[Towertalk] tilted LPDAs

Joe Reisert jreisert@jlc.net
Wed, 20 Mar 2002 19:16:28 -0500


Hi Jim,

I hope we haven't been confusing things with the so called tilted LPDA's.

LPDA design is quite different than Yagi design. Each element is split and 
there are two hot booms placed in the same plane (parallel to each other). 
One side of the split element connects to one boom and the complementary 
one to the other boom and then alternated as you proceed down the boom. I'm 
sure we are all familiar with that approach which is the common type of 
LPDAs we use nowadays.

However, in the early days (1950 through 1960's) of LPDA design, some of 
the first designs used hot booms were often placed with a 30-45 degree 
angle between them (instead of parallel to each other). The elements were 
still connected as above. However, as you proceed away form the feed point, 
the matching complementary pairs were placed further apart. This gives the 
appearance of stacking.

I hope the above is clear.

73,

Joe, W1JR


At 11:55 AM 3/20/2002 -0600, James H. Fitzpatrick wrote:
>I saw the tilted LPDAs near Champaign in August 1982 when I drove by while
>moving to California. I wondered then what it was all about. Now 20 yrs
>later I found out.It pays to subscribe to towertalk ;>)
>
>Jim
>
>WI9WI
>
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