Image: First page of original article. See VK8BN link for the complete article. (Click on image for larger view. )
Why is the Slim Jim so much more efficient than the popular 5/8 wave or other ground plane
antennas?
The Slim Jim vertical angle of radiation is almost parallel to ground so maximum radiation is
where it is needed: straight out and in all directions. The vertical angle from the Slim Jim is about 8 degrees, while the common 5/8th wave ground plane antenna is about 32 degrees. With all ground planes, including those with radials a wavelength long, the vertical angle radiation is tilted upwards at an angle of 30 degrees or more.
This gives the Slim Jim a "gain" over a 5/8th wave of about 6dB when measured parallel to the
ground!
Herewith some interesting links on the Slim Jim Antenna:
Build the Slim JIM Antenna by Jose I. Calderon, DU1ANV
Slim Jim and J-Pole Calculator M0UKD
The Slim Jim Antenna, VK8BN (Contains original published article by F.C. JUDD, G2BCX)
