VHF Marine Radio Antennas

[annette315]

Hi,

I'm a marine radio newbie and I have a few questions. TIA for answering them!

1. Does coax cable come included with VHF antennas, or does it need to be purchased separately?

2.Do all mounts work with all antenna types?

Thanks,
Annette

 

[cedarjunki]

Re: VHF Marine Radio Antennas

Hi,

I'm a marine radio newbie and I have a few questions. TIA for answering them!

1. Does coax cable come included with VHF antennas, or does it need to be purchased separately?

2.Do all mounts work with all antenna types?

Thanks,
Annette

1. depends on which antenna you buy.

2. also depends on which antenna for which mount needed.

3. nothing about boating is made simple

 

[turbinedoctor]

Re: VHF Marine Radio Antennas

When looking at antennas try to pick one that does come with the coax attached to it. That way there should be one less connection you need to worry about. The end that connects to your radio may not have the connector attached to it but thats OK. This allows you to run your cable and cut off the excess. The shorter the cable length the better but leave a foot or two of slack. Then solder the connector on and connect to your radio.

When dealing with marine VHF radios and antennas, put more thought into which is the best antenna for your situation then the radio. The fixed mount radios can only put out 25 watts so it is up to the antenna to try to get as much power as possible out to the people you are calling.

 

[bruceb58]

Re: VHF Marine Radio Antennas

One more thing...if the antenna comes with cable, the instructions may say not to cut the length down even if you don't need the extra length.

 

[turbinedoctor]

Re: VHF Marine Radio Antennas

Thats a good point Bruce. Luckly mine said it was OK to do so. Always read the instructions first.

 

[cedarjunki]

Re: VHF Marine Radio Antennas

heres some good info...

http://www.catfleet21.org/rigging/June.htm

 

[annette315]

Re: VHF Marine Radio Antennas

Thanks so much for your replies. So what I understood is some antennas come with cables and some do not? Is that correct?
Does it just depend on the brand - or the antenna?

Also, what about the different types of mounts - do they work with any antenna at all?

 

[Fl_Richard]

Re: VHF Marine Radio Antennas

Antennas can come with or without cable even in the same line. Sometimes you can order them either way, sometimes not.

I like cable installed; but on a 60 footer the cable is a waste.

Most antenna mounts will connect to any antenna.

 

[annette315]

Re: VHF Marine Radio Antennas

Thanks!!!

 

[Boatist]

Re: VHF Marine Radio Antennas

Most VHF 8 foot 6 DB gain antennas come with the coax. When you go on line the add should tell you if it comes with Coax or not.
Most come with about 20 foot of coax. Better antenna will usually have RG 8X coax which is lower loss then the RG-58 on cheaper antennas.

Most antennas will mount on most Mounts but if you get a 8 foot top of the line antenna like a Shakespeers 5225 then plan on getting a good solid mount.
Rail mounts or the nylon mounts would not be a good choice. If your a salt water boater go with a Stainless Steel mount and put a good plate on the underside of the deck or at least very large washers.

Most VHF 8 foot antenna are half wave and you can cut the coax but never shorter the 3 feet. Myself I leave it long enough to reach every place on the boat that I could mount a Radio. You may some day buy a second radio or move it to a different spot. The Line loss in 20 feet of Coax is not enough to worry about even with RG-58.

 

[rad1026]

Re: VHF Marine Radio Antennas

Not trying to hijack the thread but I hope this question fits in with the theme here. There is a lot of good information. What is the difference between a marine VHF antenna and a regular vehicle CB antenna. I just purchased a marine VHF radio for our trip to Lake Powell and I have a Wilson no ground CB antenna sitting in the garage. Can I use the CB antenna? Thanks!

 

[DianneB]

Re: VHF Marine Radio Antennas

No.

CB radios work in the 27 MHz band and VHF marine in around 160 MHz.

The antenna are totally different (electrically).

 

[Boatist]

Re: VHF Marine Radio Antennas

I agree you can not use a CB antenna for VHF Marine. The transmitter would shut down or burn up. Big difference between 27 MHZ and 158 MHZ.
By the way more inportant to get the best antenna you can find than the best radio. That said if your an off Shore boater or boat in areas where VHF radio is used by many boats I would buy a unit with CLASS D DSC instead of SC101.

 

[88phantom]

Re: VHF Marine Radio Antennas

Speaking of the best antenna, what is recommended? I am a longtime radio engineer and would like a good antenna for my boat. I am not impressed with the 1.5:1 VSWR that shakespeare advertises their centennial line. That is a really poor match IMO. I have also been moving away from shakespear fishing products because they are so cheap that we break them right away or find they work poorly.

 

[turbinedoctor]

Re: VHF Marine Radio Antennas

Phantom I am sorry to hear you have bad luck with Shakepere. I have the 5202 Contintanal and couldn't be happier. I get great reception, transmission and even had some step on it, when boarding my boat, without damage.

I guess there are lemons in antennas too.

 

[AguaSki]

Re: VHF Marine Radio Antennas

Shakespeare makes a fine antenna. Many will argue that a Shakespeare antenna is the best. If you have made up your mind that you don't want a Shakespeare, then look into Digital brand antennas. I think the Digital 529-VW antenna is a very good antenna that will not disappoint.

 

[Boatist]

Re: VHF Marine Radio Antennas

Like anything you get what you pay for.
I started with a shakespears 497 which was 8 foot 6 DB gain and it worked ok but after a few years out in the ocean in area where there were a lot of boats I noticed other boat were recieving stations I could not here.

So I got a shakespears 5225-XT and could not belive the diference. Now I could here lots of stations other could not hear. Also talk to Coast Guard from 80 plus miles away when they put out a request if anyone elese heard a MayDay Call to contact them. I did not think I could reach them do to distance but did hear the SOS electronic Mayday call so gave them a call. They wanted to know my position.
They heard the call but had no way to tell where it was. This was back when some radios has a button that would send a automatic morse Code SOS. It would give no position of anykind of identifer. Basicly a bad idea for a MayDay call. Kids loved to push the button. Anyway since my boat to boat range is about 10 miles it told the Coast Guard the basic position of the SOS. Coast Guard San Francisco herd the call but they here 80 plus miles in every direction because antenna is 3000 feet high.

Today of course DSC radios put out a distress call on Channel 70 which I belive is only 1 watt so a good 6DB gain antenna is a must for saftey.

I have also heard some who like digtial antennas but have not seen them My self.

My antenna has a VSWR of about 1.3 to one on channel 22 and have not seen any channel over 1.4 to 1. Have not tested on channel 16.

The longer 9 DB antenna are not recomended on small boats in the ocean because the horz beam is so narrow the radio will drop out as go over swells or rock and roll.

 

[jhebert]

Re: VHF Marine Radio Antennas

Concern about a VSWR of 1.5:1 is not justified in a VHF Marine Band radio antenna. There is little if anything to be gained from lower VSWR.

Antenna height is of more importance in determining range than antenna gain. Antenna gain always comes at the expense of antenna pattern. On a small boat an antenna with a broad and uniform pattern is preferable to one with a narrow pattern with deep nulls.

Ratings for gain of antennas from VHF Marine Band manufacturers is quite fanciful and appears to generally be inflated.

I give my personal recommendations on antennas for a small boat installation in

http://continuouswave.com/whaler/reference/VHFAntenna.html

The general topic of VHF Marine Band radio antennas is presented in

http://continuouswave.com/whaler/reference/antennaVertical.html

An analysis of VHF Marine Band radio range by predicting path loss is given in

http://continuouswave.com/whaler/reference/pathLoss.html

This approach is in contrast to the usually cited method of radio horizon calculation based solely on antenna height. It is well known and easily demonstrated that VHF radio communication beyond the range of the radio horizon is possible and frequently occurs.