What are Super-J and Collinear J Antennas?

Earlier discussions had covered J pole antenna and its variant Slim Jim antenna. Now what are Super-J and Collinear J Antennas? They are variants of J pole antenna with higher gain as they have additional radiating element above the standard J pole antenna with appropriate phasing arrangement to increase the gain. The figure by Crcwiki from Wikipedia illustrates all the four types of J pole antennas. While Super-J uses a quarter wave phasing stub, Collinear J-Pole uses a phasing coil with physical length of 0.2 wavelength, which will give a more sleek appearance for the antenna. Both versions may give a gain of about 3 dB over a conventional J-pole or half wave antenna. Phasing section is required between two elements of the antenna for them to radiate in phase. In fact, the phasing coil is part of all collinear antennas like my CP22E VHF antenna.

For anyone planning to construct one of these antenna, more details are available in an article by KX4O. He describes the various ways in which the phasing quarterwave stub can be implemented. There is also a description on how to construct the phasing coil for 2m collinear J-pole antenna. Several pictures of radiation pattern of the antenna obtained by software modelling are also there on that page. I was quite surprised to find that the images on Wikipedia page have been contributed by KX4O, John S. Huggins, aka crcwiki! Here is another image comparing the radiation pattern of various types of J-pole antennas shown above. Creative Commons Attribution-Share Alike 4.0 International license. KX4Os phasing coil for 2m was made of #12 solid copper wire wrapped 22 times around 3/4 inch PVC resulting in a coil diameter a little over 1 inch. Length of the phasing coil was 16.5 inches. Diagrams and pictures are available at his website.