Wavelength=234/frequency in megahertz
Assumption: antenna broke for your GMRS FRS radio.
Tools: wire cutters, needle nosed pliers, measurement tool. (All are found on a Leatherman ® tool)
Parts: wire (electric fence wire, home electrical wire, coat hanger, barbed wire, etc) a SO-239 Antenna connector (female).
Given the GMRS FRS service shares some of the same frequencies we will need to know where those frequencies are. Channels 1-7 and 15-22 all are found between 462.550 and 462.725Mhz. going for the middle of those we find the frequency of 462.637
Plug that into the formula. 234/462.637 and you get a measurement in feet.
.5057 or just over 6 inches. (15.4cm)
Cut your a section of wire to this length or slightly longer. Next we'll cut the radials. They are 12% longer so 17.25cm but we'll cut them even longer for this Antenna. Cut four 7in sections.
Assembly: place the 6in section into the center of the so-239 connector. Using a lighter (unless you have access to a soldering iron in the woods) heat the wire and connector and solder them together. Note: solder flows to the heat.
Once completed, attach the radials by placing 1/2 inch of the radial through the chassis mounting holes and crimp them to the so-239. Soldering is preferred here to ensure good electrical connections.
Angle the radials to approximately 45° down this increases the impedance from 35 ohms to 50 ohms for coaxial matching. Hang the Antenna and make contact
This is NOT my design.