k4QKY's MOXON


Completed MOXON at 30 ft. on a push-up mast

 

 Materials

Top left, above photo: Side view of the 3 piece pole bracket assembly.  Note the 4"X6.75"X.25" mast bracket plate which was cut from 6061-T6 aluminum stock with 4 holes drilled to accept two 2 mast clamp U bolts and 2 other holes for attaching the 2 pole holders.  Click here for additional construction details.

Top right, above photo:  Top view of the 3 piece pole bracket assembly.  The two pole holders are made of 1.25 inch electrical conduit and were compressed and bent to form the correct 45  deg angle between opposing poles.  Each pole holder extends outward 7.50" from the mast. Click here for additional construction details.

Center, above photo: This unique compact antenna uses a supporting structure made with four 16 foot telescoping fiberglass crappie fishing poles.  Poles are from Tackleplus, model name Crapple Buster Deluxe, model number 1200-16BW available from www.catfishsupplyco.com.

Left bottom, above photo:  The antenna's two elements are made using 16 gauge tinned copper antenna wire. Dacron line is used to strengthen the structure and to separate the ends of the driven element from the ends of the reflector.

Right bottom, above photo:  Driven element feed point connector.

Not shown:  Miscellaneous hardware, wire tie wraps, electrical tape, etc.

 

Assembly

 

Top left, above photo: Side view of the end of one of the four poles.  Note the ridge which had to be partially filed off in order to make it fit into the end of the pole holders.  Also note double sided tape (backing not removed) to stabilize and cushion the pole in the pole holder.

Top right, above photo:  One of two insulators fashioned from nylon "weed whacker" line. 

Center, above photo: Assembled antenna temporarily mounted on a yellow fiberglass pole for easy access.  Note how each pole fits into the pole bracket assembly.  A green fiberglass "garden stake" runs from the center of the reflector (extreme lower left corner) through a hole in the mast bracket to the antenna feed point.  Note: The completed antenna remained over night 08/22/03 in it's temporary location shown above.  The antenna was entirely intact following a late night severe thunder storm with 45 knot wind gusts attesting to it.

Left bottom, above photo:  Driven element feed point assembly.  Note green fiberglass "garden stake" that supports the feed point and coax.  It runs from the center of the reflector (extreme lower left corner) through a hole in the mast bracket to the antenna feed point.

Right bottom, above photo:  Cable ties and electrical tape securing the corners of each element to the pole spreaders.  Note: The completed antenna's flimsy construction presents some degree of challenge in properly attaching the corners of the driven element and reflector to the pole spreaders at equal distances

 

Construction comments

Isolation of the antenna from the push-up mast:  The antenna was initially attached directly to the mast as shown in the above photograph.  However, upon initial testing it was determined that the metallic mast and pole holders severely detuned the antenna.   To correct this problem, the antenna was electrically isolated from the mast by the insertion of a 4 foot heavy duty wooden broom handle (wrapped with electrical tape)  2 foot into the top section of the push-up mast.  The pole bracket assembly was then bolted to the top of the broom handle.  Subsequent SWR measurements indicate that the metallic pole bracket itself may be the culprit.  A non-metallic alternative pole bracket assembly is currently being considered.

Antenna dimensions calculated by the MoxGen program are generally valid:  Most builders of the MOXON will not find it necessary to lengthen or shorten any of the wire lengths.

Difficulty making electrical tape stick to slippery poles.    Electrical tape was used to tape each pole joint as well as attaching the corners of each wire element to the poles.  Lightly sanding areas of the pole before taping helps alleviate this problem.

The tradeoff to building a light weight antenna is reduced rigidity.    The antenna so light weight that it is easily rotated by hand.    The ends of each pole will naturally droop downward (like an umbrella) depending on the degree of tension applied to the wire elements resulting from where they have been attached to the poles.  Employing a support pole from the center of the reflector through the pole bracket assembly to the driven element feed point helps stabilize the elements as well as the coax feed line.

Note:  Click here  to read Don's evaluation of his MOXON antenna's performance.

Email Don at  for additional information about his  MOXON.

 

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