Log Periodic Dipole Array (LPDA)

The field patterns, input impedance for each dipole, overall input impedance and VSWR are computed.
The array is fed at the high frequency end and loaded at the low frequency end.
The LPDA specified by the tau and sigma provided is displayed to enzure a realistic design was specified.
The LPDA is oriented such that the smallest element is at the top and largest element is at the bottom with repspect to the E and H field pattern plots.

The following figure illustrates the geometry of the array. Tau and sigma are the standard defining parameters for log periodic antennas and are defined by the equations givn in the figure. Note that the LPDA feed includes a 180 degree phase shift by the nature of its standard feed.

Specify the following:

• frequency (in MHZ) at which the antenna will operate
  can be a single number or a list: 3000.0 or {3000.0,3100.0,3200.0}
• number of Elements
  must be between 3 and 20 elements
• tau (shortening factor)
• sigma (separation factor)
• length of dipole 1 (largest one in meters)
• element radius Type (1 means fixed; 2 means fixed radius/length ratio)
• element radius value (radius or radius/length)
• Zs (real source impedance)
• Zl (real load impedance)
• Zo (real characteristic impedance of the feed line)
• length of feed between dipole 1 and 2 (meters)
• phase factor (deviation from standard endfire in terms of %of length)
• dynamic range to be diplayed (dB range of interest)
• If you want to have the admittance matrix plot for the array suppressed
  then set Yplot to 0. The admittace matrix varies with frequency and shows the
  coupling between elements as well as the self admittance. It is only for the
  radiating structure and is independent of the feed.

This script was developed at the Center for Computational Electromagnetics (CCEM) in the University of Illinois at Urbana with funding from the Sloan Center for Asynchronous Learning Environments(SCALE).

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