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Number of towers in a Directional Array

S

secondchoice

Just saw a thread about a KY station going from B to D to save the cost of maintaining a directional antenna farm. It got me thinking, which US stations has the most towers in its a directional array? The most I can recall is KNTH Houston TX with 11. I have heard a couple of contract engineers (in a bar so I am suspect) talk of some stations (WFLI) having "passive blockers". I never understood how just a grounded tower would have enough effect to warrant the cost of extra tower(s). Back in the day (pre 80 90), when you had to do manual readings, I bet writing down all of the current and phase readings could cause writers cramp on a 11 tower array.
 
KFXR-1190 Dallas (the old KLIF). 4 towers day in Irving, TX with 50KW, 12 towers night from Rockwall, TX, aimed due west with 5 KW to protect San Antonio Fort Wayne and Kansas City. The 12 tower site has only six towers lighted at night but back in the day when they were all blinking it looked pretty cool.
That site has been surrounded by subdivisions and I believe an elementary school and there are a couple of microwave and cell towers nearby directly in the main lobe.

Scott Fybush has a pic on his tower website, or go to FCCinfo.com, pull up the station and have a look for yourself with the map it feature.
 
It makes you wonder how many of these AM stations with massive tower fields will survive in the future. In the past 5 years or so, I know of 4 stations going dark because their tower field was sold out from under them, and these stations only had three or four towers.

If the housing market ever comes back, the combination of high property taxes, and/or developers that are will to pay enough for the property to buy an FM stick (or get the owner out of debt), will be the cause of extinction for a lot of AM's with shaky finances and a big tower field.
 
You are correct on maintenance...Check the cost of rebulbing and painting a 500' FT....if you are lucky you can come in for less than 4K....(Probably not)...JBI
 
KNTH in Houston has 9 500+ footers and 2 shorter sticks. KGOW in Houston has 6 towers at the day site and 9 towers at the night site. 15 total towers to maintain.
 
That has to be one of the most mutated looking night patterns I've ever seen.

12 towers, plus 4 more for the daytime. That's lots of transmission line...
 
I had the pleasure of visiting the KLIF 1190 Rockwall night site one evening in the late 70's. I was sitting in a friend's car in the middle of the array, where the null was so deep that we could actually receive WOAI 1200 in San Antonio from ~200 miles away within 50 feet of KLIF's reference tower - hearing only sideband splatter from 1190. Now THAT'S a tighty designed array for ya!
 
WLQV (1500) in Detroit has a very impressive antenna farm south of town. It's 50 kW days into 9 towers...and at night it runs 5 kW into a total of 12 towers. All the towers are about 250 ft. tall. They've gotten a CP to reduce to 9 towers 24/7 with a little looser pattern, and bump night power to 10 kW. Evidently they convinced the FCC that KSTP in Minneapolis/St. Paul and WFED in DC wouldn't be bothered by the change...

That isn't the only monster array in Motown. WDFN (1130 kHz, 50/10 kW, DA-2) uses only two towers for its day pattern. but a total of 9 at night arranged in a rectangle of three rows of 3 in each row.

WXYT-AM (1270 kHz, 50 kW, DA-2) uses 9 irregularly arranged towers each less than 200 feet tall for both patterns.

WCHB (1200 kHz, 50/15 kW, DA-2) only needs four towers for its day pattern but 10 towers (two parallel rows of five, oriented northeast to southwest) for nights.

WFDF (910 kHz, 50/25 kW, DA-2), the Radio Disney station, uses 8 towers in two irregular rows.

WWJ (950 kHz, 50 kW, DA-2) uses six towers, four 400 footers and a pair of 500 footers, both day and night.

Among major radio markets, all that metal may not make Detroit the directional antenna champ , but it has to be a contender...
 
Toronto has a bunch of multitier multitower arrays. Chicago is getting there.

Many of the new DAs in the Detroit area are unconventional designs. I think WFDF has just one tower out of line from a two parallelogram arrangement. WXYT, a few miles south of WFDF, has such an odd 9 tower arrangement that it is even difficult to model to understand. WWJ, a few miles east of WXYT, is a bowed parallelogram arrangement. The middle two towers are further apart than the end towers. The different heights tailor the vertical radiation pattern to protect some close in stations (200-300 miles away).

Many of the new 50 kW former Class IIIs are among the oldest stations in the country.
 
Bob1370 said:
WLQV (1500) in Detroit has a very impressive antenna farm south of town. It's 50 kW days into 9 towers...and at night it runs 5 kW into a total of 12 towers. All the towers are about 250 ft. tall. They've gotten a CP to reduce to 9 towers 24/7 with a little looser pattern, and bump night power to 10 kW. Evidently they convinced the FCC that KSTP in Minneapolis/St. Paul and WFED in DC wouldn't be bothered by the change...

That isn't the only monster array in Motown. WDFN (1130 kHz, 50/10 kW, DA-2) uses only two towers for its day pattern. but a total of 9 at night arranged in a rectangle of three rows of 3 in each row.

WXYT-AM (1270 kHz, 50 kW, DA-2) uses 9 irregularly arranged towers each less than 200 feet tall for both patterns.

WCHB (1200 kHz, 50/15 kW, DA-2) only needs four towers for its day pattern but 10 towers (two parallel rows of five, oriented northeast to southwest) for nights.

WFDF (910 kHz, 50/25 kW, DA-2), the Radio Disney station, uses 8 towers in two irregular rows.

WWJ (950 kHz, 50 kW, DA-2) uses six towers, four 400 footers and a pair of 500 footers, both day and night.

Among major radio markets, all that metal may not make Detroit the directional antenna champ , but it has to be a contender...
Click to expand...

WLQV has been down to 9 towers for a number of years now. They were allowed to eliminate 3. It's still an impressive array to see, but it was even more impressive when there were 12 towers in that field.

Didn't the old WDGY 1130 in Minneapolis also have a 12 tower array at one time? From what I remember, the transmitter plant was rebuilt, or maybe even replaced by a new plant at a different site, and now only has 9 towers.

While WCHB is now on 1200, it was at one time on 1440, where WDRJ is now. They also have a 12 tower array in a sense. It is actually two 6 tower arrays, one for day, one for night, but they are on the same piece of land.

Not far up the road to the north and across the border, CKTY 1110 in Sarnia, Ontario, also had a 12 tower array, but they closed down the AM and moved to FM in 1999.

I know the original posting was in reference to US stations, but two other Canadian stations are worth mentioning here because they both had 13 tower arrays, which were the largest I was aware of in North America.

CFGM 1320 licensed to Richmond Hill, Ontario, just north of Toronto, operated from a 13 tower array in Mississauga until it was granted a change of frequency in the 80s to 640. With that move, they built a new 8 tower array on the Niagara Peninsula, across Lake Ontario from Toronto.

CFTR 680 Toronto also operated a 13 tower array in Mississauga, just down the road a short distance from the CFGM site. That site was used when they were still operating with 25 KW. This site is especially worthy of mention because when CFTR originally sought to increase to 50 KW, engineering studies showed that they would have to add 4 towers, which would have made it a 17 tower array. In order to be able to increase to 50 KW, CFTR had already paid CHLO 680 St. Thomas to move to 1570, and CKGB 680 Timmins to move to 750. The remaining problem was a 250 watt daytimer on 680 to the east and across Lake Ontario in Rochester, New York. Although CFTR had offered many times to cover their expenses to move to another frequency, that station refused, which is why a 17 tower array would have been necessary to protect it with a 50 KW signal from Mississauga. As it turned out, CFTR built a new 8 tower array on the Niagara Peninsula, across Lake Ontario from Toronto, and somewhat ironically, just down the road to the west of the new CFGM 640 site. The new CFTR site was first used for 50 KW night only, with the 25 KW site in Mississauga still used for day. In time, CFTR increased daytime power to 50 KW from the new site. Meanwhile, interference in Rochester drove the little 680 station there to 990.

One interesting note about the new CFTR site is that they have two STL dishes, one at the top of one of the towers, and the other at roof level of the xmtr building. I asked about that when I visited the site. Because the STL signal shoots across the lake from Toronto, the difference in the water temperature sometimes causes the signal to bend to the point where it is lost, so they sometimes have to switch between the higher and lower dish at the xmtr site.
 
xrey said:
I had the pleasure of visiting the KLIF 1190 Rockwall night site one evening in the late 70's. I was sitting in a friend's car in the middle of the array, where the null was so deep that we could actually receive WOAI 1200 in San Antonio from ~200 miles away within 50 feet of KLIF's reference tower - hearing only sideband splatter from 1190. Now THAT'S a tighty designed array for ya!
Click to expand...

That would have been a good Kodak moment...

(And better than sitting in the middle of the 1480 array, too)
 
RadeoEngineer said:
The cost of tower maintenance alone is enough to kill some small operators.
Click to expand...

Or the cost of insurance and taxes on the big parcels of land....
 
There was a rumor that Consulting Engineer Harold Munn had a design for a twenty one tower array in the top drawer of his desk. The interfering contours to any other station reportedly didn't leave leave the footprint of the land it was built on.
 
The former WDGY/KFAN Minneapolis has always been a 9-tower array. It started out with nine free-standing towers at its original site, then moved across the Mississippi to be rebuilt with a similar 3 x 3 config of guyed sticks. The station tried to get 50kw at night back in the 60s from its original site but couldn't keep the array in, so it operated for years with, IIRC, 30kw DA-N pursuant to a succession of STAs.

The Doctor George Young (hence the calls) array was largely destroyed in recent years in a tornado. I wonder if anyone knows if 1130 has been rebuilt?

CJRN Niagara Falls ON operates on 710 from a ten-tower array. I had heard that CFGM operated with a FIFTEEN tower system on 1320 (3 x 5) but it's interesting to get an authoritative account of 13 sticks. I was PD at 13Q Pittsburgh when CFGM was co-channel and they were a persistent interference problem for us during critical hours.
 
In Canada, there's been a big push to the FM band. In Ottawa (pop 1.3M), much of the AM band is vacant except for 3 signals. In moving to the FM band, it's required that you turn in your AM ticket for the FM allocation.

Here's a video of a 9 tower array turned into a zero tower array after a move to FM:
http://www.youtube.com/watch?v=LODWI8skP_0

I know of one AM station in Montreal with 5 towers that turned into a Wal-Mart after turning in the ticket for an FM frequency.
 
WNTIRadio said:
That has to be one of the most mutated looking night patterns I've ever seen.

12 towers, plus 4 more for the daytime. That's lots of transmission line...
Click to expand...
.



Try to duplex/triplex on that array.
Talk about a major project!
 
Dave Hultsman, the former CE of KLIF in Dallas, posted interesting stories on an engineering blog about the legendary Rockwall night site. He was responsible for building the thing back in 1969. While the new array was under construction Dave related how he was responsible for the dayime 4-tower array, the existing 5-tower 1kw site, plus the new 12 tower 5kw DA-N then under construction - a total of 21 towers for ONE AM station.

Dave also wrote about the odd decision to use unjacketed CATV cable for the sampling system (the equal-length sampling lines for twelve towers must have made for massive coils of line being buried for the towers nearest the Tx building.) The cable started electrolytically reacting with the acidic soil so a DC voltage developed between the conductors. If someone were to connect all 12 towers' sampling lines in series, you would have had a 100-acre 9-volt battery. I assume they had to dig up all the line and start over. I can't remember if Dave discovered the sampling line problem before they started installing the ground system, but just thinking about it makes my head hurt.
 
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