Figure 4-2A. COBRA HEAD Figure 4-2B. ANTENNA BASE b. Expedient 292-Type Antenna. Developed for jungle, these antennas, properly used, can improve communications. Their weight and bulk render them impractical for most squad or platoon operations, but the unit can carry the masthead and antenna sections only, and mount them on wood poles or from trees; or they can construct an expedient version (Figure 4-3, Figure 4-4, and Figure 4-5) using any insulated wire and other available material. For example, most any plastic, glass, or rubber items or, if these are unavailable, dry wood, can serve as insulators: (1) Use the planning considerations discussed in the next paragraph to determine the length of the elements (one radiating wire and three ground plane wires) for the desired frequency. Cut these elements (A) from claymore or similar wire. The heavier the gauge, the better, but insulated copper core wire works best. Cut spacing sticks (B) the same length as the ground plane wires. Place the sticks in a triangle and tie their ends together with wire, tape, or rope. Attach an insulator (C) to each corner and one end of each ground-plane wire to each insulator. Bring the loose ends of the ground-plane wires together, attach them to an insulator (C), and tie securely. Strip about 3 inches of insulation from each wire and twist them together. (2) Tie one end of the radiating element wire to the other side of insulator and the other end to another insulator (B). Strip about 3 inches of insulation from the radiating element (C). (3) Cut enough wire to reach from the proposed location of the antenna to the radio set. Keep this line as short as possible, because excess length reduces the efficiency of the system. Tie a knot at each end to identify it as the "hot" lead. Remove insulation from the "hot" wire and tie it to the radiating element wire at insulator (C). Remove insulation from the other wire and attach it to the bare ground plane element wires at insulator (C). Tape all connections and do not allow the radiating element wire to touch the ground plane wires. (4) Attach a rope to the insulator on the free end of the radiating element and toss the rope over the branches of a tree. Pull the antenna as high as possible, keeping the lead in routed down through the triangle. Secure the rope to hold the antenna in place. (5) At the radio set, remove about 1 inch of insulation from each end of the wire. Connect the ends to the positive side of the cobra head connector. Be sure the connections are tight or secure. (6) Set up correct frequency, turn on the set, and proceed with communications.