What type of antenna is this?

[RBCurtis]

New (to me) boat, first time boat owner.

I have two of these antennae, one on each side of the solar arch.

Can anyone tell me what they are for? I have a VHF antenna on the mast, and a GPS antenna on the rail ...

Thanks!

[Jammer]

They are probably auxiliary VHF antennas for a second VHF radio or an AIS receiver or transceiver.

[RBCurtis]

Originally Posted by Jammer

They are probably auxiliary VHF antennas for a second VHF radio or an AIS receiver or transceiver.

Interesting ... only one VHF currently. But hard to say what equipment was on-board at some point previously.

No working display at the moment for AIS ... could be a receiver/transceiver somewhere. When I'm back on the boat next month I'll try to trace the cables.

Thanks!

[RBCurtis]

This is a GPS antenna, right?

[Zanshin]

Yes, that is a GPS puck

[SV_FlyingTigress]

Originally Posted by RBCurtis

Interesting ... only one VHF currently. But hard to When I'm back on the boat next month I'll try to trace the cables.

^ This ^

[Brian.D]

Looks too small for VHF. Small meaning the element is short. I might guess it is something in the UHF range. Maybe the PO was a ham and used UHF.

JMHO

[NYSail]

No access to previous owner? Maybe a WiFi booster??

[Zanshin]

The antenna in the first image is the same size as my AIS VHF antenna.

[RBCurtis]

Originally Posted by NYSail

No access to previous owner? Maybe a WiFi booster??

The previous owner has been helpful, but he bought the boat sight unseen just before Covid and then it sat for two years before he sold it. So he never really had an opportunity to know all the systems.

[RBCurtis]

It’s just odd. In addition to the two identical and unidentified antennae on the solar arch, I found an A/B switch for the VHF antenna on the mast.

Almost no range on the VHF until I threw the switch. I haven’t checked yet if anything else is connected to the switch. Bigger fish to fry at the time.

Any obvious reason to have an A/B switch on a VHF antenna? A switch, not a splitter.

[ka4wja]

RB,
Please let us know WHERE you are located, etc....


PART A:

1) We don't know what boat you have?, the size of the boat?, how it is equipped / what equipment is on-board?, where you are located?, where / how has the boat sailed previously? (was it a world-cruiser, island gunkholer, coastal cruiser, etc. was this a "race" boat, a "cruiser", an occasional racer, etc?) was a previous owner a pilot? or a sailboat racer? etc. etc. etc....these are just some of the details that could help us help you.

Some pics of what electronics / comms gear you have on-board will help a lot as well!

Also, what size is the antenna whip, and the lower structure, etc.? {assuming this antenna is fed with coax (coaxial cable of some kind), if the whip is between 7" and 18" long, this tends to suggest an old uhf TRANSIT SatNav antenna....if it's 18" - 24" it suggests it could be VHF antenna, either vhf-airband/vhf-vor, or vhf-LEOSAT-NOAA weather-sat....or maybe vhf-marine/AIS, although a 36" whip would be de rigueur here.....if it is longer than 24" or looks like it could previously been longer than 24", this suggests it could be an HF or VLF active antenna, for LORAN, WeFax, or DGPS-beacon reception....}

And, what type and/or size cable is connected to it? {if it is ethernet/CAT-5/6 cable, this suggests this is an external wi-fi client....if it is coaxial cable, this suggests in could be one of my guesses above....}

Without any of that info, best that I can do are a few guesses.

Originally Posted by RBCurtis

New (to me) boat, first time boat owner.

I have two of these antennae, one on each side of the solar arch.

Can anyone tell me what they are for? I have a VHF antenna on the mast, and a GPS antenna on the rail ...

Thanks!

2) So....on first look, that antenna looks like a 400mhz SatNav antenna....(more precisely, an old 399.968mhz, TRANSIT satellite navigator antenna), or perhaps a 150mhz/400mhz dual-channel TRANSIT SatNav antenna (although, I've only seen these dual-channel SatNav antennas on commercial vessels/survey ships, etc...not on a yacht).

It is similar to this one (which is the streamlined 400mhz satnav "slim-tenna"):





https://www.ion.org/museum/files/TransitBooklet.pdf

Satellite Navigator | Museum of Maritime Navigation and Communication

FYI, the TRANSIT satellite system was retired about 1996, and I haven't seen one of these old SatNav receivers on a boat in many years....probably since the late 1980's / early 90's?

So, while that's what this antenna looks like, I can't image anyone mounting a 25-30 year old SatNav antenna as recently as would've been to be mounted with some modern solar panels....so....


3) My second thought, it could be an active receive antenna for LORAN or WeFax, or DGPS-beacon reception....pretty weird that it would have such a short whip, as these usually have a 4' - 8' whip....but, you never know...


4) Third thought is....they could be NOAA Weather Sat receive antennas....for the 137mhz LEOSATS, like NOAA 19, etc...(although turnstyles and Quadafilar antennas are de rigueur for amateur LEOSAT reception these days, an active whip, especially one angled ~ 15 - 20 degrees from vertical, works well and survives very well offshore/at-sea! And, I have personally used a 20" whip at sea/offshore for NOAA weather sat APT reception, and it worked great, but that was > 20 years ago...)


5) Next, since there are two of them...my original thought taking into account there are two identical (?) antennas, this suggests VOR or VOR/DME reception (VOR is 108-118mhz, with glide-slope at ~ 329-335mhz, DME is ~ 960 - 1215mhz)...now, I haven't seen anyone use VOR/DME on-board boats since racing maxi-yachts of the 1970's and 1980's (maybe up-to the mid-90's, when GPS became cheap and ubiquitous)


6) Of course, they could be VHF antennas for VHF marine, AIS, etc....and, yes, there were some "GPS/VHF-combo" antennas made (which are often packaged with AIS transponders), that look somewhat similar....but, most would have a 3' whip? (as you see now, it is quite important to know what you have on-board....'cuz, all you're getting here are guesses!)


7) Also, there were some other satcom devices, like orbicom that used VHF/UHF....and then there was also AMSC, and a couple others that used both L-band and other freqs(?)....I'd have to strain my brain a bit more to remember the details.


8 ) Of course, these could be wi-fi clients/routers, but that would almost certainly have ethernet cable, not coax, feeding them....so, we'd need to know that up-front...


So, RB....if you could answer all my questions up-top, in detail....and maybe have a look around to see where these antenna cables go, we should be able to help you further! 'Cuz, until then, anything more here from me is guessing.

Bottom line here:
You really need to see what you have on-board...and, if you answer the questions above / post some pics of what you have, figure out where all the wiring goes, etc...we can help...

{Oh, and yes....the other "antenna" you showed, mounted on the rail is your GPS....most likely this IS your entire GPS receiver / antenna in one small "puck" as it's sometimes called....the wire/cable is usually a 3, 4, or 5 conductor cable, which provides "12vdc" power, and outputs GPS data, such as NMEA0183, NMEA2000, SeaTalk, etc.....if the wire connecting this "GPS" is coax, then this is likely a GPS Antenna only, not a GPS "puck", and is likely the external GPS antenna for an AIS transponder....but..
But, fyi...although much less likely, it could also be an S-Band Digital Satellite Radio antenna (for Sirius or XM radio reception, and/or Sirius or XM marine weather info reception)...this would have coaxial cable attached, and usually with SMA or TNC connectors, versus BNS connectors usually used on GPS antennas.....so, again, not knowing what equipment you have on-board, makes figuring all this out mostly guesses! }


Forgive my long-winded answer here....I just reread it, and realized I went a little over-board... LOL
Yes, I'm a long-time offshore sailor....and a confirmed radio nut....started both of these as a kid in the 1960's....first cruise was Bahamas in 1965/66...
Who, although majoring in Physics, has made his living running an electronics/communications company for almost 40 years now (although, I've been semi-retired for years now), so I do tend to go over-board on comms matters.....Have a look at the "stickies" at the top of this "Marine Electronics" page for examples of how verbose I can get when I'm really on a roll!



~~~~~~~~~~~

PART B:

As for having an A/B switch on the VHF-Marine antenna feed....well, it's not common, but not unheard of....sometimes this is to switch-in a back-up antenna (or a low-mounted/rail-mounted antenna, to keep from being disturbed by too much radio traffic from too far away, when all you need is comms within a couple miles)....other times this is to switch between two VHF-marine radios (some have a "cockpit" radio that they have switched-in while underway and another in the cabin or Nav Station for use at anchor/in-port)

My concern is the quality of the switch (Daiwa or Alpha-Delta are good...Bird is great....anything else is probably crap, and than includes "Shakespeare", MFJ, B&W, or any number of unknown/non-name-brand/made-in-China/sold-on-Amazon/ebay switches)....and the quality of cable and connections used on the switch AND that goes up the mast / connects to the antenna!

~~~~~~~~~~~~~


PART C:

All of that crap (sorry....all of those things, devices, tubing, etc.) that are above, and/or above-and-next-to, your solar panels, causes shadows on your solar panels and significantly reduces your solar output! You really need to get rid of it! Especially any wind generator, get rid those....or put it somewhere else.


Gosh, there's a lot more....but, 'til we get the answers to all of those questions, that's all for now.


Fair winds and 73,
John

[smac999]

Looks one an old dgps antenna. To pick up ground station corections.

[Wotname]

Originally Posted by ka4wja

.......
5) Next, since there are two of them...my original thought taking into account there are two identical (?) antennas, this suggests VOR or VOR/DME reception (VOR is 108-118mhz, with glide-slope at ~ 329-335mhz, ..........

FWIW, a VOR antenna would usually be horizontally polarised and no need for them to be paired (on a sailboat that is) - AFAIK.

[RBCurtis]

Originally Posted by ka4wja

RB,
[B]Please let us know WHERE you are located, etc....

PART A:

1) We don't know what boat you have?, the size of the boat?, how it is equipped / what equipment is on-board?, where you are located?, where / how has the boat sailed previously? (was it a world-cruiser, island gunkholer, coastal cruiser, etc. was this a "race" boat, a "cruiser", an occasional racer, etc?) was a previous owner a pilot? or a sailboat racer? etc. etc. etc....these are just some of the details that could help us help you.

Some pics of what electronics / comms gear you have on-board will help a lot as

Gosh, there's a lot more....but, 'til we get the answers to all of those questions, that's all for now.

Fair winds and 73,
John

Thanks John, for the wealth of info provided. The boat is in the Caribbean, and I won’t be back for a few weeks, but I’ll tell you what I know now and follow up later. Your reply reminded me of other devices on board that I didn’t mention previously.

The boat is a 2004 44’ cruising catamaran, originally purchased in Europe, cruised in the Med, and then sailed to the Caribbean about five years ago. No pilots as far as I know.

We have what I think is all original Raymarine nav equipment, including autopilot and analog radar, but no working chart plotter or other display. Refit planned, which is one reason I want to understand what’s there now.

Radio wise, we have the working ICM 324 VHF, and an old Shipmate handset and an Iridium sat phone that I haven’t spent any time figuring out. Wondering now if the Shipmate is also connected to the VHF mast antenna A/B switch.

As far as I know now, no AIS. I don’t know yet what the GPS antenna is connected to, or how it’s connected.

The two identical antennae on the solar arch shown in my original photo are about 10” high in total, including the whip parts, which are only about 3” in length. They look like they’ve been there awhile.

More when I’m back on the boat!