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AM Frequency of the Week: 890

No - basically saying that it is our imagination doesn't fly. ... The only differences - (1) higher levels of ambient noise thanks to poorly designed electronics in use - a variable I have eliminated by repairing the problems in my listening environment. (2) more clutter on the band in the form of more stations, US and Mexican, than there used to be. ...

Yes, you added two more conditions that can affect the useful reception of AM broadcast stations (thanks).

As for attributing one's observations about the reception of WLS to degraded performance of the WLS transmit facilities -- the most reliable way to determine whether or not they are radiating the field shown for them in FCC records is to measure it just beyond the near-field radius of their antenna system (typically 1 km away from the tower base), using a calibrated field intensity meter.

I know from conversations with a former C.E. of WLS that such measurements have been taken routinely, and had the value expected for the WLS tower height, ground system, applied r-f power, and frequency.
 
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In northwest San Antonio...

Daytime is a fairly strong KVOZ "Radio Cristiana" in Del Mar Hills near Laredo.

Nighttime has KVOZ dominating but weaker, with WLS often underneath and usually readable though weak. Sometimes XEAK "La Mejor" in Acámbaro will pop up for a little while. I've heard a weak KJME briefly a few times at night and sunrise. Also, I heard WHJA once while driving home on a December night almost three years ago.

A few years back I logged Radio Progreso, but I haven't heard it in quite a while. I don't imagine it's still running 200 kW?
 
I know from conversations with a former C.E. of WLS that such measurements have been taken routinely, and had the value expected for the WLS tower height, ground system, applied r-f power, and frequency.

Okay, so as a non-engineer, here's my super-dumb stupid question...

The measurements are being taken 1km....or roughly .62 mile from the tower. My recall from driving by the area primarily along I-80 (and less commonly U.S. 45), is that the area IMMEDIATELY around the tower is still relatively open. Then begins the development that goes on for miles and wasn't there back during WLS' salad days as a top 40 stagtion. Bottom line is I'm wondering if the more recent degrading of the signal (at least the groundwave) be happening BEYOND the point where the measurements are taken?
 
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"Urban Clutter" vs. AM Broadcast Station Groundwave Propagation

Urban clutter has relatively little affect on the propagation of AM broadcast groundwave signals, because the obstructions are small in terms of the wavelength.

Below is an illustration of this, showing that the groundwave field is the same on both sides of a radial line from an AM broadcast station passing through a large building.

The measurements were taken using a Tecsun portable receiver that displays the voltage present across the r-f input terminals of the receiver, in dBµV (not dBµV/m).
MW_Field_Atten_by_Tall_Building.jpg
 
Yes, you added two more conditions that can affect the useful reception of AM broadcast stations (thanks).

As for attributing one's observations about the reception of WLS to degraded performance of the WLS transmit facilities -- the most reliable way to determine whether or not they are radiating the field shown for them in FCC records is to measure it just beyond the near-field radius of their antenna system (typically 1 km away from the tower base), using a calibrated field intensity meter.

I know from conversations with a former C.E. of WLS that such measurements have been taken routinely, and had the value expected for the WLS tower height, ground system, applied r-f power, and frequency.

Since their current format isn't worth the time of day, let alone the cost of a plane ticket all the way to Chicago with my equipment - I will pass on that one. They can just go right on telling themselves that nothing is wrong. There used to be a time when observations from expert listeners were valued by engineers. That time has obviously passed, because expert listeners like myself refused to join the religion of HD radio. So - just keep on in denial - lack of signal in Houston at night can't possibly indicate a problem with building penetration in Chicago - right?! Or is the problem so acute that it requires an FM station in the middle of downtown to try and penetrate buildings there?
 
Between Detroit and Ann Arbor:

a VERY faint WLS only when I am using my Kiwa Pocket loop antenna in the day time with my Sony 2010

Night - decent WLS as long as I am not too close to the local 910 HD buzz saw

Retro- 1983, listening to Hall and Oates 'Family man' at Tiger stadium on a Walkman, clear as day, as well as 1987 my first AM stereo receiver (Sansui SX-1130) and seeing the stereo light go on, and then some platform motion..lol



in addition, that ever present 1 KHz 'Het'
 
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... lack of signal in Houston at night can't possibly indicate a problem with building penetration in Chicago - right?! Or is the problem so acute that it requires an FM station in the middle of downtown to try and penetrate buildings there?
AM broadcast r-f signals reaching Houston from Chicago arrive via a skywave path, which tends to pass over any possible problems related to building penetration in Chicago.

The reason that VHF-FM signals can be more useful within a high-rise, steel-reinforced structure than AM broadcast signals is due to the shielding the building provides within it for AM broadcast signals. The steel lattice structure having its members physically spaced at 0.1 wavelength intervals and less performs about like a continuous, conducting surface in the medium-wave band. VHF/UHF signals are not so much affected, because of their much shorter wavelengths.
 
In Charleston, 890 AM daytime is WBAJ Blythewood, SC with a religious format. It is a 50kw signal, but signs off at night for WLS, which is usually OK to weak here. It is strong enough to be listenable. A few months ago, a friend of mine from HS was a guest on one of WLS’s Sunday night shows, and I heard her via the OTA signal.

I’ve heard it daytime as far east as Independence, OH this summer when I was DXing outside my hotel. All the Chicago clears were heard from there, except 1000 (there is a Cleveland local on that frequency). 890 was the weakest.
 
I would guesstimate that the strongest groundwaves from that location would be 670, 720, 780, and then 890,
and the strongest skywaves would be 890, 780, 720, and 670 in those orders.
The 560 and 1000 groundwaves might get honorable mentions in some directions.
 
From around St. Marys, Ohio, about 200 miles east-southeast of Chicago (to be more specific, 60 miles southeast of Fort Wayne), my experience with the Chicago groundwaves are 720 and 670 at about equal strength, then 780, then 890 and 1000. The latter three are pretty weak daytime, especially with WBBM running IBOC. Personally I would put 670 a notch ahead of 720 because 720 gets clobbered by slop from WJYM on 730 in Bowling Green, Ohio.
Maybe I just never looked for it, but I don't remember ever hearing WIND there. Even if so, WKRC on 550 next door is pretty solid in that area day and night.
 
The 560 and 1000 groundwaves might get honorable mentions in some directions.

WIND throws its main lobe to the northwest day and night, with a significant secondary lobe to the southeast on day pattern. The signal to the east and west is significantly less, which would explain why the signal for schmave and gr8oldies is weak or missing entirely. OTOH, WIND's signal in most of Wisconsin is usually comparable to the Chicago blowtorches.
 
AM broadcast r-f signals reaching Houston from Chicago arrive via a skywave path, which tends to pass over any possible problems related to building penetration in Chicago.

The reason that VHF-FM signals can be more useful within a high-rise, steel-reinforced structure than AM broadcast signals is due to the shielding the building provides within it for AM broadcast signals. The steel lattice structure having its members physically spaced at 0.1 wavelength intervals and less performs about like a continuous, conducting surface in the medium-wave band. VHF/UHF signals are not so much affected, because of their much shorter wavelengths.

The penetration of full class C FM stations into the TI plant in Dallas, which is pretty typical office construction - with ample windows - is somewhere around 12 tp 15 feet. That was measured with professional Agilent test equipment. The towers were about 15 miles away, plainly visible, no obstructions, 100kW. Only 12 to 15 feet penetration. Given the expansive nature of the floor, that would cover about 5% of the office cubicles - except that the outer hallway was about 10 feet wide. So you might reach one layer of office cubicles, maybe 2% of the workers - if they cooperated and put their radios on the wall nearest the window, but not so close that the steel in the cubicle wall attenuated the signal further. In the mean time - AM stations such as WBAP absolutely penetrated deep into the building. Transmitter probably at least 30 miles away. On a cheap walkman, I could get most of the local AMs in all but the noisiest lab areas. Somebody - needs to re-think their basic assumptions and do some real world listening tests in these office buildings!!!!
 
Unlike the old days, I can get 4 stations on 890. Most of the night it's WLS but in the early evening I hear the Cubans over it. In the daytime it's local WJTP the Chinese station (which used to be in English) and in the early morning it's WHNC out of Henderson NC.
 
Building Penetration

... Somebody - needs to re-think their basic assumptions and do some real world listening tests in these office buildings!!!!

Your experience in the structure you described isn't necessarily valid for high-rise urban clutter.

This morning I emailed Warren Shulz, the C.E. of WLS Radio for many years (now retired), and asked:

Do you have any information as to how well the Chgo AMs are able to be listened to inside the high-rise buildings in the Loop?

Would one of the reasons why stations like WBBM (AM) added 105.9 FM from Sears/Willis Tower be related to providing better service to listeners in buildings in the Loop than they were getting from 780 AM?

Below is his reply, quoted here with his written permission:

Downtown buildings are Faraday cages. AM sig. at skin and drops 20 dB a few feet in. I was successful get AM reception with tuned, amplified loop antennas on roof of 12 story TV building. Worked well. Nothing else would do it.

Many AM's like WBBM have paired with FM's to fight noise and shielding in downtown areas. Even 50 kW AM won't make it. In Cgo only WGN has the performance to get into buildings. But man-made noise from devices in office would be a huge noise source that is difficult to overcome.

FM wavelengths will pass thru window openings of the office buildings and no apparent noise makes reception possible.
 
Your experience in the structure you described isn't necessarily valid for high-rise urban clutter.
I appreciate the response from the engineer, and the trouble you went through to get it. I used the TI plant as a worst case scenario, because it is densely built of steel and thick concrete. Due to the nature of the business, they WANT to create a Faraday cage to prevent intellectual property from being received outside. That, and the intentional two story / broad footprint of the structure makes it the perfect "worst case" scenario for building penetration. Some critical functions with especially sensitive information are actually located underground with additional shielding. I was working with the wireless keyboard and wireless mice prototyping efforts for a major US manufacturer, and had top of the line RF equipment to measure field strengths. It was extremely easy to re-tune the equipment to broadcast bands on my lunch hour. At the time, some pretty extraordinary claims were being made about additional power for HD sidebands. I documented about 4 to 5 extra feet, which was a lot considering the best FMs in the market only made it about 12 to 15 feet into the building. HD would still not reach even the first rows of cubicles even with more sideband power, by the way. It just got further across the ten foot gap. I am talking about the standard 60 dB threshold, somebody with a sensitive radio and big antenna could always do better. And a couple of the managers did just that - a 70's era receiver with a dipole or rabbit ears or some other indoor antenna. If they were within 30 feet of the window, they could get something. But they had offices and their receiver wouldn't bother anybody. People who listened to radio listened to AM because it was strong and reliable. I was in the downstairs think tank and WBAP came right in, not a problem in the world. Very ordinary radio without a large ferrite bar or anything. I was in an office park in Houston for 3 years, same steel / concrete construction. I put my radio within a few feet of the window, I got - drum roll - WBAP - static free, no problem whatsoever. That is well over 200 miles and still penetrating commercial construction. Yes I know KTRH duplicates the programming - but the ____ radio dial string broke and since the station was coming in static free I just didn't bother to haul it back home to fix it. I eventually did. But WBAP had a better morning show so I left it on WBAP.

So - as to my theory about why AM penetrates so much better than FM? The engineer was invoking the slot antenna theory, which works well I suppose. But the slot can be 1/20 of the wavelength and still allow signals in. Faraday cage? Nope. Any slot - intentional or otherwise - and you don't have a Faraday cage. Not even close. I have worked with Faraday cages - real ones - and there is not a signal inside. Not AM, not FM, not cell - nothing. I did take a radio in out of curioscity - it was amazing to have not a single station on it. Of course no cell service either! But you cannot characterize office buildings or high rises as Faraday cages. There is something about the long wavelength of AM that seems to work better in the commercial construction I am in. New job - new building - same story. I am about 20 feet in - a full class C FM station only 20 miles away - nothing. Gone. WBAP - finally attenuated a bit. some static. KTRH - blasts in. A mile from I-10 in Houston. Same with a job I had 6 years ago. Same with the doctor's office - IN A HIGH RISE building. Sony SRF-A1. FM has real problems. AM blasts right in. Even WBAP - in HOUSTON if I am within a few feet of window. WLS - flamethrower signal - it should be all over downtown Chicago in and out of buildings. Maybe ground conductivity is the problem - something is different. There is some variable we aren't considering.
 
Baldwin County, Alabama, on the Gulf of Mexico:

Day: Nothing
Night: A really nasty mix of Cuba and WLS. Even when WLS is booming in, it's usually 50/50 with Cuba here. Disappointing, because I'd love to give my little Sony AM stereo Walkman something to hear at night, and I understand they still run C-QUAM after dark.

Since the thread meandered over to in-building penetration, I'd like to offer some observations I've had in various buildings.

When I lived in Birmingham, I worked in a small industrial shop that was mostly computer-free, although there were a lot of motor-driven machines. The building itself was all metal. Worst of all, we were on the western slope of a valley about 2/3rds the way up the side, and all the Birmingham FMs and most of the AMs were behind and "below ground", so to speak.

Despite all those hardships, FM and AM reception was possible everywhere in the building. The full class Cs and C0s were easy to receive even on the cheapest radios. C3s and below were a lot more challenged, and you could forget about any class A unless it was to our east, because then it was like being high up on a ridge. Most of the FMs were 8-14 miles to our west.

The AMs generally fared worse thanks to impulse noise from the motors and the fact that all but a few of the TX sites are even further west. WXJC's 50 kW directional signal from Tarrant was good during the day, and Irondale's local 1480 was only a few miles down the road, so their 5 kW was clear as a bell, and even their nighttime signal was decent, at 28 watts. Everything else was challenging.

A lot of the guys with radios would listen to the Anniston/Oxford area stations despite them being much lower powered and a good 30-40 miles away. It was just a clear view to the east, like being up on a ridge.

Down here in Baldwin County, I snuck (sneaked?) a radio into the local hospital ("Vincent Price Memorial" as the locals call it) one night when I was babysitting a sick family member and the thick concrete building really did a number on everything. The hospital itself is only three stories, and we were on the first floor the whole time, so we were in the belly of the beast. And despite having a cadre of full Cs or close to it, the FMs were not even clear enough to listen to once you got into the maze-like hallways away from windows. Rooms? No problem, but the hallways you might as well have been in a bunker underground. It was neat. There was no skywave reception at all on AM even in the rooms. The only local AM we have has 43 paltry watts at night and was mostly inaudible in the hospital as well. But surprisingly, their 250 watt translator, on the AM stick about 2 miles away, was by far the best FM signal in the entire hospital, even beating the 100 kW stations whose towers were only about 16 miles away over flat terrain.

Having stayed in a lot of hotels over the years, I often made a point if I had the time to walk around the hotel complexes with a radio and go up to a high floor to DX from a hallway window for a hot minute. Frankly, it seems hotels are the worst buildings I've been in for FM and AM reception. AM dies a painful death as soon as get inside these places thanks to all the TVs and electronics. FM is very very spotty in interior halls, even in cheaper hotels constructed of wood.
 
I don't think FM is spotty in the interior halls of hotels. When I was in Gresham, OR at a Hampton Inn five years ago, I had tropo from Seattle and Bellingham. Signals actually got STRONGER on the third floor, and it didn't matter where in the hallway. I tried to stay around the stairs and not the halls in case I saw housekeeping after the breakfast hours. I was able to find a slight null for the 97.1 IBOC, and in came 97.3 KIRO. Helped that I was about 12 miles from the Portland FM transmitters. AM definitely, I had to go outside to DX at night. Good conditions the nights I was there but not much would come in the rooms minus locals and the big 50KW clear channels like KFBK, KGO and KSL. KDXU did make it into the rooms oddly enough.
 
I don't think FM is spotty in the interior halls of hotels.

That may be the case with some reception conditions like tropo, as you say.

But under normal situations, the deeper into a building you get, the more signal attenuation. That's why it is pretty general knowledge that while even below 50 dbu is a usable FM signal in cars and open spaces, it takes around 65 dbu to make it inside buildings.

In my own experience with a lower power New York City signal from the Empire State Building in a hotel just a couple of miles uptown, that signal was fine with a radio held up to the window but when the radio was placed inside the room, it disappeared for the most part. Near the central elevator bank, not even a murmur. Yet the tip of the ESB could be seen from that window.
 
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