Here is a Super J Antenna calculator:

Frequency (MHz): 145
Feed point height (m): 1

Element 1 length (m): 0.7071067811865475
Element 2 length (m): 0.3535533905932737

This calculator calculates the Length of the elements of a Super J antenna for a given frequency and feed point height. The formula used is:

length = wavelength / 2 - feed_point_height

where:

• length is the length of the element in meters
• wavelength is the wavelength of the radio waves in meters
• feed_point_height is the height of the feed point of the antenna in meters

The wavelength of the radio waves can be calculated using the formula:

wavelength = c / frequency

where:

• c is the speed of light in meters per second
• frequency is the frequency of the radio waves in hertz

For example, the wavelength of radio waves at 145 MHz is:

wavelength = c / frequency = 299,792,458 m/s / 145 MHz = 2.046 m

So, for a Super J antenna with a frequency of 145 MHz and a feed point height of 1 meter, the lengths of the elements would be:

• Element 1 length = 0.7071067811865475 m
• Element 2 length = 0.3535533905932737 m

This calculator is just a simple example, and there are many other factors that can affect the length of the elements of a Super J antenna. For more accurate results, you should consult a qualified antenna engineer.