How far do your local AM's go during the day?

[radioman148]

690 Jacksonville does well during the day.

 

[trusty]

On a visit to Charleston/Savannah last fall I was very impressed by the signal the the 690 in Jacksonville FL put into both cities, particularly Charleston.
No doubt that salt water path works very well.

One thing about a salt-water path is its consistency. Nothing built on it to increase noise or decrease ground conductivity (if buildings really DO decrease conductivity...)

One thing hasn't been addressed on his thread - especially for the new people (Welcome!):
Take a look at WSM's tower area vs WSB's tower area and ask, "Does covering your ground radials with asphalt affect your signal?"

 

[radioman148]

WOW--why don't they just put lead over it?

 

[rfry]

...One thing hasn't been addressed on his thread ... Does covering your ground radials with asphalt affect your signal?"

Just to note that the FCC requires a "Class A" AM broadcast station such as WSB to produce a minimum value of 362 mV/m at 1 km in the horizontal plane with 1 kW of power applied to its antenna system (which system includes the performance of its functional r-f ground). That minimum field at 1 km for 50 kW of applied power is 362 x SQRT(50) = 2560 mV/m.

From the FCC database, WSB uses a single, 179.3-degree monopole with an FCC "efficiency" of 379.81 mV/m for 1 kW of applied power. Their theoretical field at 1 km then is 2686 mV/m. Both of these values exceed the minimums required by the FCC.

If WSB used a 195-degree monopole they would gain a few tenths of a dB improvement in their groundwave signal, and due to a small reduction in high-angle radiation would reduce the area of nighttime skywave interference with their own groundwave.

But that improvement probably would not be worth the cost needed to produce it.

The nighttime, skywave signal strength of WSB beyond the useful range of their groundwave signal is similar to that of other Class A stations having about the same path lengths and propagation conditions.

 

[K4WRF]

On a visit to Charleston/Savannah last fall I was very impressed by the signal the the 690 in Jacksonville FL put into both cities, particularly Charleston. 
No doubt that salt water path works very well.

One thing about a salt-water path is its consistency. Nothing built on it to increase noise or decrease ground conductivity (if buildings really DO decrease conductivity...)

One thing hasn't been addressed on his thread - especially for the new people (Welcome!):
Take a look at WSM's tower area vs WSB's tower area and ask, "Does covering your ground radials with asphalt affect your signal?"

Apparently not to any significant degree. I saw a study conducted by Palmer Greer And Associates many years ago  that involved measurements made on different ground system configurations under a uniform tower. It seemed the deeper the radials were buried in the ground the result was *slightly* decreased near-field with little or no  difference in the *far field*. Now there is concern that disturbance in the surface soil over large areas could have an impact in local signal (far field)and this has been seen while conducting radial measurements over large areas that were reclaimed strip mines. While measuring over these areas, the FI would drop dramatically but then come back up and continue on the other side. The conductivity might be running about 2 ms/m then drop to 0.5  the return to the 2 ms/m  on the other side.

In the case of WSB and KFI who were co-owned by Cox for a long time, they chose to optimize the value of their land around their towers by allowing the area inside the ground system to be developed. A shopping mall in Atlanta and a distribution complex in Los Angeles. In both these cases, extensive care was taken to protect the ground system and extend it over the top of the adjacent buildings as well as steel structure and metal surface bonding and shielding. Professionals dealing with these facilities relate that there was no significant impact to those signals although anecdotal accounts may disagree. The fact always has been that these areas suffer from very poor soil conductivity, the north Georgia area being one of the worst.

Best regards,

w/

 

[cyberdad]

You say that the signal of WLS has deteriorated over time. However I have had many in person and e-mail contacts with their chief engineer over the last 20+ years, and can report from that that their measured, present-day groundwave field at 1 km is very close to its inverse distance value for the efficiency of their radiator and their applied power -- despite anecdotal/undocumented comments to the contrary.

What is their field strength at the periphery of the market, or in finge areas in adjacent markets?

Non Directional former Class 1 A stations probably have no early readings to compare with toady's readings because they were not required and even if done, they likely don't survive.

I realize this is totally non scientific, but I live 40 miles from the WLS tower & their signal during the day is not as strong as it was 20 or 30 years ago. Also, if you're driving in the Milwaukee area WLS has the noisiest signal of all the 50KW Chicago stations except WYLL.

My (also admittedly non-scientific) experience is similar. And it appears to be confirmed by those measurements taken at the intersection of 894 and 94. At one point I was getting into Milwaukee on business day trips once or twice a month. WLS was noticably weaker in Milwaukee than the three other "1-A" blowtorches, but still plenty strong and clean. Now it's weaker and noisier. (And yes, I know there's more noise out there these days).

Yet given all the chatter here and in other threads about how "degraded" WLS's signal is these days, I was on a road trip to the western portion of the upper Midwest this week....and surprised to find WLS as the strongest Chicago skywave signal. True in three locations on three consecutive nights. Sioux Falls, Winnipeg, and St. Cloud. In fact, in Winnipeg, WLS was the only Chicagoan present. And with a very good signal. WGN and WBBM were absent, while local blowtorch CJOB on 680 blew out any chance for WSCR.

 

[radioman148]

Indeed WLS skywave is still very good. When in Puerto Rico last March WLS was the strongest of the Chicago clears. WGN was more consistent because of less competition on 720, but when WLS came in it was the strongest.