I am always thinking of antenna projects. Here is one I came up with to entertain myself over Thanksgiving break.

Many people who have a 1.2ghz radio do not have an antenna for it.

This is a simple 1/4 wave antenna that can be built in about 15 minutes for the 1.2ghz band.

Material list is as follows…

  1. Mason Jar Lid Like this.
  2. N-Connecter to PL-259 connector adapter. Like this.
  3. Almost 3″ of bare #6 Like this.
  4. The coupling ring from a broken PL-259.

 

Construction is as simple as drilling a hole thru the lid, snipping off a measured length of wire, and assembling the parts as pictured.

 

The antenna should be installed with the least amount of feed line possible, due to the tremendous loss it presents at these frequencies.

If you have a VNA, the antenna can be fine tuned by moving the copper wire up and down by tiny increments.

If you do not have a VNA, just use the SWR meter on the radio, as the antenna should be very close to perfect at the length pictured.

Also, screwing a mason jar over the top would make for a good outdoor antenna, however, feedline length is such an issue that having the antenna in the shack is usually the best bet.

Feedline loss calculator

 

Cheers!

 

PS

This technique works on 70cm with a cookie tin or 2m with a pizza pan.

I also use a barrel connector instead of the N-adapter for 2m.

(70cm Cookie-tin antenna)

 

 

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