Antenna Project: 6 ELEMENT WIRE BEAM FOR 144 Mhz

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Antenna Project:

6 ELEMENT WIRE BEAM FOR 144 MHz

By DU1RZ

I started this project after building my first mono band moxon for 15 mtr band. My first 2 meter moxon was a regular 2 element design, using some leftover #14 gauge wire from the 15 mtr moxon and pvc pipes. It was quite easy, since this one is a lot smaller. Using the MOXGEN software the calculated dimensions for the elements were:

From this two element design I decided to experiment on adding another band for 70 cm and placed another moxon rectangle calculated for 70 cm. It was quite tedious incorporating another antenna in the middle and I had to consider combining the impedances of the 2 separate antennas. Although I was able to make one, another idea came up on making it a multi element beam like a yagi which was initially a mono bander for 2 mtrs.

MULTI ELEMENT WIRE BEAM DESIGN

Element Dimensions

I have been using this antenna sparingly since 2010 on vhf (since I don’t have a uhf transceiver). I never knew it was also resonant on 70 cm until DU1YMD asked for the design and made one. He tried measuring the swr on uhf and found it to be resonant too on 70cm.

Last year DV1XND brought along some Boy Scouts from our area to my QTH, they were eager to learn and be ham operators, and asked me to help them make this antenna. So we started with the moxon antenna, then we made the 3 element tape measure yagi beam which was also successful. Since the design for the tape measure antenna is available online we are sharing with you the design for the 6 element moxon.

PVC FRAME ASSEMBLY LAYOUT

ANTENNA DESIGN WITH PVC FRAME SUPERIMPOSED

Wire element materials :

6 Mtrs #14 gauge wire (stranded or solid, but we prefer stranded).
Cable tie – to hold the wire elements strapped into the frame.
SO 239 for the feed point. This is optional , you can connect your Coax directly to the feed.

Assembly:

Assemble your frame , follow the measurements carefully ( Metric Unit). Drill a hole on one of the tee connectors , for the middle pole.

After completing the frame, drill holes on the top and bottom pvc for the wire elements. They should be aligned ,follow the measurement between elements.

You may now insert the wire elements on your assembled frame. Cut the wires according to their specified lengths. Use your cable tie to secure the elements.( Try using UV resistant cable ties)

The Driven Element must have some allowance for tuning , measure the point in the middle where you will place your feed point.

Measure the SWR. Trim or fold the excess length of the Driven element to tune your antenna to the Resonant Frequency ( 145 Mhz)

Observations:

Easy construction because of the materials (wires and pvcs) compared to aluminum .
Cost less compared to aluminum yagi antennas.
Any starting ham can make this project using available materials they have from their junk pile.
The results we obtained were pretty impressive considering that some of the materials we used were salvaged from leftover projects.
The SWR we measured ranged from 1.1: 1 to 1.4 : 1.