Figure 3-10. Typical Input Resistance in Ohms Compared to Power Lost in dB Versus Antenna Height.

TM 11-5985-379-14&P

Typical Input Resistance in Ohms Compared to Power Lost in dB

Figure 3-10.

Versus Antenna Height.

by the U. S. Marine Corps and Collins Radio Co.

A full-scale antenna was erected and antenna

c u r r e n t distributions were measured at a num-

at the Panama Canal Zone in the jungle environ-

ber of frequencies. Radiation patterns and antenna

m e n t . Five test sites, varying from 10 to 300

gains are computed from these currents to pro-

m i l e s from the main transmitting site, were

v i d e full-scale performance data. Field patterns

selected. Jungle canopy varied from 50 to approxi-

are provided at a number of frequencies (figures

mately 200 feet. Comparisons were made, using

3-12 through 3-19) followed by gain contours of

the 637K Antenna and a 15-foot whip antenna.

t h e antenna plotted on a general propagation

All the tests confirmed the superior performance

c h a r t (figure 3-10). As shown by the general

of the 637K on short-range circuits.

p r o p a g a t i o n c h a r t , t h e antenna provides good

gain on short paths varying from 0 to about 300

miles.

The performance of the 637K antenna was veri-

f i e d in December 1967. Tests were conducted

3-9