TM-9-2350-275-BD Battlefield Damage Assessment and Repair for M113 Family Download
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TM 9-2350-275-BD COMMUNICATIONS SYSTEM 11-21. GROUND PLANE FIELD EXPEDIENT ONE-QUARTER WAVE ANTENNA General Information This procedure gives instructions for construction of a one-quarter wave ground plane antenna which can be used for transmission and reception. This antenna has the capability of increasing the range of FM radios. Limitation ● Can only be used on a stationary vehicle and when a tree is available for suspension of the antenna Personnel/Time Required: ● 1 soldier ● 30 minutes Materials/Tools: ● Cable, l-roll, telephone, WD-1/TT ● Insulators (e.g., glass, plastic, leather, nylon, etc.) (Five required) ● Rope ● Sticks or branches, 3-foot length, (three required) Other Option: ● Repair broken metallic whip antenna. (Refer to para. 11-17.) ● Field expedient metallic whip antenna. (Refer to para. 11-18.) ● Field expedient replacement of fiberglass antenna. (Refer to para. 11-20.) ● For reception only, field expedient auxiliary antenna. (Refer to para. 11-19.) Procedural Steps: 1. Determine the length of wire needed for the radiating element of a one-quarter wave antenna using the following formula: Length (feet) . 234 divided by frequency (MEGAHERTz) or Length (meters) = 71.37 divided by frequency (MEGAHERTZ) Example- A radiating element for a frequency of 50 MHz L (feet) = 234 divided by 50 MHZ = 4.68 feet or L (meters) = 71.37 divided by 50 MHZ = 1.43 meters 11-22