Log Periodic

Model

The log periodic antenna can be thought of as an array of varying length dipole antennas, giving it its broadband characteristics. In this application the antenna has 12 arms. The antenna is excitend between the 2 PEC arms which support the ipoles.
The directional properties of the antenna can clearly be seen from the 3-D far-field.

Simulation

The arms of the antenna are bent slightly upward, and therefore the simulations is run with the Conformal FDTD solver. The upper frequency of 5 GHz limits the grid step to 5 mm. The minimum step is chosen as 0.25 mm. A broadband simulation is run covering the spectrum bandwidth of the antenna and far-field data is recorded at several frequencies.

Results

The directional properties of the antenna can clearly be seen from the 3-D far-field. The simulated reflection coefficient shows that this antenna has an operational bandwith of approximately 4.25 GHz.