"A LID operating QRO at an excellent northeastern US sea view site with excellent antennas -- is still only a *loud* LID, who is able to cause a lot more interference and consternation than a weak LID." The above is an excellent example of "confrontational interoperability," and close to the examples of "good" and "bad' interoperability I share with my students, Guy!!! 😊 72, Jim Rodenkirch K9JWV
> From: [email protected] > Date: Fri, 3 Apr 2015 15:59:39 -0400 > To: [email protected] > CC: [email protected] > Subject: Topband: Salt-Water Qth! > > On Wed, Apr 1, 2015 at 12:17 PM, <[email protected]> wrote: > > > > Its not practical to place a vertical closer than 1/4 > > wavelength of an ocean beachfront except in a temporary installation > > such as a DXpedition. > > Also [email protected] wrote: > > >>... "Is there any scientific data in print to prove the theory that ocean > front property is better than a location inland about a mile or so on a > ridge overlooking salt water for HF. ... I understand the theory that > verticals literally in or on the water have a huge advantage."... > >> > > It is not a theory that there is a remarkable increase in MF transmission > when closely approaching saltwater waterline. It has been observed over at > least a half century by what must now be millions of observers, certainly > the vast majority not hams, observed at least since inexpensive > transistorized portable radios were available around 1960. > > The 1960 date sticks in my mind because of a story that circulates among > Berea College alumni to this day about transistor radios scattered among > 1200 students stuck in a terribly boring required general assembly lecture. > Some 15 or 20 of these new all-the-rage radios were scattered all over the > assembly hall, and were tuned in to the 7th game of the 1960 world series > between Pittsburgh and the Yankees. Back then there were no earbuds to go > stealth. Volumes were low, but loud enough to hear without the giveaway of > the radio resting upon the ear. The winning run in the bottom of the ninth > resulted in barely suppressed cheers and moans and the cumulative uproar of > whispers mercifully brought the lecturer to a bewildered halt. We received > an outraged dressing down from the college president who, to his credit, > was the first up on the stage to figure out what was going on, and who > apparently was not a baseball fan. I won't get into why I know it was > terribly boring. But I digress... > > These and millions of others took these radios everywhere with them, and it > was soon common knowledge that you could hear the New York AM stations all > day long if you took the radio out over the salt water at east coast ocean > beaches as far south as Cape Hatteras. Not a bit of theory involved, just > undeniable observation. > > The wow factor of this has severely diminished since the internet, and > nobody except hams thinks that hearing NYC AM stations during the day down > the east coast is the least interesting. The question now is why can't the > complainer text high definition video to anywhere in the world over the > internet in five seconds or less. But transistor radios were really neat > new affordable stuff in 1960. > > The depth of the drop off walking away from the beach, the inverse of the > improvement walking toward it, exposes the answer to your question. > Whatever the theory, the fact remains of an often reported sharp change in > signals across several hundred meters, sometimes in significantly less > distance. > > The "mysteries" of near-to-ocean propagation or losses become less foggy if > one always carefully considers ground media loss in discussions. Ground > losses continue to be the "undiscovered country" of top band transmitting > antenna discussions, remarkably ignored in many discussions about 160 meter > antennas that require a counterpoise. These ignored counterpoise issues can > take back expensive amplifier gain with losses as large. > > Models depend on a monolithic uniform ground all the way to and beyond the > horizon and uniform to deep depth. Models need this to simplify computer > computations so they can run on ordinary PC's in times that are measured in > minutes rather than months or years. Accurate 160m modeling of what goes on > from 100 meters out in the water, across a sandy beach to 10 kilometers > inland cannot be accomplished with available resources and program code. > Some investigators have set up carefully at a site with antenna and serious > commercial measuring equipment, and have simply been unable to get > measurements to match a model, regardless of the ground characteristics > specified in the model. > > At the water line, the remaining difficulty at this point would be support > of a vertical. An FCP above and parallel to the water line or out over the > water would be a very efficient counterpoise and quite easy to erect with > inexpensive materials. A shortened aluminum vertical with large gauge > appropriately located loading coils could do very well in the short term. > It would have a narrow bandwidth, not being weighed down and broadbanded by > ground losses invoked by the antenna and the counterpoise. But the reality > of salt spray, wind, etc easily renders temporary anything other than a > tower and guys on piers ala the San Francisco station mentioned earlier. > And even that would require ongoing maintenance. > > The sea view cliffside location, with steps taken to minimize losses > directly underneath the antenna, seems best all band all around. Some argue > there is a surface wave phenomenon right over the water, demonstrated gone > after a few hundred meters inland. Such an actual propagation mechanism > will not be had at cliffside, however excellent the site otherwise. > > Perhaps someone who actually owns beachfront, including the sand or rocks > down to the salt water, lacking contrary legislation, will be able to put > up something measurable right over the salt water and and keep it up and > efficient long enough to report results. > > And even if a cliffside sea view location was worth an S unit or two, > nothing overmatches the dB between the ears. A LID operating QRO at an > excellent northeastern US sea view site with excellent antennas -- is still > only a *loud* LID, who is able to cause a lot more interference and > consternation than a weak LID. > > 73, Guy > _________________ > Topband Reflector Archives - http://www.contesting.com/_topband _________________ Topband Reflector Archives - http://www.contesting.com/_topband
