TM-9-2350-275-BD

M113 FAMILY CARRIER, PERSONNEL SELF-PROPELLED FULL-TRACKED

TECHNICAL MANUAL; OPERATORS, ORGANIZATIONAL, DIRECT SUPPORT AND GENERAL SUPPORT MAINTENANCE; BATTLEFIELD DAMAGE ASSESSMENT AND REPAIR

TM-9-2350-275-BD - Page 128 of 223

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