MySondy RadioSonde Antenna 403 MHz

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This is an quarter wave ground plane antenna I designed to track weather balloons transmitting around 403 Mhz. Based on calculations here: https://m0ukd.com/calculators/quarter-wave-ground-plane-antenna-calculator/ What you'll need About 1 meter of 14 gauge solid copper wire, stripped About 20 cm of thinner gauge copper wire, stipped An antenna cable with an end matching whatever receiver you want to connect the antenna to. - If you want to connect it to a LilyGo TTGO MySondy receiver you'll want something like SMA Male to SMA Male Cable, 2-Pack 20inch Antenna Extender Cable - If you want to connect it to a RTL-SDR adapter you can cut the antenna off the cable that came with it and use that cable. Assembly: Print the base, top and top tube Run four lengths of 14 gauge copper wire down the four tubes that make the pyramid shape. I found it easiest to leave an inch of wire sticking up through the top of the hole and bend it over the edges of the hole. Take the thinner wire, wrap it around the four wires where they come out of the pyramid (in the gape between the pyramid and the cylinder above it) and solder the thin wire to those four wires, leaving a hole between the four wires for the antenna cable. Once the four pyramid wires are soldered, cut them off just above the solder (in the gap between the pyramid and top round part) Cut a length of 14 gauge copper wire 7" (17.7 cm) Cut off and strip the end of the antenna wire (opposite end from the one that connects to you receiver). Strip it in a stepped fashion, so you can keep a length of the braided shield separate/insulated from the center core wire. Solder the center core of the antenna wire to an end of the 7" copper wire Solder the braided shield of the antenna wire to the thin wire you soldered to the four pyramid wires. Slide the tube and the top bushing over the 7" wire so they stick up out of the anteann Glue in place if needed/desired Using this an the LilyGo MySonde receiver I am able to pick up weather balloon signals as far as 130 miles away, with the antenna placed inside the house next to an upstairs window.