This morning I noticed that the field strength of my AM station was higher than usual as monitored by a receiver with a meter using an indoor antenna. The transmitter is ground mounted over radials and feeds 85 mW into a base coil loaded 3 meter antenna. Previously, the car radio range has been observed to be 1 mile listenable and 1.3 miles identifiable as my station by program content...
While out on an errand today I checked the range and it was 1.8 miles listenable and 2.4 miles identifiable.
It would be nice if this was the norm but I suspect it is an anomaly. My best guess is that the ground conductivity conditions are improved today.. I have noticed in the past that when the ground is frozen the range improves. Today, the ground is frozen, it is 41 degrees F, and we have had 1/10 inch of rain overnignt. This probably has raised the ground conductivity considerably and thereby improved the range. The transmitter power is the same as usual so it is most likely the change in ground conditions that is causing this.
Strange that frozen soil would give this result but considering that to be frozen there must be moisture present then it sort of makes sense.
Neil
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The Winter local DX season, that's what I like to call it, just like Christmas and the holidays, it brings us all "closer together", hopefully, and some fringe stations are much more listenable.
I've thought some of it is the lower noise at this time of year, I guess that would be less 'thermal agitation' noise, and better ground between you and the station.
I haven't gotten to test it on my AM, not having a solid install that's stayed the same for too long, but have heard other Part 15 friends talking about their stations getting out better because it's Winter.
couldn't be explained.
Hi Neil, it's nice to see your report.
My coil was homemade and not watertight.
(This gets further and further into the past.
It must be 8 or 10 years ago now.)
My set-up achieved ranges that were
different in different directions. (For
lack of a better way to say it.) In
our routine travels around town we
stopped in many parking lots. I was
always checking the car radio - and my
wonderful wife - - put up with it all.
One of my kids was taking swimming
lessons at a pool that was almost exactly
3 miles from our house.
I never heard my signal there - in the many
times we were parked at that pool. Well - -
except for that ONE time. On that unexplainable
day it was there - - right on 1700 kHz.
The signal was weak and in the noise
but I could identify the song that was playing.
The next time I came back 1700 kHz was empty.
Nothing there - nobody home. I don't
know why.
Very best wishes
Brooce, Part 15 Hartford CT
I've noticed my range usually increases after it rains and that my signal strength dropped in the summer. Now that its winter again my range is returning to what it initially was when I first setup the Rangemaster last January.
I've also found the agricultural activities that surround the transmit site also affect my signal, particularly around irrigation time. Not to mention the nearby fertilizer plant and whatever they do on their tracts of land.
If I am not mistaken, water (frozen or liquid) is a great conductor of electromagnetic signals (radio waves). So that might be a part of the puzzle.