Air America's night signal

Dan Strassberg
Tue Jan 4 18:05:14 EST 2005

WXKS's night signal is equivalent to 3 kW at an azimuth of 54 (arc) degrees,
which is the center azimuth of the pattern--that is, the azimuth of a line
between the two towers. At zero degrees (due north), the signal is
equivalent to 2 kW. Those equivalent-power values assume that you use WXKS's
pattern RMS of 319.7 mV/m/kW @ 1 km as the radiation produced by the actual
antenna-input power of 1 kW. Another means of reckoning the equivalent power
normalizes to an RMS of 281.7 mV/m/kW @ 1km, which is the RMS
inverse-distance field from a minimum-efficiency radiator for a Class B
station. (Such a radiator would be approximately 56 electrical degrees high,
whereas WXKS's towers are taller than 100 electrical degrees.) If you use
the lower figure for the 1 kW-equivalent signal, you get higher equivalent
powers of about 3.75 kW at 54 (arc) degrees and 2.55 kW at zero (arc)

I don't know what WXKS's NIF (nighttime interference-free) contour is. My
guess is that it's in the neighborhood of 50 mV/m. Fortunately, the short
distance between 99 Revere Beach Parkway and the nearest points of land in
Everett is covered by salt water, so you can use the inverse-distance rule
to compute the signal strength at the water's edge in Everett. I'd be
surprised if that distance were more than 500' (1/6 km) at the closest
point. So WKXS probably puts a nighttime signal of about 2V/m over the
closest point of land in Everett. From there, the signal strength drops off
at something between the square and the cube of the ratio of the distance to
1/6 km. I calculate therefore, that the NIF contour lies approximately 2.5
miles to the northeast. I suspect that nearly all of Everett lies within the
NIF contour. But the signal should be quite listenable at distances at least
twice as great and maybe even further.

Dan Strassberg,
eFax 707-215-6367

----- Original Message -----
From: "Laurence Glavin" <>
To: "Scott Fybush" <>; <>
Sent: Tuesday, January 04, 2005 4:55 PM
Subject: RE: Air America's night signal

> >From: "Scott Fybush" <>
> >To:
> >Subject: RE: Air America's night signal
> >Date: Mon, 03 Jan 2005 22:51:03 -0500
> >
> > As for 1430, the Endicott facility is a barn-burner. I was just
> > there a few weeks ago visiting the TX site. They've got a new BE
> > AM6A transmitter there that gets out well, and the night pattern is
> > a five-tower in-line teardrop that blasts to the northeast (maximum
> > lobe field strength is 1887 mV/m at 1 km, quite impressive for a 5
> > kW station.) And did I mention that it's up on a hill, so the array
> > really launches that skywave towards Boston?
> >
> Right at this minute, about 20 minutes after local sunset in
> January, skywave is very subdued and WXKS is audible 25 miles
> north of Wellington Circle.  A few weeks ago, due to a solar hiccup, there
> was little difference between day and night (one person posted to
> the New York city radio board that he could pick up Stamford's
> outlet at 1400 in the City!) and during that period, I could listen
> to WXKS-AM easily in my home; even WJIB-am at 5 watts was
> at least as audible as it would be during the day if the station's
> switcher failed to boost to 250 watts at sunrise.  So it
> appears that WXKS-AM is legally putting out the equivalent of
> several hundred watts, or even a kilo due north,  NW and NNE...
> yet it is still clobbered by WENE.  In the morning, when I'm on
> route 128 north of Boston, I can pick up the two Marks AND
> Imus on WENE simultaneously!  It's amazing that even Everett
> gets sufficient quieting!
> --
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