RE: Tower lighting

[dan.Strassberg@att.net]

Well, most of what I knew about AM DAs a year of two ago 
I had figured out by myself by studying AM patterns, 
particularly as portrayed in the NRC Night Pattern Book. 
My studies became a lot easier when Bob Bittner 
introduced me to the Kodis Web site, which includes data 
on the number and placement of the towers as well as 
information on the tower currents and phases and polar 
plots of the patterns. I still hadn't doped out a whole 
lot though, until I encountered Peter Haas in Santa Cruz 
CA in a couple of newsgroups. Peter has worked as a 
station CE--among other things. He also wrote his MS 
thesis in the 60s on design of medium-wave directional 
arrays. Peter is the one who revealed to me the 
mysteries of the multiplication method. There is also an 
addition method, which Peter calls simpler, but which I 
still don't understand.

Now, bear in mind that Peter and I both have advanced 
degrees in EE. Also bear in mind that few CEs are able 
to design AM DAs. Array design is not normally part of a 
CE's job; it's part of a broadcast consulting engineer's 
job. However, software that has become available in the 
past few years may have brought array design within the 
reach of anyone with a modest technical bent. I haven't 
seen the software, so I don't know. But if the software 
is well designed, the prerequisites for using it 
successfully would seem to be the ability to use a PC, a 
reasonable amount of time, and access to the software. I 
even heard that one package was available as shareware, 
but I don't know its name or whether the "free" version 
is intentionally "crippled" so that you must buy an 
expensive package to do any useful work.

Although I am now at the point where I can analyze some 
arrays--the more straightforward ones, given the tower 
parameters and the pattern, I can't design an array from 
scratch and wouldn't really know how to start, except to 
ask Peter for help.
> Dan,
> 
> Thank you for your post about AM patterns... it was very interesting. I
> always enjoy reading about directional patterns and such and would like to
> learn someday how to calculate them (you've given me some ideas on your
> previous post). After I retire from the Navy, I hope to work toward becoming
> a broadcast engineer type, especially with an AM facility...  Any pointers
> on how folks work toward becoming engineers would sure be appreciated!
> 
> 73s
> 
> Ron Gitschier
> Dutch Caribbean
> 
> > -----Original Message-----
> > From:	Dan Strassberg [SMTP:Dan.Strassberg@worldnet.att.net]
> > Sent:	Monday, April 24, 2000 5:12 AM
> > To:	EM1 GITCHIER
> >  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
> > .... .
> 	<snip>