2m 2 Meter 3 Element Quad Antenna

This is an implementation of the 2m quad antenna developed by Clarence C. Moore W9LZX.

This is the first proper antenna I have built. It requires very little material and is quite cheap. I was able to build it with material I already had on hand.

Creativity and resourcefulness are definitely part of the amateur radio hobby, but I figured by writing up this antenna build, I might be able to give people ideas and save someone some time.

Building this requires a some experience with basic woodworking - cutting and drilling.

Most of this was built out of a discarded pallet and other lumber scraps.

Frame

• 6 pieces of lumber ½" x 2" in the following lengths: 2 @ 30", 2 @ 31", 2 @ 32"
  • From store: 2pcs of 1-in x 2-in x 8-ft (½" width is too expensive)
    
    • I ripped the crossmembers of a disused pallet in half
• 2 pieces of 2" x 2" approx 4" long
  • Store: a 2x2
    
    • If you don't have 2" x 2" you can make these out of spare 2x4 or 2x6
• 3 pcs of 10/32 bolts, 2 inches long, steel, 6 washers and 3 pcs wingnut bolts
• 12 pc of 10/32 bolts, 2 inches long, nylon (steel may work, but may affect tuning)

Base & Mast

• 1pc 2x6 lumber, 4'
• L brackets, or if you want fancy, a cabinet hinge that opens to 90°
• 2 pieces of 7" x 7" board at least ½" thick
  • From store: two of those 1 ft square pieces
    • OSB or plywood you have laying around will work
• 1pc each of 2" and ½" PVC, both 4ft long
• ½" dowel rod, 4 ft long (optional - just to stiffen the center)

The sparky bits

• 20' 10" (250") of 12ga wire (14ga is fine, stranded, solid doesn't matter)
• a short piece of 50Ω coax: RG58 or RG8x
• Regular solder and soldering iron

Tools

• ⅞" hole saw (for ½" pipe)
• 2½" hole saw (for 2" pipe)
• Drill with 3/16 drill bit & small drill bit for pre-tapping holes, driver for screws
• Wood screws
• Zipties

Using the ½" (or, 1") by 2 wood, make the following lengths:

2 pcs of 32", 2 pcs of 31", 2 pcs of 30". as you make them, label them by length.

Using the 3/16 bit, drill a hole 1½" from the end of each board. Insert the 10/32 vinyl bolt into this hole, with the gap between the board and the head of the bolt.

In the dead center of the same pieces, drill a 3/16 hole. In each of the 3 3/16" holes, put a washer on a 10/32 bolt, push it through the hole, on the other side, a washer and wingnut.

You should now have 3 separate crosses with a bolt hinge in the middle. Tthe 30" is the director, the 31" is the driver, the 32" is the reflector.

Do the following for each cross:

Set the crossmembers at 90°, tighten the wingnuts.

With the ⅞" hole saw, drill as close to the wingnut as possible while still leaving space to move it. The idea being, you'll take out all the wood on one of the crossmembers, but only a half circle on the other one. Do this once for each crossmember to create a hole to hang each of them on the ½" PVC.

Through the two pieces of 7"x7" board, drill a 2" hole. Take those two boards, and using the spacers of 2x2", separate them. Then drill this sandwich together. Then drill this sandwich to the 2x6, creating a base. Use the L brackets to add the other legs to the base.

Near the top of the 2" PVC, use the ⅞" hole saw to drill a hole through both sides, a few inches from the top.

You should have vinyl 10/32 bolts in each end of the crossmembers. Use the shortest cut of wire on the shortest cross,

The cuts of wire are as follows according to the source material :

• Reflector total length in inches = 86.76 inches - 7' 2¾"
• Driven element length total inches = 83.05 inches - 6' 11"
• Director element length total inches = 79.33 inches. - 6' 7⅜"

Wind those wires around the crossmembers making a square shape. The crossmembers will naturally fall opposite the point of the center drill point, so it's recommended to make the ends stop there -- except for the driven element. Make sure the driven element's ends are on the side for vertical polarization. This isn't a big problem, it's not that hard with this design to rotate the elements, just requires something to hold the elements on the mast.

Once you've got the ends of the wire in place, use a staple gun or tape to hold the wires in place, and wire your coax, shield to one wire, center to another.

By this point, you should have the gist of what's going on. The final measurements from reflector to driven elements are 14.25 inches and for driven element to director 18 inches. Use cable ties to keep everything in place and together.

A nanoVNA shows the lowest return loss is at 143.88 MHz indicating that the antenna is too long. Thus, some trimming and adjusting is in order.