SITUATIONAL EXAMPLES.

TM 11-5820-919-12

early night but if sunspot conditions are poor. It may not

A2-24. Scenario (Figure A2-6). Your squad must set

be usable at all. This band is suitable for short range

tip an observation post (OP) as part of a road

(less than 10 miles) surface wave communication using

surveillance team. You are required to check in with

a whip antenna.

your headquarters (50 miles east) once every hour. your

OP is in a mountainous region and a large mountain is

A2-17. 25 thru 30 MHz. This band is useful as a very

located between you and your head(quarters (see fig

short range (several thousand miles) communications

A2-6). Your frequency possibilities) are the same as in

during good propagation condition It is generally

situation 1

unusable for intermediate range communication.

A2-25. Recommendation. Your OP is selected to

A2-18. SITUATIONAL EXAMPLES.

give you a clear view of the area while camouflaging your

position with the mountain as a background. Your radio

location is selected to provide a clear path to your

A2-19. The following examples demonstrate several

headquarters while shielding your transmissions from

different situations that might occur when attempting to

the enemy to reduce the possibility of being located with

establish a com munications link These examples will

radio direction finding equipment. Because you will be

help clarify the information on optimizing communication

maintaining a fixed location for an extended period of

time, you may use any antenna you wish. The best

A2-20. SITUATION 1.

choice would be the N_ antenna. Your headquarters is

only 50 miles east, however there is a large mountain

A2-21. Scenario. You are under enemy fire and cannot

blocking direct waves. The NVIS, with a very high angle

move without great risk. It is 1400 hours local time and

of radiation, will bounce off the ionosphere and over the

you are and you are trying to contact your Tactical

mountain Your transmissions might be copied b) the

Operation Center (10 miles south) to request air support.

enemy but your shielded location will minimize the

Your available frequencies are 2.138, 5.672, 9.193,

chances of being located. As the day progresses, you

11.272 and 16.385 MHz.

will want to change frequency in order to optimize

communications. The following recommendation should

A2-22. Recommendation. The tactical situation only

ensure constant communications.

permits the use of the w hip antenna. Since the station

with whom you want to communicate is only 10 miles

0001 to 0500 (dawn)

2.138 or 5.672 M}z

south . the whip antenna will be adequate. Considering

0500 to 1200

5.672 or 9.913 MHz

this to be short range surface w2ave, the best frequency

1200 to 2000 (dusk)

9.913 or 11.7211liz

selection would be a high one, in this case either 16.385

2000 to 2400

5 672 or 9.913 MHz

or 11.272

A2-23. SITUATION 2.

A2-4