DIRECTIONAL PATTERNS

[mobley]

I don't know if this has been discussed in the past, but I've found this to be fascinating aspect of radio (AM in general)

A few things of note:

WBT Charlotte blasts into Maine and Florida at night, but can't be heard in Gastonia, 23 miles away.

Legend has it that WAPE AM (now WOKV) could not be heard on air at their night time X-mitter site.

Some stations seem to drop off instantlly, while others fade slowly as you get out of the pattern. I've also heard a strange effect that sounds like skywave fade. WINS in NY would do this a lot in the daytime in Morris Co. NJ. You could turn a corner with the station fading and drive a few yards and it would pop backi in. Same with WHP in Harrisburg along I-81 at night. There's one area where it sounds like a splattering signal, then suddenly comes back in for a few miles.

Coming back from Chraleston SC I punched in 690 from Jax at about 5:55AM. There was basically mothing but several signals fighting. All of a sudden WOKV appears as if you were under the towers.

Anyone know of any unique patterns or other signal anomolies, due to directional patterns?

 

[radioman148]

I don't know if this has been discussed in the past, but I've found this to be fascinating aspect of radio (AM in general)

A few things of note:

WBT Charlotte blasts into Maine and Florida at night, but can't be heard in Gastonia, 23 miles away.

Legend has it that WAPE AM (now WOKV) could not be heard on air at their night time X-mitter site.

Some stations seem to drop off instantlly, while others fade slowly as you get out of the pattern. I've also heard a strange effect that sounds like skywave fade. WINS in NY would do this a lot in the daytime in Morris Co. NJ. You could turn a corner with the station fading and drive a few yards and it would pop backi in. Same with WHP in Harrisburg along I-81 at night. There's one area where it sounds like a splattering signal, then suddenly comes back in for a few miles.

Coming back from Chraleston SC I punched in 690 from Jax at about 5:55AM. There was basically mothing but several signals fighting. All of a sudden WOKV appears as if you were under the towers.

Anyone know of any unique patterns or other signal anomolies, due to directional patterns?

The two that stand out in my mind is AM 1000 in Chicago and 1110 in Pasadena, Ca.
If you drive west of Aurora, Il, AM 1000's signal takes a huge drop. When 1110 in Pasadena was KRLA I could listen to it driving east to about San Bernardino and then it was toast--especially at night.

 

[BRNout]

Well, there are tons of examples available to cite. A couple that I have good experience with are WRKO Boston, a 50 kw station at 680 kHz. At night, they go directional toward the east from their transmitter site in Burlington, MA (15 miles NW of downtown Boston). But they stay with 50 kw.

If you're in a western or northwestern Boston suburb, their signal strength falls off the table and into the mush as soon as they make the switch. And, if you're driving southbound along I-495, you experience a strong signal near Lowell and Chelmsford, MA and basically no signal at all in Littleton and Bolton (within 10 miles southwest). Station comes in much better at night (via groundwave) in Maine than it does in suburbs that are only 15 or so miles from its tx site. Frankly, I could have also cited Boston's WWZN and WEEI too - but WRKO seems the most obvious because they have (by far) the best groundwave signal of the 3.

By the way, the maps of this one on Radio-Locator are far too generous to the west. The cutoff is much sharper. I had trouble picking them up in the car in areas that are within the 'purple line' and even heard stations from Toronto and Binghamton coming in more loudly at times. It would be like WLS not being able to serve Will, McHenry. Kane and the western two-thirds of DuPage County at night.

WISN Milwaukee is another station where the switch to a nighttime directional signal basically shuts it off to the nulled area. Locally, in Chicago's northern suburbs (roughly 65 air miles from their tx), the station goes from a 6/10 signal strength to around zero. It must really blast into upper Michigan and Ontario because it's 10 kw nighttime signal is just dead to the south. Very stark change at sunset. Again, Radio-Locator is too generous within the station's null; I basically lost it in the car driving through Gurnee when they did the antenna switch at local sunset. It was as if they shut down the tx.

 

[dave73]

WISN Milwaukee is another station where the switch to a nighttime directional signal basically shuts it off to the nulled area. Locally, in Chicago's northern suburbs (roughly 65 air miles from their tx), the station goes from a 6/10 signal strength to around zero. It must really blast into upper Michigan and Ontario because it's 10 kw nighttime signal is just dead to the south. Very stark change at sunset. Again, Radio-Locator is too generous within the station's null; I basically lost it in the car driving through Gurnee when they did the antenna switch at local sunset. It was as if they shut down the tx.

The reason WISN must have a sharp null to the south, is to protect KWKH Shreveport, Louisiana, plus a big null to the east to protect WBBR New York City, which are both Class A (formerly Class 1-B) stations. They do have to protect next nearest co-channel, WDFN Detroit, which is actually closer to Milwaukee than New York, but still must protect the New York station. WISN must also protect KFAN Minneapolis, which I've picked up in Gary Indiana at night, when I didn't get WKWH. That's why the signal mainly goes north at night, and very narrow.
I've traveled along I-94 on my way to Milwaukee, and I know that WISN is barely heard in Kenosha County, due to splatter from WKKH, KFAN, and WDFN. I wouldn't even get WISN until I got near Racine County.

 

[gar hi]

WWMI 1380 from St. Pete is a good example. During the day, they are non directional 5kw. When they switch to their directional signal at night that aims the entire signal SW out in the Gulf, it can hardly be heard at all in the NE parts of Tampa. Like others have said about other such stations, the Radio Locator map seems to show it as being stronger in that location than it really is. The ironic thing is, I once picked up 1380 up in New Jersey back in the late 80s when they were WRBQ AM Stereo playing top 40. It was just around sunset and they probably hadn't yet switched to their nightime pattern.

 

[drt]

WWMI 1380 from St. Pete is a good example. During the day, they are non directional 5kw. When they switch to their directional signal at night that aims the entire signal SW out in the Gulf, it can hardly be heard at all in the NE parts of Tampa. Like others have said about other such stations, the Radio Locator map seems to show it as being stronger in that location than it really is. The ironic thing is, I once picked up 1380 up in New Jersey back in the late 80s when they were WRBQ AM Stereo playing top 40. It was just around sunset and they probably hadn't yet switched to their nightime pattern.

WTSP/WLCY/WNSI/WRBQ/WWMI (there, I think I have all their call letter changes! ) was a station that came to my mind as well.

Just as you mentioned, WWMI 1380 is almost non-existant at night in north Tampa; basically, if you're north of Waters Ave and west of I-275, you're not going to get much of a signal out of 1380 at night; the same is true for parts of
Clearwater, if you're west of Hercules
Ave (Clearwater High School) at night, it as though there is no station on 1380; not a local one anyway as you get closer to downtown Clearwater and Clearwater Beach, it's even worse.

Interestingly enough, I have read where 1380 was either the first or one of the first radio stations to employ a directional pattern. (depends on what source you read as to whether they were the first or one of the first).

Where I am, (near the Bayboro Campus of USF) the signal is actually stronger at night and it's stronger at night in Palmetto and Bradenton as well; especially west of U.S. Hwy 41 (14th W in Bradenton, Tamiami Trail further south). 620 also puts out a stronger signal at night where I am; if you're in Florida and on the north end of a city, the odds are your nighttime A.M. reception is not going to be as good as daytime, since every Florida station I can think of that has a directional pattern nulls to the north, nne, nnw, northwest or northeast at night; very few null to the east or west and those that do (WFLF 540 for example) also null toward the north.

drt

 

[radioman148]

Well, there are tons of examples available to cite. A couple that I have good experience with are WRKO Boston, a 50 kw station at 680 kHz. At night, they go directional toward the east from their transmitter site in Burlington, MA (15 miles NW of downtown Boston). But they stay with 50 kw.

If you're in a western or northwestern Boston suburb, their signal strength falls off the table and into the mush as soon as they make the switch. And, if you're driving southbound along I-495, you experience a strong signal near Lowell and Chelmsford, MA and basically no signal at all in Littleton and Bolton (within 10 miles southwest). Station comes in much better at night (via groundwave) in Maine than it does in suburbs that are only 15 or so miles from its tx site. Frankly, I could have also cited Boston's WWZN and WEEI too - but WRKO seems the most obvious because they have (by far) the best groundwave signal of the 3.

By the way, the maps of this one on Radio-Locator are far too generous to the west. The cutoff is much sharper. I had trouble picking them up in the car in areas that are within the 'purple line' and even heard stations from Toronto and Binghamton coming in more loudly at times. It would be like WLS not being able to serve Will, McHenry. Kane and the western two-thirds of DuPage County at night.

WISN Milwaukee is another station where the switch to a nighttime directional signal basically shuts it off to the nulled area. Locally, in Chicago's northern suburbs (roughly 65 air miles from their tx), the station goes from a 6/10 signal strength to around zero. It must really blast into upper Michigan and Ontario because it's 10 kw nighttime signal is just dead to the south. Very stark change at sunset. Again, Radio-Locator is too generous within the station's null; I basically lost it in the car driving through Gurnee when they did the antenna switch at local sunset. It was as if they shut down the tx.

WISN is a great example. I also live in the northern Chicago suburbs and WISN's good signal during the day is non existent at night. In fact I hear WBBR usually at night & I'm in their null.

 

[gar hi]

620 also puts out a stronger signal at night where I am; if you're in Florida and on the north end of a city, the odds are your nighttime A.M. reception is not going to be as good as daytime, since every Florida station I can think of that has a directional pattern nulls to the north, nne, nnw, northwest or northeast at night; very few null to the east or west and those that do (WFLF 540 for example) also null toward the north.

drt

Even way back in the day in the 70s when I hadn't a clue as to the exact directional patterns of the Florida stations, I discovered what is well known, that Florida is not a very good place to DX to. Up in New Jersey, the only Florida AM stations I ever got was that one time with the above mentioned WRBQ, the old 690 WAPE at the critical time when they hadn't switched to nighttime mode, and once down at the shore around sunset, I got the then 790 WFUN. Now that being said, Florida is probably one of the very best places to DX from.

 

[schmave]

The most severe nulls I can think of come from Columbus, Ohio, where I lived most of my life before coming to Houston:
- You can drive north to south a mile or so east of 610 WTVN's six-tower farm and hear yourself going in and out of the pattern; there is an extremely noticeable drop in signal even that close. Get five miles southeast and there is some fading.
Get 10 miles directly east of the tower and you lose 610 completely for about a mile. This is its eastern null to protect WIP in Philadelphia.
- Also in Columbus, 820 WOSU switches tower sites and drops from 5,000 to less than 1,000 watts at Dallas sunset to protect WBAP. By pure luck, I found myself about three miles from the tower directly in the deepest part of the null one night about two years ago just because the pattern switch, so I stopped and listened. The switch was amazing; it went from crystal clear to extremely weak in the mush within three seconds. It was not so deep as to be able to hear WBAP, but it was admirable nonetheless.
I have heard WBAP very strong within 10 miles of the WOSU transmitter before there's any hint of the two signals butting heads.
- Here in Houston where I now live, the nighttime null of KILT-AM (610) is darn impressive. It broadcasts from a four-tower inline array 15 miles north of downtown along I-45. You can drive down 45 from the northern suburbs after dark and get nothing on 610 to within 10 miles of the tower. There is considerable distortion until you get within two miles.
I went geeky the other day (before the flip to night pattern) driving north of the towers, then down 45 right next to them, and listened to the slop on 620 on my car radio to judge the signal. Even on the ramp looking straight at the towers, there was a considerable decrease in slop before I got to the east of the site and it was overloading onto 630 and even 640.

 

[EastBay]

Yo, where's all the west-coasters??

KGO is a full-time 50kw blowtorch, but the pattern is distinctly north/south. I pick it up just fine from San Diego to Seattle, but can barely hear it (if at all) in Reno.

 

[radioman148]

>>Now that being said, Florida is probably one of the very best places to DX from.>>

But don't the Cuban stations cause tremendous interference to your DXing efforts?

 

[radioman148]

Yo, where's all the west-coasters??

KGO is a full-time 50kw blowtorch, but the pattern is distinctly north/south. I pick it up just fine from San Diego to Seattle, but can barely hear it (if at all) in Reno.

KGO is a gigantic up and down the coast. In fact years ago I picked it up in southern Mexico.
But as you said in Reno you can just about forget it.

 

[radioman148]

Another weird one is 1160 in Chicago. When they transmitted day & night from Des Plaines you couldn't hear them at all at night 8 miles north of their towers. Now they're transmitting at night from a new site that is southwest of Chicago and beams northward--the direct opposite of their previous pattern.

 

[mimo]

A favourite of mine as far as directional patterns go is KCPS 1150 in Burlingtong Iowa. It's a 500 watt station that sends their signal straight south and east. North and west have absolutely nothing. When you aproach Burlington from the west on highway 34, you approach a little village called Middletown. It's 4 miles west of Burlington. Highway 34 enters Middletown from the north and makes a sharp turn to the left. The second you make that turn, the signal from 1150 goes from nonexistant to Perfectly local. At night it's more pronounceable. In the day it goes for another 7 miles west of Middletown on Highway 34. That turn on the highway still sharply decreases/increases the strength of the station, depending which way you're going.

 

[radioman148]

Another strange one was KOMA in Oklahoma City. Years ago when I spent some time down there I was about 10 miles south of their transmitter.
At night when they went directional you really had to turn the volume up to hear them. Seems weird because they were a 50KW powerhouse if you were north or northwest of OKC. They could be heard easily in Canada and in the pacific in those days but not 10 miles south of their towers.

 

[ddsparxx]

One station I know of is WBAL 1090 in Baltimore, MD, nondirectional at day and turning directional toward north, east and southeast at night. I can barely hear it at night in northern VA especially west of DC.

KPNW 1120 in Eugene, OR has a similar directional pattern, both day and night, mostly north-south and sharp null toward east to probably to protect KMOX 1120 in St. Louis and maybe KBND 1110 in Bend, OR.

 

[BobOnTheJob]

The most severe nulls I can think of come from Columbus, Ohio, where I lived most of my life before coming to Houston:
- You can drive north to south a mile or so east of 610 WTVN's six-tower farm and hear yourself going in and out of the pattern; there is an extremely noticeable drop in signal even that close. Get five miles southeast and there is some fading.
Get 10 miles directly east of the tower and you lose 610 completely for about a mile.

WTVN's null to the west to protect Kansas City is amazing. In central Indiana, WTVN provides a very listenable daytime signal. As soon as they switch pattern, it is GONE...even if there is nothing but noise to replace it. It's obvious that their Directional antenna is very well maintained, unlike some. There's one call sign mentioned in this thread that, when it worked properly 20 years ago, was gone 3 miles west of the towers, even though you could see the towers almost to the ground. Now you can hear it 20 miles into the null at night. And the amazing thing is that the FCC fined that station for a fencing issue, but totally overlooked the fact that the directional pattern had been out of whack for a decade or more at the time. You just don't read much about fines being levied for improper directional operation. And yes, that contributes to the decline of the AM band.

 

[gar hi]

But don't the Cuban stations cause tremendous interference to your DXing efforts?

On some frequencies, yes, but not all and even on the ones it does it varies and will get pushed in the background in favor of the northern stations depending on the conditions.

BTW, although I didn't get any ID, I'm almost certain I heard KFI again last night. It was around 1:15 am and instead of hearing the usual slop, I heard a fairly decent signal pop up for less than a minute and it was the Coast to Coast show. The signal was the best facing the radio WNW. I listened for about 45 min. after that but all I got was the Cuban and that old time station from here in Florida.

 

[w9wi]

Interestingly enough, I have read where 1380 was either the first or one of the first radio stations to employ a directional pattern. (depends on what source you read as to whether they were the first or one of the first).

620 was the first directional antenna, to protect a co-channel station in Milwaukee.

WTSP, the station that would end up on 1380, launched on 1370 - a "graveyard" frequency where directional antennas were not used.

 

[radioman148]

One station I know of is WBAL 1090 in Baltimore, MD, nondirectional at day and turning directional toward north, east and southeast at night. I can barely hear it at night in northern VA especially west of DC.

KPNW 1120 in Eugene, OR has a similar directional pattern, both day and night, mostly north-south and sharp null toward east to probably to protect KMOX 1120 in St. Louis and maybe KBND 1110 in Bend, OR.

KPNW sends alot of signal into the pacific. It can be heard at night in Hawaii.