Build a 9 dB, 70cm Collinear Antenna from Coax

This article details the construction of a 9 dB, 70cm collinear antenna using inexpensive RG58/U coaxial cable and encased in PVC pipe. It is designed for average use rather than commercial quality or hurricane-force wind resistance. The guide covers the calculation of ½ wavelength for RG58/U coax at 444 MHz, accounting for a velocity factor of 0.66, resulting in 223 millimeters per section. It specifies cutting 8 half-wavelength sections (231mm each to allow for trimming) and connecting them as shown in Figure 1. Instructions include preparing the coax ends by exposing the center conductor and braid, tinning the braid, and soldering the sections. The article also describes adding a ¼ wave element (169mm #16 solid wire) to the top and a ¼ wave aluminum tube (160mm, 5/16 inch) to the bottom, crimped to the braid of the feed point. This project is suitable for amateur radio operators looking to home-brew a 70cm antenna.