Tube Radio Australia

Build Your Own Log Periodic Antenna Systemů

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 ensure 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 respect 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 given in the figure. Note that the LPDA feed includes a 180-degree phase shift by the nature of its standard feed.

Specify the following: