna into both the ferrule and cable at the same time, no cable twisting required. In other words, this mount functions something like the regular Phase III mount, though it might not come apart so easily after months of exposure.

Note the super low loss LMR400 coax cable, which I found on Amazon but could have had custom made. Yes, it’s thick and thus hard to fish through narrow cable raceways, but remember Doug Miller’s wise observation: “In my experience, the most important factor is the VHF antenna connected to the AIS system. And when I say VHF antenna, I include the antenna itself, the cable, the connector and the location of the antenna.”

I’m not going to claim that Gizmo’s antennas are ideally located, but they do all work pretty well, inspection and maintenance access is good, and I like to think they look sharp together. The 3 to 4-footers left to right are a Digital Antenna VHF antenna that’s served well for years — sometimes also handling AIS via a Vesper splitter– then the new Shakespeare VHF/AIS and finally the Glomex Glomeasy FM that’s kept me nicely tuned in since 2017.

Meanwhile, Gizmo is usually online thanks to the stubby though excellent Wave WiFi Rogue Reach Dual Band high-power WiFi system or the powerful Cel-Fi Go+ booster with its masthead antenna. Altogether the collection signifies many valuable cruising safety and communications capabilities (and makes me feel very fortunate).

And the heart flag? It’s been flying all summer, first to honor the frontline workers dealing with Covid, but then also for all those working to relieve people suffering from hurricanes, fires, and racial injustice.

Finally, I’d also like to honor Andrew Golden of Rushton Gregory Communications. I think that most of us in the boating industry know our increased lack of importance in this turbulent world, but Andrew’s still working hard at providing high-quality public relations. Which is to say knowing the products and companies he represents really well, and connecting us to test gear, images, and/or the product managers who can answer further questions.

In this case, Andrew had driven up from Portland to deliver a sample Vesper Marine Cortex AIS/VHF/monitoring system the day after they were delivered from New Zealand (retail inventory went out sooner, which was the right way to go given the delays). And while he did go home with a few fresh lobsters he saw hauled up to recently made over Junior, I almost immediately got the Cortex working with the Shakespeare antenna and will share the mostly wonderful details soon.