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Re: Topband: Modeling the proverbial "vertical on a beach"

To: topband@contesting.com
Subject: Re: Topband: Modeling the proverbial "vertical on a beach"
From: Mark Connelly via Topband <topband@contesting.com>
Reply-to: Mark Connelly <markwa1ion@aol.com>
Date: Sat, 16 Aug 2014 22:45:30 -0400 (EDT)
List-post: <topband@contesting.com">mailto:topband@contesting.com>
Some long-time observations from about 55 years of AM broadcast band DXing MAY have some relevance to this discussion.

That hobby has had a lot of simultaneous inland-versus-coastal signal strength comparison studies over the years, largely from the US and Canadian Atlantic and Pacific coasts but also from a variety of other sites around the globe.

Nick Hall-Patch (VE7DXR) and Chuck Hutton (WD4ELO) who comment periodically on this list are both active in both amateur radio and broadcast DXing. They, along with Bruce Portzer, Guy Atkins, Gary DeBock, Pat Martin, Walter Salmaniw, Dallas Lankford, and others have done a lot of DXing at prime sites along the Oregon, Washington, and British Columbia coast.

Here on the East Coast, many observations have been done by enthusiasts such as Bruce Conti, Neil Kazaross, Ben Dangerfield, Jean Burnell, Marc DeLorenzo, and myself. Both simultaneous listening at various sites and long-term observations from somewhat-inland and "beach DXpedition" sites have given rise to a number of findings. There could be at least a certain amount of crossover relevance to 160m and perhaps even 80/75m.

Here are a few conclusions:

* The advantages of being at the shore are substantial in the pre-sunset period along east-facing shorelines and post-sunrise along west-facing shorelines. Saudi Arabia 1521 (2 megawatts) can be heard up to 4 hours pre-sunset in autumn / winter right at the shore in New England and Atlantic Canada, even with modest antennas. At sites even just 10 miles (16 km) inland, two hours pre-sunset is about as good as you get on similar "compromise" antennas. Here's a typical Massachusetts coast recording of the 1521 flamethrower: " http://www.qsl.net/wa1ion/audio1/dx_saudi_arabia-1521_20060503_2300z.mp3 ". A small car roof mounted loop was all that was necessary.

* The differences between shore and inland are less when efficient full-sized antennas (vertical at least 1/8 wave over a good radial system, or halfwave dipole mounted a quarter wave or higher above the ground directly below it) as contrasted with lower-efficiency / smaller antennas often used for receive (figure-of-8 or cardioid-pickup loops, active whips), especially if those antennas are near the ground. No surprise there.

* The differences between shore and inland are less when the route is shorter, the path is all dark, and solar activity is low. New England to UK or Norway in autumn or winter might only show about a 6 dB advantage to a coastal site to a similarly-equipped station inland (meaning, roughly, more than 20 miles of average soil to the nearest salt water on the bearing of interest). Deep Africans and South Americans heard during auroral conditions, or anything from the Middle East and beyond (> 5000 miles) at any time, will show a strong enhancement, at least on smaller antennas, near the shore. For many years I have been noting what medium wave stations from places such as South Africa, Lesotho, Brazil, and Argentina can do at various sites in Massachusetts. Up to 2012 I lived in west-suburban locations near Boston. These are more than 30 miles from the ocean on the southeasterly bearings towards Brazil. In thousands of hours of listening over more than 50 years I think that four or five Brazilians would be the maximum logged in the 530-1710 kHz range. Where I am now in South Yarmouth, MA on Cape Cod - about two miles from West Dennis Beach on the range of Brazil-ward bearings - I've logged close to 10 Brazilians in about two years. My parents' house in West Yarmouth (1974-2001) and my brother-in-law's in East Harwich (1994-2004), also about two miles inland on Brazil bearings, performed similarly to my present QTH. But the big winner is listening from the car directly sited at beaches with open water to the southeast. I had more than a dozen Brazilian stations in a single two-hour session at Orleans, MA and, cumulatively, over 20 stations from Brazil in the logbook as a result of various MA beach DXpeditions over the years just using small loop or active whip antennas mounted on the car roof - antennas far inferior to what could be run at various house-based sites. The station from Fortaleza, Brazil on 760 kHz barely ever registers a peep in the suburbs west of Boston but it's often loud around sunset (after semi-local WVNE power-down) at shore locations such as Tonset Rd. - Orleans, MA (Cape Cod) and Granite Pier - Rockport, MA (Cape Ann). The shore-vs.-inland difference on that one is easily 25 dB. This is why, on both coasts of North America, year after year, broadcast-band DXpeditions produce loggings in a single night that the same DXers have not heard from home in a lifetime of listening, sometimes even if using better receivers and antennas. So many years of different DXers noting the same results take a lot of the statistical uncertainty out of the equation - it just can't be that every time someone went out to the shore the propagation magically went crazy and then went back to dull / normal as soon the DXer was back in his own driveway. Anyway, that significant shore-versus-inland conditions can exist is borne out by the fact that, on at least some occasions, several DXers were listening at the same time from various sites and noting big differences in strengths and quantity of long-haul loggings. It used to be difficult to prove things when you had to be on the exact same frequency at the exact same time. Nowadays DXers are saving the entire spectrum to disk from SDR receivers such as Perseus and Excalibur. A top-of-hour (prime ID time) +/- 2 minutes band capture from Location A can now very accurately be compared to one made during the same time interval from Location B.

* There are times that, contrary to common intuition, a very long haul route is best covered by antenna that works for high take-off angles. This is typically during greyline transitions and results from reflective-layer tilting / chordal-mode propagation. During such a condition, my "gut feel" is that there should be very little difference between coastal and inland sites.

* To muddy things up further, inland sites can vary quite a bit too. Some of the advantage of shore sites may be owing to minimal obstructions as well as to good conductivity. Obstructions degrade lower-angle signals as well as poor ground conductivity. An inland "wide open farm" (or grassy marsh area) with a long view to the horizon in the direction of interest is going to outperform a "typical suburban" site with buildings, power lines, and tall trees towards the DX. An elevated site would outperform normal suburbia for the same reason. Just as with a shore site, the unobstructed-view inland site is also apt to have less man-made RF / local electrical noise coming in from the desired direction than "average" sites in developed areas.

* If you don't have a coastal site, altitude would be the next-best magic bullet. This means both in terms of the antenna height above the ground directly below it and the actual surface level relative to surrounding terrain. A house site that I used in East Harwich, MA was about a mile and a half inland over lossy sandy soil. Sunset-period transatlantic reception on a small homebrew broadband loop of similar performance to a Wellbrook ALA1530 was evaluated at a nearby shore site (Town Landing near Tar Kiln Road - S. Orleans, MA) and at the house. Predictably, big stations such as Algeria 549 and Saudi Arabia 1521 came in an hour earlier right at the seashore. Some of the inland deficiency was removed by relocating the small loop from near-ground-level to about 70 ft. height (via rope over the top of a pitch pine tree). I'd say that the treetop loop performance came in about halfway between the near-the-ground loop operated at the house and operated at the shore.

The latest crazy aspect of medium-wave DXpeditioning is exploiting TWO magic bullets - seaside PLUS altitude - at the same time. Gary DeBock (N7EKX) has led the charge on this at the "Rockwork 4" site on the Oregon coast. See " http://www.antenadx.com.br/?wpdmact=process&did=MjcxLmhvdGxpbms= " for one write-up. From 2013 we have a DXpedition article starting with "Concurrent with a separate DXpedition in Yachats (OR), from July 21-27 another wild ocean cliff DXpedition was conducted from "Rockwork 4," a 400' high sheer cliff located on Highway 101 in Tillamook County, Oregon." See " http://www.hard-core-dx.com/article.php?story=20130731111543372&mode=print ".

Sample reception of 603 kHz Radio Waatea in Auckland, New Zealand, 5 kW:
" http://www.mediafire.com/listen/u25glqbzfr7e2h3/603-R.Waatea-1253z072213PL380.MP3 ". No one in the USA has heard a signal like that from this station at inland home sites.

Acadia National Park in Maine has similar sites with both salt water proximity and high altitude. Strong Brazilians on 1100, 1220, 1280, etc. are pretty common stuff at the top of Cadillac Mountain there.

As others have mentioned, you can undo a lot of the "inland disadvantage" by the use of highly-efficient tall verticals over a copious radial field or a horizontal antenna at heights in the half-wavelength or greater range, e.g. 250 ft. at Topband. Site altitude (mountaintop) or, barring that, wide open level or downsloping farmland free of obstructions will help too.

Sometimes it's all up to the ionosphere. Of US regions, New England often has the best punch to Europe if only because of shortest distance - coastal vs. inland notwithstanding. But if the auroral "doughnut" (torus) is too much in the way, Florida will outperform by using open paths south of the auroral zone. Northern Lakes and Plains states (e.g. Minnesota) might also outdo W1-land by getting through the "doughnut hole." Certainly going US to northern Norway and Sweden this is often the case: the route from MN, ND, etc. over Hudson Bay can frequently beat what's coming from MA, NY, etc. along the Atlantic but heading straight into the jaws of the aurora.

Now that we've analyzed the heck out of shore versus inland, I guess mountaintop versus lowland would be the next thing to discuss.

Mark Connelly, WA1ION
South Yarmouth, MA


<<
Hi Guys


K3ZM is my brother - and his 160m antenna is located in a salt marsh just to the West of Chesapeake Bay in Matthews, Va as I recall. Indeed he is located inland a bit (eg: not directly at water's edge) - perhaps 1000 feet distant (although this is only a guess on my part from photos I have seen). But the intervening land is also primarily salt marsh. At certain times of the year this land floods with salt water and it is necessary to wear very tall boots in order to walk out to the base of the towers Peter owns. I am sure Peter could add more
specifics.


From conversations I have had with Peter over the years - and from listening to his signal over at 7O6T, I can tell you that he is very competitive when compared to his peers. Additionally, his ability to hear for a location so far South (eg - not in New England) - especially in winter is quite remarkable His
contest results in 160M contests speak for themselves.


Other observations - perhaps relevant, perhaps not.


W1WEF and I often get together for lunch in Orleans on Cape Cod. Jack works the HF bands from his mobile CW rig in his car - and when he drives out to the peninsula where I live (just off Pleasant bay which is salt water) - dead 15m and 20M bands magically go from NO European signals to a full band of signals as he comes up the road that runs along the Bay. He describes it as going from a DEAD BAND to a wide open band as he nears my home. This is in the daytime in
summer as I recall.


Personally here at VY2ZM - I am sure by co-locating my vertical systems at or near the water's edge has helped me - to what degree I am not sure - but it is
rare to be outheard looking NE or East on the lowbands.


During this thread I am pretty sure I read a post that co-location near Salt water is additive also for horizontal yagis. I do not believe this to be correct. My good friend Don Toman has several times told me the effect we are seeing here is primarily limited to verticals - and not to horizontal yagis - which according to Don, rely principally on their height above ground as the key
variable impacting their performance.


On the other hand, shooting out over open ocean from a slightly elevated position with HF yagis is a pretty good takeoff to be sure. Especially when compared to looking uphill over land in other directions - which I find causes
performance to suffer by comparison.


FWIW


Salt water is good stuff. Especially for verticals placed at or near the ocean - with additional ocean out in front of the antenna for hundreds of miles. I too have never fully understood the phenomena but I know it is magical in terms
of lowband DX'ing performance.


73 JEFF  K1ZM/VY2ZM

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