(15C) ARRL Antenna Compendium vol-1

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An extract from A Triband Parasitic Vertical Directional Array, Walter J. Schulz, The ARRL Antenna Compendium, Volume 1, 1985, pages 94-100

Vertical directional arrays are employed in AM broadcast stations to protect other radio stations that share the same frequency from interference. In other instances, they are used to direct radiation to a specific target area. It is with that purpose in mind that as radio amateurs we are interested in this type of array …

Directional Array with Parasitic Elements
… The electrical parameters were obtained with a pocket calculator such as the Hewlett-Packard HP-15C …

Algorithm for Finding Currents in Array Elements
… There are a number of systems that will yield these current values. Determinants or Guassian Successive Elimination methods are commonly used. However, with the advent of the pocket calculator, and particular the HP-15C, these methods are already programmed in the calculator. This reduces the design work to just plugging in the values. The two mathematical systems used to solve for currents in the array are included in the appendix.

The Matrix
… we must determine a method to write the impedance matrix in such a way that the HP-15C calculator can handle the matrix …
We are now ready to proceed with the actual keystroke procedure as described in the HP-15C owner's manual.\5.6
Keystroke Sequence …

BEST!
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