On-line antenna designer. Calculate the required dimensions for a J Pole antenna construction for any given frequency.
Enter the required frequency in MHz and the antenna designer will calculate the dimensions of the elements as shown below.
The J Pole antenna is a simplified version of the Slim Jim antenna, using the same
matching stub principle. The length of the antenna is three quarter wavelength. It radiates and receives in an omni-directional pattern.
This antenna design does not need a ground plane and is ideal for mounting inside
PVC piping to protect it from the elements.
Performs well and can be used for RX and TX purposes. It can be made from any
common household wiring.. The thicker the wire, the wider the bandwidth of the antenna
from its center frequency.
Frequency calculations are based on radio waves traveling at the speed of light
299 792 458 meters per second.
Side view: ADS-B J Pole
Testing: ADS-B J Pole
Above images show a J Pole built for 1090 MHz using this antenna calculator. Note the coax balan, this is needed to keep current from the antenna off the feed line.
This J Pole antenna design beats the quarter wave 'hands down'. Besides better reception (gain) it also uses less space and is easier to construct because it does not need a ground plane.