Proper antenna

[N97746]

Was looking to purchase a new VHF and thinking that the SH GX2400 would be the best choice. Most of my time will be spent in coastal Maine and I think the AIS and especially the loud hailer/foghorn options would be essential.
SH claims that I would need an antenna with both VHF and AIS capabilities.
I was wondering what others with the same or similar units were using.
Thanks.

 

[SteveK]

Was looking to purchase a new VHF and thinking that the SH GX2400 would be the best choice. Most of my time will be spent in coastal Maine and I think the AIS and especially the loud hailer/foghorn options would be essential.
SH claims that I would need an antenna with both VHF and AIS capabilities.
I was wondering what others with the same or similar units were using.
Thanks.

Why would you question what SH says about the radio they sell/produce?
If you want AIS and VHF to work, yes you need a combo dual antenna.

 

[N97746]

I do realize that I need a dual antenna as splitters are not recommended with this unit. I was just wondering what others have found to be a good choice for this application.

 

[Turtle Blues]

Yes, that radio has only 1 antenna connection so you need the multi band antenna.
Digital Antenna has a couple of dual antennas in the lower price range. A good one is probably equal to the cost of the radio. I will leave the multiple frequency explanation to a HAM that is better versed in the technical details than I am.

 

[psneeld]

Was looking to purchase a new VHF and thinking that the SH GX2400 would be the best choice. Most of my time will be spent in coastal Maine and I think the AIS and especially the loud hailer/foghorn options would be essential.
SH claims that I would need an antenna with both VHF and AIS capabilities.
I was wondering what others with the same or similar units were using.
Thanks.

I had a Standard Horizon VHF with AIS receive only and a standard VHF antenna worked fine.

I wonder if the recommendation is that the antenna handles the AIS frequencies which many standard antenna do....but I guess there are antennas out there that are better tuned to go up to the AIS frequencies.

Just reviewed the owners manual of the GX2400... on page 7....just says select a standard VHF antenna....but one tuned for both would be a better bet if you want.

file:///C:/Users/psnee/Downloads/GX2400_E_OM_ENG_EM067N201_2005M-BC-2.pdf

 

[N97746]

Yep, that's the problem, cost of a dual use antenna. The SH GX6000 costs a little more but has an outlet for both a VHF and a AIS antenna.
Just trying to get the best bang for my buck given my needs.
Noticed that the owner's manual mentioned the VHF transmits at 155-156 MHz while the AIS does so at 162 MHz. Nothing else is said regarding choice of antenna.
Was hoping that someone using the GX2400 might chime in on what they have done and what their experiences were.

 

[HeadedToTexas]

What's the difference in cost? Is this a buy once, cry once situation?

 

[psneeld]

Hey...a bent coathanger will get you VHF recieve as an antenna..... so a slightly off freq VHF antenna will probably get you OK AIS receive also. The manual says nothing about a dual freq antenna "when selecting an antenna".

Buy the radio if you think it is the one you really want, then plug it into any old VHF antenna and see if the AIS work fine. Then decide whether a fancier antenna is necessary.

Like I posted before, I bought one, read the manual, hooked it to a standard VHF antenna and it seemed to work fine... I was using one of the 17 foot Shakespeare antennas.

 

[N97746]

You make a good point. If it doesn't work with my current antenna I can correct the situation.
On another Forum I belong to a member, like you, is using a Shakespeare VHF antenna and having good results.
Thanks for your advice.

 

[jgwinks]

I'm using a standard VHF antenna on my stand alone AIS receiver and it works just fine. The frequencies are "close enough" for a standard antenna to work. Now if you were transmitting AIS a dedicated purpose built antenna is a better bet.

 

[twistedtree]

Ignore the dual antenna crap. AIS is just another two channels in the VHF marine band. They are up near the top of the band, along with the WX channels, USCG 21 and 22, etc.

An AIS-specific antenna will be tuned more narrowly to the two AIS channels rather than the whole marine band, and provide a slight optimization. But I would emphasize "slight". On my last boat I used a basic 16' VHF antenna for my AIS and I occasionally picked up targets that were literally hundreds of miles away. Now that's an odd-ball situation, but clearly the antenna wasn't getting in the way...

Good cable, and well-made soldered connectors are WAY more important. Don't be tempted by solder-less connectors. They are junk.

 

[SteveK]

Well crud! I had to read the manual. The subject radio ONLY receives AIS. I made the assumption it would transmit your AIS, thus dual antenna needed. Salesperson probably made same assumption.

The MMSI number that can be programmed may only be seen by a vessel you contact using DSC (which apparently not many have). So a coat hangar as well as a standard VHF antenna is all you need.

 

[N97746]

Good point about cable quality and using soldered connections.
Does that mean I'll have to solder the cable to my coat hangar?
Seriously, thanks for all the help guys. Using a Shakespeare 5230, will stick with that.

 

[tpbrady]

TT nailed it. Antennas are in animate objects. The length of the radiating element inside dictates the center frequency. Any frequency either side of the center frequency loses just a little bit of performance, but more transmit or receive energy is lost in connectors and cable.

 

[freshalaska]

Standard vhf antenna works fine on my sh vhf (ais receive) radio.

 

[Helmsman]

VHF specific antennas are tuned to 156 MHz while AIS specific antennas are tuned to 162 MHz. There are 159 MHz tuned antennas out there. I purchased one for my Vesper Cortex,for both radio and VHF and it works well.

https://www.milltechmarine.com/customer_center/Morad-VHF_159HD_spec_sheet_LONG.pdf

 

[High Wire]

AIS transmits on VHF channels 87 and 88. That radio is AIS receive only. Any standard VHF marine band antenna will function just fine. Sure its not perfectly tuned but do you really need that?
I have the S/H GX2200 radio using a Shakespeare 5230 14 ft antenna. It receives AIS signals at 10 miles easily.

 

[Takoradi]

I run a SH GX2400GPS unit, NMEA 2000 connected to a Sitex Navpro 1200F using a Shakespeare Galaxy 5225XT antenna. The SH unit has a serviceable AIS graphical display but I port the AIS hits to the large display Navpro. I also use the Navpro’s GPS because accesses more satellites but the SH GPS works well too. It all works very well. If I had it to do over again, I’d get send/receive AIS as opposed to just receive.

Hope that helps you.

Tak

 

[Capt Ray]

The two AIS frequencies are 161.975 (channel 87B) and 162.025 (channel 88B).

Both are within close proximity to the rest of the +/- 4 dozen marine VHF channels (161.975 - 162.025). So the standing wave ratio (SWR) is predictably LOW across this whole spectrum for all marine VHF antennas... and thus a "different" antenna is not necessary for the AIS channels if you choose to use a splitter.

A "resonant" antenna is best for transmit and receive. But it is only "critical" for transmit. Any commercially available Maine VHF antenna *should* be resonant across this whole frequency range of all the Marine VHF channels.

I do not know of any Marine VHF radios that have two antenna ports. But there are several AIS transponders that have dual antenna ports so the AIS transponder can "share" the same antenna with a VHF radio.

e.g. We have a Raymarine VHF 73 radio that shares the same Shakespeare VHF Marine antenna as the EmTrak B924 AIS transponder... which has an "antenna splitter" built-in. So the antenna's coax screws into the EmTrack 924, then there is a short coax cable that goes from the EmTrack B924 to the VHF radio.

This works very well. The Raymarine VHF 73 has AIS receive only. But it did not take us long on our Great Loop trip to realized we wanted to add AIS transmit. Thus the EmTrack B924 addition.

Some more details here: https://shellerina.com/2023/09/19/ais-ing-again/

I am a big believer in AIS. Good technology. Good investment.
Hope this info helps.


Ray Sirois
N1RY (Extra Class Amateur Radio Operator / ARRL Registered Instructor)

 

[MacPhid]

The two AIS frequencies are 161.975 (channel 87B) and 162.025 (channel 88B).

I do not know of any Marine VHF radios that have two antenna ports. But there are several AIS transponders that have dual antenna ports so the AIS transponder can "share" the same antenna with a VHF radio.

Ray Sirois
N1RY (Extra Class Amateur Radio Operator / ARRL Registered Instructor)

Ray,

The Simrad RS40-B has a separate connector for an AIS antenna and requires it.
The RS40-B is a full transceiver, they also have the RS40 model which is receive only.

James

 

[CaptTom]

I'm going to put in a plug for AIS transmit. If you're going to be playing with the "big boys" (commercial shipping) it'll be worth it. And of course then you can add a dedicated antenna for the AIS transceiver, no dual antenna or splitter needed. I've never regretted going this route.

I think too many people are sold a VHF radio "with AIS" without really understanding that it's receive-only. They check the box and think they "have" AIS. Nope.

 

[Cortez]

Coax is more important

Almost all VHF antennas are going to be OK for the AIS.

More important for a new install is using an excellent coax, like marine RG213, and one connection (at most). Never add a splitter. This will keep loss and standing wave to a minimum. With correct coax and minimal standing wave in the line, low power will usually work to the limit of visibility; the normal range of VHF.
When there is a standing wave in the line, caused by mismatched impedance and/or poor coax, the radio LOWERS ITS POWER to protect its components. Going to high power does nothing because the radio must protect itself from the standing wave.
Good coax is a one-time expense and well-worth the cost.

 

[Capt Ray]

The two AIS frequencies are 161.975 (channel 87B) and 162.025 (channel 88B).

Both are within close proximity to the rest of the +/- 4 dozen marine VHF channels (161.975 - 162.025). So the standing wave ratio (SWR) is predictably LOW across this whole spectrum for all marine VHF antennas... and thus a "different" antenna is not necessary for the AIS channels if you choose to use a splitter.

A "resonant" antenna is best for transmit and receive. But it is only "critical" for transmit. Any commercially available Maine VHF antenna *should* be resonant across this whole frequency range of all the Marine VHF channels.

I do not know of any Marine VHF radios that have two antenna ports. But there are several AIS transponders that have dual antenna ports so the AIS transponder can "share" the same antenna with a VHF radio.

e.g. We have a Raymarine VHF 73 radio that shares the same Shakespeare VHF Marine antenna as the EmTrak B924 AIS transponder... which has an "antenna splitter" built-in. So the antenna's coax screws into the EmTrack 924, then there is a short coax cable that goes from the EmTrack B924 to the VHF radio.

This works very well. The Raymarine VHF 73 has AIS receive only. But it did not take us long on our Great Loop trip to realized we wanted to add AIS transmit. Thus the EmTrack B924 addition.

Some more details here: https://shellerina.com/2023/09/19/ais-ing-again/

I am a big believer in AIS. Good technology. Good investment.
Hope this info helps.


Ray Sirois
N1RY (Extra Class Amateur Radio Operator / ARRL Registered Instructor)

Here is the intended link:

 

[Iggy]

Let me tell you a story that might help others out.

I bought a Vesper 800 and a VHF antenna a few years ago for my past boat. All good with no problems.

Sold the boat and took the Vesper with me leaving the antenna. Install the Vesper in the new boat with a new antenna. Now friends are tell me that I need to be in a mile and half to see me on AIS. Using the Bluetooth app, I can see a swr error.

I called Vesper and the short story is. That some VHF antennas can be tuned for ether both (broadband), just AIS or just VHF.

I lucked out on the my old boat buying a broadband without knowing it. So the antenna should be tuned to how you setup your VHF and AIS units.

For the benefit of others. The SWR error meant that that there was a mismatch between the antenna and transmitter. Some of the signal/power was being sent back to the transmitter. If enough power goes back, the transmitter will burn it self out.

You can buy a SWR meter to test your setup. A cheap and good investment.

 

[psneeld]

Let me tell you a story that might help others out.

I bought a Vesper 800 and a VHF antenna a few years ago for my past boat. All good with no problems.

Sold the boat and took the Vesper with me leaving the antenna. Install the Vesper in the new boat with a new antenna. Now friends are tell me that I need to be in a mile and half to see me on AIS. Using the Bluetooth app, I can see a swr error.

I called Vesper and the short story is. That some VHF antennas can be tuned for ether both (broadband), just AIS or just VHF.

I lucked out on the my old boat buying a broadband without knowing it. So the antenna should be tuned to how you setup your VHF and AIS units.

For the benefit of others. The SWR error meant that that there was a mismatch between the antenna and transmitter. Some of the signal/power was being sent back to the transmitter. If enough power goes back, the transmitter will burn it self out.

You can buy a SWR meter to test your setup. A cheap and good investment.

On top of of your story....I think enough others have voiced that if you have JUST an AIS receive radio, any decent VHF antenna will work fine..... BUT....if you have an AIS tranceiver....then the tuned to AIS antenna would be the better choice.

I believe the OP was asking about an AIS receive VHF radio.

 

[Iggy]

On top of of your story....I think enough others have voiced that if you have JUST an AIS receive radio, any decent VHF antenna will work fine..... BUT....if you have an AIS tranceiver....then the tuned to AIS antenna would be the better choice.

I believe the OP was asking about an AIS receive VHF radio.

Point will taken.

I just thought that others and maybe the Op may upgrade could benefit from my troubles. Saving others time and money. Sorry you feel this way.

 

[Bob Cofer]

I have this antenna (VHF-159) and use it for both VHF and AIS. Very durable and made in the US.

https://www.morad.com/pages/vhf-antennas

 

[AnsleyS]

Question

What is the proper procedure to cut out extra VHF antenna wire? Any tuning needed?

 

[psneeld]

What is the proper procedure to cut out extra VHF antenna wire? Any tuning needed?

Usually in either the antenna installation instructions or the radio owners manual it will say the minimum length of cable required.