This is the handheld yagi I use for working satellites when mobile. I swept the entire 420 - 450 MHz 70cm band and found the worst SWR to be1.3:1 .
I made the elements from 1/8th stainless steel tig welding rods. These may be purchased at any welding supply outlet.
The elements can be fastened to the boom in a number of ways. One way is to drill a 1/8th hole through the boom and glue the elements in place. I wanted to have the option of being able to disassemble the antenna for back packing. To accomplish this I took 1/4" bolts and drilled 1/8th holes through the center of the bolts. I then soldered the 1/8th inch stainless elements in place in the bolts. The boom is drilled & tapped on one side of the boom to match the thread on the bolts. the elements are put into place and hand tightened only. The boom also breaks in half for backpacking.
Before assembling the center of the
boom, drill through the boom for the driven elements and insert 6x32
stainless screws from the inside. Use stainless washers and nuts on the
outside to fasten the connectors in place that the braid and center
conductor are attached to on the inside of the boom.