Category Archives: antennas

2.4GHz Wifi corner reflector 

First Harmonic (FH) was getting patchy wifi coverage to his desktop computer in his bedroom.  The obvious thing would be to invest in a new multiband wifi modem/router, one of those things that looks like a UFO with spiky antennas for its multiple bands.  But the situation presented a good opportunity for some basic UHF antenna experiments over this short unlicensed duplex data link. Discussion of the popular Cantenna suggested lower performance than many have claimed due to the small size of Pringles/Milo cans at 2.4GHz. A repurposed satellite TV dish of diameter 1.2m or more seems to be the best option.  Not having one, and needing a solution that would not turn FH’s bedroom into a junkyard, I opted for a homebrew corner reflector based on one of the many online designs.

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A center-loaded squid pole vertical for 7MHz

A 40 meter dipole in the conventional or inverted-vee configuration is a fine antenna for portable operation, providing reliable communication around the southern states during the daytime . My first few SOTA activations used a 40 meter dipole slung from branches at 5 or 6 meters.  It worked perfectly.  Next I purchased a 9 meter squid pole from which the dipole was hung, albeit from the second or third telescopic segment down from the tip for rigidity.  This eliminated the need for a convenient branch and the lead weight swinging, and the ever-present risk of missed shots getting tangled in out-of-reach branches.  But at times the task of walking out from the activation point and tying off the two 10 meter wire elements to suitable tree branches felt a bit tiresome, and on some summits impractical.  The popular end fed dipoles preferred by many current activators span a similar lineal distance, although they allow the radio to be positioned close to the feed point and dispense with the 10 meter length of coax required to feed the center-supported dipole.

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The parts that make up the center-loaded vertical — the blue fishing spool holds the driven element wire and its loading coil. The red spool holds the 4 radials with banana plugs. The termination box and 3 meters of coax provide the feed.

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