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Yacht Rf ground and radials
I want to set up a hf antenna for my sailboat.
I have read various guides from Icom etc. They suggest running copper foil to a Dynaplate and use sea water as the ground. How can this work when the Dynaplate is below sea water? Is sea water equal to copper wire radials as a RF ground system? Does sea water make a good enough ground without radials? How can a piece of copper metal about 1 ft square equal several radials laying on the boats deck? Why do i have to use copper foil when most other people suggest using ordinary copper wire? Over seawater what would be the best number of radials to use considering that maximum length i can run is 40 ft. I am planning to use a backstay antenna with a SGC 230 Tuner. All ideas and comments appreciated. Will |
Yacht Rf ground and radials
I don't think Icom would jack you around about this, do you really?
Marine radios are a large part of their business and they do know their business. Uhmmm...this isn't one of those ionosphere posts is it? Butch Will wrote: I want to set up a hf antenna for my sailboat. I have read various guides from Icom etc. They suggest running copper foil to a Dynaplate and use sea water as the ground. How can this work when the Dynaplate is below sea water? Is sea water equal to copper wire radials as a RF ground system? Does sea water make a good enough ground without radials? How can a piece of copper metal about 1 ft square equal several radials laying on the boats deck? Why do i have to use copper foil when most other people suggest using ordinary copper wire? Over seawater what would be the best number of radials to use considering that maximum length i can run is 40 ft. I am planning to use a backstay antenna with a SGC 230 Tuner. All ideas and comments appreciated. Will |
Yacht RF ground and radials
Will wrote:
"Does sea water make a good enough ground without radials?" It`s the best you can get in a boat at sea, The point is to get a good connection to the sea. You don`t need radials for that. That`s why a thin copper plate is recommended. Copper is durable and poisonous to sea organisns which may foul the surfaces of other materials. Skin effect applies. Bolting to a spot inside a metal hull means the RF must travel from the bolt location inside the hull (it can`t penetrate the hull) to an edge where it reaches from the inside surface to the outside surface and thence to the waterline. DC resistsance of a conductor is resistivity x length divided by crossection. AC resistance is more but proportioned to the DC resistance. A large crossection or area produces a low resistance. That`s why the plate is better for contacting the water than a wire. Its also why the seawater has a low resistance despite a higher resistivity than copper. The huge crossection of seawater has very low resistance in most cases and its reactance is low too. Low resistance and low reactance make a good path for RF. Best regards, Richard Harrison, KB5WZI |
Yacht Rf ground and radials
A 6" square plate makes an adequate ground when immersed in salt sea
water. That is unless the transmitter power exceeds 10 kW. |
Yacht Rf ground and radials
On Tue, 23 May 2006 23:44:50 +1000, Will
wrote: They suggest running copper foil to a Dynaplate and use sea water as the ground. How can this work when the Dynaplate is below sea water? Hi Will, Below is better than above, to say the least. How much below is immaterial. Is sea water equal to copper wire radials as a RF ground system? Skip the pursuit of the Holy Grail in radials, this may lead you to start carrying buckets of dirt which screws up buoyancy. Why do i have to use copper foil when most other people suggest using ordinary copper wire? Probably more surface area. All ideas and comments appreciated. How good (or poor) sea water is for matching and loss, is seeing the glass 3/4's empty. How good sea water is for propagation is seeing the pitcher nearby and filling your glass several times. 73's Richard Clark, KB7QHC |
Yacht Rf ground and radials
In article ,
Butch Magee wrote: I don't think Icom would jack you around about this, do you really? Marine radios are a large part of their business and they do know their business. Uhmmm...this isn't one of those ionosphere posts is it? Butch Will wrote: I want to set up a hf antenna for my sailboat. I have read various guides from Icom etc. They suggest running copper foil to a Dynaplate and use sea water as the ground. How can this work when the Dynaplate is below sea water? Is sea water equal to copper wire radials as a RF ground system? Does sea water make a good enough ground without radials? How can a piece of copper metal about 1 ft square equal several radials laying on the boats deck? Why do i have to use copper foil when most other people suggest using ordinary copper wire? Over seawater what would be the best number of radials to use considering that maximum length i can run is 40 ft. I am planning to use a backstay antenna with a SGC 230 Tuner. All ideas and comments appreciated. Will No, Not an Ionsphere Post, just a guy who has no clue about the technology that he wants to use, and he is asking questions, trying to learn. From the replys he has received so far, he is finding out that 99% of the hams, don't have a clue about MF/HF Marine Radio Antenna systems Design, either. I suggest that he head on over to rec.boat.electronics, and ask Larry, Gary S., Old Chief Lynn, or one of the other Old Salts, that have been doing these installations for decades, and have the experience in the technology being asked about. Most hams think that MF/HF Marine Radio Antenna Systems design should follow the same rules that Land Startions use. Well that isn't the case, and usually ends up is a "**** Poor", marginal system that only talks "when the Band is open", and "when the Band is open" even a wet noodle will radiate enough to communicate. Me |
Yacht Rf ground and radials
Richard Clark wrote:
On Tue, 23 May 2006 23:44:50 +1000, Will wrote: They suggest running copper foil to a Dynaplate and use sea water as the ground. How can this work when the Dynaplate is below sea water? Hi Will, Below is better than above, to say the least. How much below is immaterial. Is sea water equal to copper wire radials as a RF ground system? Skip the pursuit of the Holy Grail in radials, this may lead you to start carrying buckets of dirt which screws up buoyancy. Why do i have to use copper foil when most other people suggest using ordinary copper wire? Probably more surface area. All ideas and comments appreciated. How good (or poor) sea water is for matching and loss, is seeing the glass 3/4's empty. How good sea water is for propagation is seeing the pitcher nearby and filling your glass several times. 73's Richard Clark, KB7QHC A few additional questions along these lines for the group (with some paraphrasing): 1. What is the skin depth in salt water at 14 MHz? How would this affect a ground plate at four feet below the surface? 2. What would the ohmic losses be over a one square foot by 33 foot path through salt water? 3. How well would the ground plate work on fresh water bodies, such as much of the Chesapeake, the Great Lakes, and various rivers and tributaries often used by cruisers? How would it compare with radials over fresh water? 4. Can anyone cite a published and reproducible study in which the RF losses through salt water were measured and compared with losses through one or more copper wire "radials" on or below deck of a typical cruising vessel? Or is there a published theoretical analysis of this comparison? Looking for more than the casual, anecdotal stuff. 5. Will a four foot length of wire dropped into sal****er provide a "good" RF "ground" and on what is the answer based? I need enlightenment! Thanks, and 73, Chuck NT3G |
Yacht Rf ground and radials
Icom needs to modernize their thinking and get rid of their "old school" installation guides. Wire radials are the way to go on your sailboat. Not copper foil or wide copper strips, just plain old 14 gauge wire radials. I suggest you read some of the threads about this on the Maritime Mobile Ham Forum from people with real world experience with marine HF installations. You'll find the answers to your questions the http://cruisenews.net/cgi-bin/mmham/webbbs_config.pl Eric "Will" wrote in message ... I want to set up a hf antenna for my sailboat. I have read various guides from Icom etc. They suggest running copper foil to a Dynaplate and use sea water as the ground. How can this work when the Dynaplate is below sea water? Is sea water equal to copper wire radials as a RF ground system? Does sea water make a good enough ground without radials? How can a piece of copper metal about 1 ft square equal several radials laying on the boats deck? Why do i have to use copper foil when most other people suggest using ordinary copper wire? Over seawater what would be the best number of radials to use considering that maximum length i can run is 40 ft. I am planning to use a backstay antenna with a SGC 230 Tuner. All ideas and comments appreciated. Will |
Yacht Rf ground and radials
You mean the "Maritime" mis information forum? Looks like some real world BS artists on there. Would you make those radials on the boat resonant or not? If resonant, how would you know? How much more inductance would a ground wire have than copper foil. 73 Gary K4FMX On Tue, 23 May 2006 21:11:29 -0400, "Eric Fairbank" wrote: Icom needs to modernize their thinking and get rid of their "old school" installation guides. Wire radials are the way to go on your sailboat. Not copper foil or wide copper strips, just plain old 14 gauge wire radials. I suggest you read some of the threads about this on the Maritime Mobile Ham Forum from people with real world experience with marine HF installations. You'll find the answers to your questions the http://cruisenews.net/cgi-bin/mmham/webbbs_config.pl Eric "Will" wrote in message ... I want to set up a hf antenna for my sailboat. I have read various guides from Icom etc. They suggest running copper foil to a Dynaplate and use sea water as the ground. How can this work when the Dynaplate is below sea water? Is sea water equal to copper wire radials as a RF ground system? Does sea water make a good enough ground without radials? How can a piece of copper metal about 1 ft square equal several radials laying on the boats deck? Why do i have to use copper foil when most other people suggest using ordinary copper wire? Over seawater what would be the best number of radials to use considering that maximum length i can run is 40 ft. I am planning to use a backstay antenna with a SGC 230 Tuner. All ideas and comments appreciated. Will |
Yacht Rf ground and radials
Will writes:
I want to set up a hf antenna for my sailboat. I have read various guides from Icom etc. They suggest running copper foil to a Dynaplate and use sea water as the ground. How can this work when the Dynaplate is below sea water? Is sea water equal to copper wire radials as a RF ground system? Does sea water make a good enough ground without radials? How can a piece of copper metal about 1 ft square equal several radials laying on the boats deck? Why do i have to use copper foil when most other people suggest using ordinary copper wire? Over seawater what would be the best number of radials to use considering that maximum length i can run is 40 ft. I am planning to use a backstay antenna with a SGC 230 Tuner. All ideas and comments appreciated. Well, I don't have personal experience with this. There is a chapter in the ARRL antenna book, and it basically agrees with ICOM. As to radials - two comments. First - how do you make sure that they don't get in the way. And that RF currents won't be a hazard to people. Second - there are plenty of wires on a yacht. How do the wires know whether or not they are supposed to act as radials? *If* there is a better alternative to the traditional backstay using seawater as ground, it might be the vertical dipole. Feeding would be tricky, but for single band operation, you could probably feed it like a J-Pole. I don't see how to make a multiband variant. And you get the high voltage points close to the deck, which doesn't sound like a good idea in a damp and salty environment. There are also people who hoist a horizontal dipole when needed. OK for recreational radio, not if you need to be able to communicate in rough weather. Of course, square riggers are beautiful, and you could use the yard-arms as a stacked yagi. 73 LA4RT Jon |
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