build cheap yagi antenna

Controlled Impedance "Cheap" Antennas Kent Britain WASVJB If you're planning to build an E ME array, don't use thes e antennas. But if you want to put together a VHF Rover with less than $500 in the .ant ennas, read on. The simplifi ed feed uses the struc ture of the antenna itself for impedance matching. So the design started with the feed and the element s were built around it. Typ ically a hig h gain ante nna is designed in the computer, then you try to come up with a driven el ement matching arrangement for some weird impedance. I n his design, compromises for the feed impedan ce, asymm etrical feed, simple measurements, wide bandwidth, the ability to grow with the same spacing, and trade offs for a very clean pattern cos t abou t 11 2 dB of gain. But you can bui ld these antennas for about $5 ! The an tennas were designed with YagiMax, tw eaked in NEC, and the driven ele ments experimentall y deter mined on the antenna range. Th e boom is 314" square , or 11 2 X 314" wood. The elements have been made from S ilicon Bronze welding rod, Aluminum rod, H obby tubing, and solid ground wire. You really want to solder to the Driven Element. Silicon Bronze Welding rod, Hobby tubing, and #10 o r #12 solid copper wire have been used to make the driven element. A drop of "Super Glue", Epoxy, or RTV is used to hold the elements in place. 1 4 4 MHz Driven Elemen t: All versions Re f 3 Element Length 41.0 Spacing 0 4 Element Length , 41.0 Spacing 0 6 Element Length 40.5 Spacing 0 Ca n be trimmed 14 4 MH z Driven Element for best SWR + B I d l 11 " 118' dia rod I All Dimensions in inches. All Elements 3/16" dia. While W5U N had very good luck w ith 16 element long boom wood antennas, I felt 6 elements wa s abou t the max for most rovers. The design is pe aked at 144.2 MHz, but performance is st ill good at 146.5 MHz. (Emergency use only!)

build cheap yagi antenna

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