802.11b Homebrew Antenna Shootout - 2/14/2

My Modified Coffee Cantenna


This design is the same as the Flickenger design except for two things.

  1. I installed the one quarter wavelength driven element (the wire soldered into the N-connector) one quarter guide wavelength from the back of the can. This distance can be determined with these formulas.
    Wg = Standing Wavelength (Guide Wavelength) inside Waveguide in inches
    fo = operating frequency in MHz
    fc = TE11 waveguide cutoff frequency in MHz
    d = diameter of round waveguide antenna in inches
     fc = 6917.26/d 
     Wg = 11802.85/ squareroot(f0 squared - fc squared) 
    Diameter of can: 6.05"
    Length of can: 6.67"
    Distances from back of can to center of driven element (one quarter guide wavelength) - 1.37"

  2. I built the Flickenger design using a Folgers "Classic Roast" can. I built my design in an MJB 'Premium Coffee" can. Premium is certainly better than Classic. Also, MJB is a TLA (three letter abbreviation). Computers like TLAs. MJB probably stands for some cool wireless technology like "MoJo Bandwidth" or "Major Jammin' Broadband".

Given the shape of the back of the can, I may try moving the driven element a little farther foward next time.

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