Slim Jim

Slim Jim 2-Metre Aerial

F.C. Judd, G2BCX/SK

From http://www.hamuniverse.com/g2bcxslimjimantenna.html

This is a vertically polarized omnidirectional free space aerial for two metros but which will operate in the same way for higher or lower frequency bands by scaling the dimensions accordingly. It has a radiation efficiency 50% or better than a conventional ground plane due to its low angle radiation, is unobtrusive, has no ground plane radials, and therefore has low wind resistance. The name "Slim Jim" stems from its slender construction (it is only 60 inches long for 2 metro operation) and the use of a J type Integrated Matching Stub (JIM) that facilitates feeding the aerial at the base, thus overcoming any problem of interaction between feeder and aerial. The feed impedance is 50 ohms.

Slim Jim Dimensions (in units of wavelength), from wikipedia.com

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