RE: Tower lighting

[EM1 GITCHIER <RGITSCHIER@doyle.navy.mil>]

> -----Original Message-----
> From:	Dan Strassberg [SMTP:Dan.Strassberg@worldnet.att.net]
> Sent:	Monday, April 24, 2000 5:12 AM
> To:	EM1 GITCHIER
> Cc:	
> Subject:	Re: Tower lighting
> 
> A goodly percentage of four-tower arrays are either rectangles or
> parallelograms. In many such cases, the spacing along one axis is roughly
> 90
> degrees whereas the spacing along the other axis is roughly 180 degrees.
> Such a four-tower array is a classic "multiplication-method" design. If
> you
> take either pair of towers that are 180 degrees apart, those two towers,
> by
> themseleves, if fed equal power in-phase, would produce a figure-eight
> pattern with its major axis perpendicular to the line between the towers.
> If
> you also feed equal powers (same magnitude as you used for the first pair)
> in phase to the second 180-degree pair but make the phase 90 degrees from
> that of the first pair, you get a unidirectional, fairly narrow pattern
> whose maximum radiation lies along the line that joins either 90-degree
> pair. This happens because the unidirectional cardioid patterns that
> either
> 90-degree pair would produce are multiplied by the figure-eight patterns
> that either 180-degree pair would produce. So if the far-apart pairs in
> PJB's array are 180 degrees apart along an east-west line and the
> close-together pairs are 90 degrees apart along a north-south line, it
> could
> be that the array was designed to send maximum radiation either to the
> north
> or the south. Moreover, the array could be designed so that when the
> station
> chooses, it can change patterns to send the signal in one of those two
> directions but not in the other, enabling separate sevices to the US and
> South America at different times--all the while protecting the Mexican 800
> in Ciudad Juarez. Moreover, by using either one of the 180-degree pairs by
> itself, PJB could serve both the US and South America simultaneously.
> 
> A number of six-tower arrays use an extension of this approach. If you
> place
> three towers in a line, space them 180-degrees apart, and feed power to
> them
> in phase in a 1:2:1 ratio, you get a narrower figure-eight pattern than
> you
> do with just two towers 180 degrees apart fed equal powers in phase. Now
> add
> a second line of towers with the same spacing and place this second line
> 90
> degrees from the first line. Feed the towers in this line powers equal to
> what you feed their closest neighbors in the first line, but make the
> phase
> of the current you feed to the second line 90 degrees with respect to the
> current you feed to the corresponding towers in the first line. Now you
> get
> a very narrow unidirectional pattern parallel to the lines between the
> 90-degree-spaced pairs.
> 
> All sorts of variations are possible. the 90-degree-spaced pairs do not
> have
> to be (and usually aren't) at right angles to the 180-degree-spaced pairs.
> The "180" and "90" degree spacing don't have to be (and usually aren't)
> precisely 180 and 90 degrees. The current ratios in the two 180-degree
> lines
> don't have to be (and usually aren't) exactly equal. And so on. So it's
> quite possible to "tweak" these designs.
> 
> --
> 
> Dan Strassberg, dan.strassberg@worldnet.att.net
> Phone: 1-617-558-4205, eFax: 1-707-215-6367
> 
> -----Original Message-----
> From: EM1 GITCHIER <RGITSCHIER@doyle.navy.mil>
> To: boston-radio-interest@bostonradio.org
> <boston-radio-interest@bostonradio.org>
> Date: Sunday, April 23, 2000 1:18 PM
> Subject: Tower lighting
> 
> 
> >> As our exteemed list partner the Good Mr. Bittner pointed out to me,
> yes
> >> indeed, the four towers of PJB 800khz, Trans World Radio form a
> rectangle.
> >> The distances between the east-west-erly tower azimuths seem to be
> shorter
> >> spaced as compared to the pair of towers on a North-South-erly
> direction
> >> (undoubtedtly a descriptive faux-pax due to too much island cheer or
> >> massive
> >> dosage of RF...). Just verified that for myself via a moonlit bike hike
> >> down
> >> to the southern tip of the island to the site. Unfortunately, no one
> was
> >> manning the station, just a gate guard and power plant operator was
> there
> >> to
> >> greet me. My clue should of been no one was answering the phone...
> ahh,
> >> automation. What happened to the good old days with engineers
> handcuffed
> >> to
> >> the transmitter cabinets? They're long gone, chum, long gone....
> >>
> >> Now l'm going to go outside the ship and see if I can pull in the
> mighty
> >> 800
> >> WCCM once I figure how to null this powerhouse from about 7 to 10 miles
> >> away. lol....
> >>
> >> Incidentially, about 20% or so of their beacon lights are extinguished.
> >> BTW, not
> >> a single strobe was seen on the Island of Bonaire tonight...
> >>
> >> Ron Gitschier
> >> Bonaire, N.A.
> >>
> >>
> >
>