I have been following the thread about handheld VHF radios. I have ordered an ICOM M-88. I have not received it yet, so I hope I am not getting ahead of my self. I know that the VHF system uses line of sight to send and receive a signal. Can a remote antenna be used with your handheld unit? If so how is it done, and where is the best location for the antenna? As I am sure you can see I am now to this, and I look forward to the answers. I felt that this topic should be on a new thread, so here goes. Dale
VHF handheld and remote antennas
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Yes and No
Ahoy Dale; It would be possible to unscrew the exisiting antenna and add another VHF antenna with a special coax connector. I would not do it though. It is a brand new radio and you could void the warranty. That said the antenna location and the type of antenna you want to apply depends on the type of boat you have. If you have a sailboat use a 3db gain antenna and mount it on top of the mast. This gives the best performance, due to the heeling motion of a sailboat. If you are in a power boat and because they don't heel much, and they don't have a real high place to mount them, go with at least 9db gain antenna. Fair Winds Cap'n Dave
Ahoy Dale; It would be possible to unscrew the exisiting antenna and add another VHF antenna with a special coax connector. I would not do it though. It is a brand new radio and you could void the warranty. That said the antenna location and the type of antenna you want to apply depends on the type of boat you have. If you have a sailboat use a 3db gain antenna and mount it on top of the mast. This gives the best performance, due to the heeling motion of a sailboat. If you are in a power boat and because they don't heel much, and they don't have a real high place to mount them, go with at least 9db gain antenna. Fair Winds Cap'n Dave
D
Don
Couple of comments
First, you can do it but it may not be worth the effort because of the loss of the coax. Unless you use hard line coax which is impractical, the loss at VHF frequencies for even 50 ft of typical coax (RG 8 or 58 or 214) would far exceed any perceived gain in signal strength obtained from elevating the antenna. Second, there is no such thing as a "gain" antenna. Antennas don't produce or amplify power. As they say, "Let the buyer beware"... Don
First, you can do it but it may not be worth the effort because of the loss of the coax. Unless you use hard line coax which is impractical, the loss at VHF frequencies for even 50 ft of typical coax (RG 8 or 58 or 214) would far exceed any perceived gain in signal strength obtained from elevating the antenna. Second, there is no such thing as a "gain" antenna. Antennas don't produce or amplify power. As they say, "Let the buyer beware"... Don
remote antennae
Yes, of course, assuming you bought a radio with a removable antenna. I can't tell from the catalog cuts available whether yours is removable. You'll need a ham or a ham shop to help. Your project amounts to making or buying almost any kind of antenna you want (including a rubber duckie type like probably came with your radio, and an extension cord made of the proper coaxial cable and a couple of termination jacks, one like the one on your antenna, and one like on your radio. There are several types of antennas you can make for nearly free that work very well. Research on the web. I've given one site to get you started. Then you need to tune your antenna (impedance matching) to your transmitter. Talk to the ham shop about how to do this. You'll have to buy or borrow an impedance matching instrument. It's critical for the life of your radio's output amplifier, and effects the power of your output signal. I made a free antenna and a 20' extension cord for it, took it camping, and draped the antenna from a high branch on a tree. Then I talked to a fellow 40 miles away on a 5 watt handheld 2m radio not very different from yours. Just an anecdote, but that is quite possible using your mast for the "tree". I've tested several homemade and store-bought models on my hangglider. Almost anything works better than the one that came with my Yaesu, but from 1000' up, they all worked well enough, and I'm back to using a commercial rubber duck antenna. btw, hope you didn't pay too much. $280 here: http://www.marinedeal.com/product_p/c15409.htm
Yes, of course, assuming you bought a radio with a removable antenna. I can't tell from the catalog cuts available whether yours is removable. You'll need a ham or a ham shop to help. Your project amounts to making or buying almost any kind of antenna you want (including a rubber duckie type like probably came with your radio, and an extension cord made of the proper coaxial cable and a couple of termination jacks, one like the one on your antenna, and one like on your radio. There are several types of antennas you can make for nearly free that work very well. Research on the web. I've given one site to get you started. Then you need to tune your antenna (impedance matching) to your transmitter. Talk to the ham shop about how to do this. You'll have to buy or borrow an impedance matching instrument. It's critical for the life of your radio's output amplifier, and effects the power of your output signal. I made a free antenna and a 20' extension cord for it, took it camping, and draped the antenna from a high branch on a tree. Then I talked to a fellow 40 miles away on a 5 watt handheld 2m radio not very different from yours. Just an anecdote, but that is quite possible using your mast for the "tree". I've tested several homemade and store-bought models on my hangglider. Almost anything works better than the one that came with my Yaesu, but from 1000' up, they all worked well enough, and I'm back to using a commercial rubber duck antenna. btw, hope you didn't pay too much. $280 here: http://www.marinedeal.com/product_p/c15409.htm
With a stainless stubby on a forty foot mast
and an 8' FG on a center console arch I've successfully communicated with large base stations up to 60 miles over open ocean. These are CG Long Beach & San Diego about 120 miles apart from about halfway between. The big base stations like these that generally have a large ant. at altitude can communicate that far with a 25 watt and good ant. Boat to boat about half that unless it's a Navy warship then we're back up to 50-60 miles. Harbor Patrols usually just have an ant. high on their building and are good for about 25 miles on your big radio. With a handheld you can communicate well from 6 to 12 miles with average harbor patrol set-up, sometimes receives up to 25 or 30 miles from big base high up. Besides ant length & height 25 watts beats 5 anyday, for day to day use handheld gets the most use cause you are close usually to who you want to talk to. If you are requesting assistance when all you can see is water you really want that mast top and a 25 watt.
and an 8' FG on a center console arch I've successfully communicated with large base stations up to 60 miles over open ocean. These are CG Long Beach & San Diego about 120 miles apart from about halfway between. The big base stations like these that generally have a large ant. at altitude can communicate that far with a 25 watt and good ant. Boat to boat about half that unless it's a Navy warship then we're back up to 50-60 miles. Harbor Patrols usually just have an ant. high on their building and are good for about 25 miles on your big radio. With a handheld you can communicate well from 6 to 12 miles with average harbor patrol set-up, sometimes receives up to 25 or 30 miles from big base high up. Besides ant length & height 25 watts beats 5 anyday, for day to day use handheld gets the most use cause you are close usually to who you want to talk to. If you are requesting assistance when all you can see is water you really want that mast top and a 25 watt.
Rebate
Hi Dale - I have an M88 myself and am pleased with it. I use it in the cockpit and keep a cheap hard wired one below at the nav station with a 3' antenna at the top of the mast. The battery life is great so I find myself using the handheld most of the time. Just in case you didn't know, there is a $50 mfg rebate on the M88 through January 2006. Best, Trevor
Hi Dale - I have an M88 myself and am pleased with it. I use it in the cockpit and keep a cheap hard wired one below at the nav station with a 3' antenna at the top of the mast. The battery life is great so I find myself using the handheld most of the time. Just in case you didn't know, there is a $50 mfg rebate on the M88 through January 2006. Best, Trevor
So I left the word with out
True, antennas dont produce gain. This one stumps even some of the most advanced RF engineers, that is, the "gain" of an antenna. Even the law states that the "Effective Radiated Power (ERP) will not exceed..." and this is based on the input into the antenna multiplied by the antenna gain. There is this concept that, the moment they exhibit gain, antennas magically create power within themselves. This is not the case. If one examines an antenna it will be noted it is constructed of basic materials, the best being gold, silver, copper, then aluminium following on. These materials in themselves cannot create power. Before I go into any explanations there are some terms that need definition so-as to assist in the explanation of antenna gain. decibel (dB): unit of measure of loss or gain. Gain has a positive value, loss has a negative value, and is equal to 10*log(Pout/Pin) Antenna Gain: The relative increase in radiation at the maximum point expressed as a value in dB above a standard, in this case the basic antenna, a ½-wavelength dipole (as in Two-Poles) by which all other antennas are measured. The reference is known as 0dBD (zero decibel referenced to dipole). An antenna with the effective radiated power of twice the input power would therefore have a gain of 10*log(2/1) = 3dBD. I can go on if you wish. Fair Winds Cap'n Dave
True, antennas dont produce gain. This one stumps even some of the most advanced RF engineers, that is, the "gain" of an antenna. Even the law states that the "Effective Radiated Power (ERP) will not exceed..." and this is based on the input into the antenna multiplied by the antenna gain. There is this concept that, the moment they exhibit gain, antennas magically create power within themselves. This is not the case. If one examines an antenna it will be noted it is constructed of basic materials, the best being gold, silver, copper, then aluminium following on. These materials in themselves cannot create power. Before I go into any explanations there are some terms that need definition so-as to assist in the explanation of antenna gain. decibel (dB): unit of measure of loss or gain. Gain has a positive value, loss has a negative value, and is equal to 10*log(Pout/Pin) Antenna Gain: The relative increase in radiation at the maximum point expressed as a value in dB above a standard, in this case the basic antenna, a ½-wavelength dipole (as in Two-Poles) by which all other antennas are measured. The reference is known as 0dBD (zero decibel referenced to dipole). An antenna with the effective radiated power of twice the input power would therefore have a gain of 10*log(2/1) = 3dBD. I can go on if you wish. Fair Winds Cap'n Dave
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