W1TR 3.3 MHz (USAF MARS) Halfwave Sloper

Updated 18-Jun-2006  11:03

 

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The 3.3 Mhz Halfwave Sloper (dipole) is constructed from #10 stranded insulated wire available in most hardware stores.

The feedpoint uses a T-section of PVC pipe.  The coax loops through the PVC pipe to provide strain relief.  Wires are tied using a square knot to the PVC pipe and also to rope which is then tied to tree trunks after going over the tops of trees.  The antenna slopes to the south to give good directivity towards most of USAF MARS Region One.  The “springiness” of the small branches appears to help the wire antennas survive 60 knot winds with little or no damage.

 

This antenna also works acceptably on the 30 Meter amateur band on the 3rd harmonic frequency although the SWR is a little high.  A different RG8X feedline length might yield a better SWR.

 

 

Feedpoint of 3.3 Mhz Halfwave Sloper