The South Carolina ‘FM Tropo Wall’ (updated)

South Carolina's state flag.
South Carolina’s state flag.

UPDATE 10/15/13: I received my second South Carolina FM signal, 92.9 WEGX Dillon, SC @ 318 miles, on 10/15/13, proving that FM signals can pass through the SC/NC state line.  The original article as posted on Aug. 19, without mention of this new logging, is below.

I wait and wait every time strong tropo extends deep into North Carolina. Will it happen?  Will I finally get South Carolina on FM?

Time and time again, the answer is always a resounding ‘no.’

In 14 years of DXing, I have only logged one FM station from SC via tropo, even when tropo is strong into NC markets just minutes north of the border.

The NC/SC state line is 298-339 miles away from my Northern Virginia home, depending on location.  The only SC FM logged, 103.3 WJMX Cheraw, SC @ 323 miles, was received on 8/4/99 with a chorus of eastern NC FM stations coming in within the 200-300 mile range.  Although I’ve had the same regional stations dozens of times in the past 14 years (often with stronger reception than 8/4/99), nothing else has been logged south of proverbial “SC tropo wall.”

I’ve noticed that almost all tropo openings in my area favor the south, with endpoints typically maxing out in the coastal areas of Outer Banks, or Wilmington at distances between 250-320 miles.  Inland tropo into Raleigh, Charlotte, Winston-Salem and Greensboro at the same distances are common, just not as much as coastal tropo.  About 1-2 times biannually, I’ll get a tropo duct toward the northeast, with signals from PA, NY, CT, RI and MA common with distances maxing out at 420 miles—ironic since I almost never get tropo signals in that direction past Philadelphia, which is 142 miles away.

Click to enlarge.
Click to enlarge.

A common foe of DXing, mileage, doesn’t seem to be the culprit here.  The picture at the right shows three stations 14-30 miles from the NC/SC border in North Carolina that I’ve logged .  95.1 WNKS is 307 miles away, while WFLB and WGNI are 286 and 322 miles away, respectively.  WGNI, at roughly the same distance as WJMX, has been received dozens of times, often with stereo reception, in the past while WJMX was only received once.  At 420 miles away, 99.9 WQRC Barnstable, MA was received twice during northeastern tropo since 2005.  I find it ironic that WQRC (as well as other stations in the 300-400 mile range) can be received to the northeast—a rare path—while I don’t see the same distances to the south, where tropo is more common and often much stronger with a larger selection of DX signals received.

A frustrating fact is that a market I’d really like to receive on FM—Myrtle Beach, SC—is only 47 miles south of Wilmington just across the border and it *should* come in weakly when the tropo is coming in from that direction.  But, of course, I’ve never logged a Myrtle Beach FM at home.  I actually DXed FM radio while in Myrtle Beach in 2012, and northward tropo from North Carolina (with signals from Raleigh, Outer Banks, etc.) was heard during the day, so it is obvious that the NC/SC state line doesn’t have some sort of physical RF ‘wall,’ as it may seem from my Virginia home.  If NC signals can easily drift into SC, why can’t SC easily drift across NC into VA?  To add salt to the wound, 530-mile FM tropo while in Myrtle Beach (to the south into Florida) was easily achieved with the simple indoor wire antenna that was supplied with the Sony XDR-F1HD radio.

Ironically, DXers in the northeast (those living in PA, MA, CT, etc.) frequently report logging SC FMs on the TV/FM Skip Log, with distances upward to 650 miles away, if not more.  At the same time, instead of getting stations 650 miles away in Georgia or Florida, I’m only getting stations north of the NC/SC state line.  The ducts that end in SC always, somehow, miss me by about 120 miles, favoring much-further areas against the typical ‘laws of propagation’ for FM signals.

I’ve almost given up trying to figure out what may be at fault here.  If WGNI is an easy catch, why can’t signals 47 miles further away in SC be picked up at the same time?  The majority of Myrtle Beach FM signals are almost all on non-local frequencies, so interference or exclusion from locals on the same frequencies (as is the problem with receiving most Philadelphia and New York, NY FM signals) can’t be an explanation to this mystery.

Then I wonder if living at the bottom of a steep hill may be just enough to curtail SC FMs from coming in, however that hill is to the west while SC is to the S and SW and (again), I’ve received FM tropo within 14 miles from the NC/SC state line.  So, that can’t be it, either!

Click to enlarge.
Click to enlarge.

Perhaps the signal paths of SC to VA is the culprit.  The east coast takes a southwestward ‘dip’ just north of SC.  For most SC FMs to be received, they have to be picked up by a land-based tropo duct that goes through inland North Carolina—a path that is less-favored instead for ocean-enhanced signals from the NC eastern coast.

So this could be what is happening:  weak SC signals from the lesser-favored path may make it into Virginia, however much-stronger and closer signals from eastern NC (often on the same frequency) may make it to my radio just a tad bit stronger to allow my radios to receive them instead of SC.

For example, a prime SC target is 92.9 WEGX Dillon, SC at 318 miles, 100kw, just south of the NC/SC border close to already-logged WJMX.  During every tropo opening, 92.9 FM is always WVBW Suffolk, VA @ 132 miles, 50kw.  WVBW always comes in as a local, with full RDS decodes when eastern NC tropo is present, but weak when tropo is into the northeastern states.  If there was a way I could null WVBW’s blowtorch signal, maybe WEGX would pop in.  Another example: 97.7 FM is home of a semi-local, WMDM Lexington Park, MD @ 46 miles, however it is usually overpowered by 97.7 WGTI Winfall, NC @ 171 miles or (to the north) 97.7 WAFL Milford, DE @ 97 miles during good Tr openings.  So, why couldn’t Myrtle Beach’s 97.7 WWXM Garden CIty, SC, with a mammoth 100kw signal, never make it up to Northern Virginia when nearby WGNI is blaring in?

The lack of FM stations past a pretty obvious barrier, especially in the picture above with WNKS, WFLB and WGNI where the furthest signals received in that direction seem to mimic the NC/SC line, is very strange.  My northern FM records into MA, CT, RI, etc. seem to be distance-related and not tied to a specific state line or any other man-made map barrier.  There are no physical restraints, such as mountains, at the NC/SC line which would make a sudden ‘drop-off’ in terms of signals received to be understandable.

Water enhancement isn’t the answer either, I suspect.  Although tropo ducts bringing in the northeast states’ FMs into Virginia pass the coastline and the ocean several places, it also goes over a large swath of land in NJ, DE and MD.  Plus, the aforementioned DXers in PA, NJ, etc. who do get South Carolina on FM are more or less the same distance from the Atlantic Ocean as I am, so I would suspect the likely 500+ mile enhancement DXers on the Atlantic shore gets when I’m getting eastern NC on FM doesn’t go too far inland.

As DXing is a hobby where ‘expect the unexpected’ is a common occurrence, maybe one day I’ll turn my radio on to a band full of SC FM and TV signals.  One can hope…