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AM directional arrays

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k8jd
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Location: Commerce, MI

AM directional arrays

Post by k8jd » Sun Jun 04, 2023 7:48 pm

I saw an interesting discussion of phased vertical antennas. On QRZ.Com/ sub Antennas towers etc.
Lot of the engineering hams jumped in with modeling software graphics.
Reminds me of my study of AMBC tower arrays in my youth !



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Colonel Flagg
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Re: AM directional arrays

Post by Colonel Flagg » Thu Jun 08, 2023 1:54 pm

How about posting a link to that discussion.

Sounds interesting.


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Ben Zonia
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Re: AM directional arrays

Post by Ben Zonia » Thu Jun 08, 2023 4:24 pm

Here's the original postwar treatment for postwar AM Directional Antennas, from 1949, by Carl E. Smith.

https://worldradiohistory.com/Archive-N ... dition.pdf

Carl E. Smith's other major claim to fame besides radio engineering and the CIE, is that he owned the American Gothic Farmhouse in Eldon, Iowa, where Carl was born, for a while, and which was previously owned by his ancestors. Taking your picture and visiting the farmhouse is a major tourist attraction in Iowa.

Image

Carl E. Smith poses with one of the original models for the painting, Nan Wood, the artist's sister.

Image

More about American Gothic House.

https://americangothichouse.org/house

Carl E. Smith obituary.

http://iagenweb.org/boards/wapello/obit ... ead=414496


"I had a job for a while as an announcer at WWV but I finally quit, because I couldn't stand the hours."

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k8jd
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Location: Commerce, MI

Re: AM directional arrays

Post by k8jd » Thu Jun 22, 2023 8:26 pm

Colonel Flagg wrote:
Thu Jun 08, 2023 1:54 pm
How about posting a link to that discussion.

Sounds interesting.
All I can give you is QRZ.com...
I started reading the pages by Carl Smith and got lost in the math by page 40 !



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Ben Zonia
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Re: AM directional arrays

Post by Ben Zonia » Fri Jun 23, 2023 10:26 am

Notice that the pitchfork tines resemble a three tower in line AM directional antenna. The 1:2:1 arrangement, where the center tower functions as two towers in the same place, with a phase and field ratio that is the "two" center towers added together vectorially, continues to be widely used. This is probably the most versatile and common configuration for multi tower AM DAs, the other being a four tower parallelogram. Dogleg three and four tower arrays started to be used starting around 1940, when many Class III stations increased from 1000 or 500 watts nondirectional nights to 5000 watts directional Nights. Slight dogleg three tower arrangements showed up in the late 1940s, WKNX 1210 being the most obvious example in Michigan, in 1960. It is now three of the four towers in the WJMK 1250 array. WSGW 790, from around 1950, uses a slight dogleg three tower arrangement combined with another near parallelogram row for six towers. The 790 in Eau Claire, WI necessitated that to serve Saginaw and Bay City. Midland was very small then.

It wasn't until supercomputers became more available for design that slight doglegs became more widely used.


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