My experience over the last 30 years or so has shown that the best HF antenna
for a sailboat (sloop) has not been mentioned or discussed yet in this thread. The antenna
that I have found that consistently out performs any other sailboat antenna is called a sloper. It is electrically the opposite of the regular backstay antenna discussed here in that you connect your transmitter's COAX feedline at the TOP of your insulated backstay. You do this by using a radio rigging
insulator mounted right at the masthead (marine eye on a toggle...see photo). Now, I can hear you saying; If this is such a great antenna then why don't more people know about it and why isn't everyone using one? Well...there's a couple of drawbacks with this antenna but they aren't about the antenna. They are about the setup desired, and the end users. Here's why;
1.) The sloper MUST be connected to the backstay right at the masthead using coax cable not a single
wire feedline. That let's out all the users that require automatic antenna tuners with single
wire output fittings. Marine
auto antenna tuners are simply not set up to tune an antenna fed with coax cable. Sorry...
2.) Because of number one, you must use a manual antenna tuner. That lets out users that don't want to take the trouble to learn how to tune their antenna each time they change bands. It takes a bit of practice, or a knack if you will, to learn to use the manual tuners quickly. But once you get the hang of it, (and write down your settings for each band) it's not a big deal at all. So folks that like to push the button and talk...well...sorry.
3.) You have to install the sloper when your mast
is down because you need to feed the coax cable up inside the mast
to the masthead through the mast's PVC wiring
tube. (you do have one of those I hope)
Now, on the plus side?
1.) You don't need to worry about trying to hook up a ground counterpoise
inside the hull
of your boat because the sloper uses the rest of the mast, upper shrouds, lower shrouds, and anything that is grounded to the mast as it's counterpoise
. (the braid of the coax cable gets connected to the shrouds with a stainless strap---see photo) In essence the backstay now "sees" the rest of the entire rig as it's counterpoise and is USING the rigging
to benefit instead of the rigging being in the way and absorbing some of your signal when you connect your backstay at the bottom.
2.) You won't have hot RF running around your electrical
up lights and giving you RF burns if you touch something that the signal is using for it's counterpoise because your counterpoise is no longer in the boat....it's in the rigging.
2.) But lastly, the best part and why the sloper antenna radiates so well, (for you electronic geeks out there) is that the current
loop of the sloper (the part that radiates your signal out into space) is now way up at the masthead and not down in a locker below decks where you mounted your automatic antenna tuner. (the current
loop in a bottom fed auto-tuned antenna is near the antenna tuner and bottom portion of the antenna (your backstay). For anyone interested in the technical reasons why, there are volumes written on voltage loops and current loops in unbalanced non-resonant coax fed antennas---but we won't be going into that here. Suffice to say one can "see" a lot further from the top of their mast than from poking their head
out the lazzarette!
supplied here is of the masthead fittings on my sloper I installed on my old Rawson
30 that finished up a seven year circumnavigation
. The sloper fared very well and there were no problems at all caused by using this "upside-down" antenna. If it's hard to see in the photo
, but the large black cable exiting the mast is RG-213x coax cable with a PL-259 plug
on the end. That PL-259 plug
screws into a SO-239 female coax connector that is mounted on a .040" stainless grounding strap that is screwed to the masthead, and also runs up and over the masthead and is clamped with hose clamps to the headstay which insures that the braid of the coax cable makes a good solid ground connection to the rigging. In reality ALL the rigging measures as ground on the braid side of the coax cable so the entire rig becomes the counterpoise for the "top fed" or upside-down antenna.
Hope this gives some food
for thought. If anyone is interested I can tell of some real world tests I have done with this antenna but this has been a "wordy" post so I'll sign off for now...