- 12-gauge copper conductors
- height above ground 30 ft
- average ground characteristics
Using the program's 3D features, the following plot shows the complexity of the antenna's radiation pattern at 28.5 MHz. This is an overhead view, with antenna oriented from left to right. Click on the figure to enlarge.
A frequency sweep from 1.8 to 29.7 MHz was made to investigate the behavior of the antenna's impedance at the transmitter end of the feed line. The following figure shows the calculated values of resistance, reactance, impedance, and phase at increments of 0.2 MHz. Numerical values are available in the program's output file, and one set of numbers (at 7.2 MHz) are shown on the figure. Click on the figure to enlage.
It can be seen that the antenna's impedance (green curve) is fairly high (several hundred ohms) at many of the ham band frequencies, confirming the need for a tuner to achieve matching to a 50-ohm transmitter. The program includes a feature for calculating the needed matching components. This could be used to predict the ability of a given tuner to achieve a match at any given frequency.