Figure 3-8. Required Signal Level.

TM 11-5985-379-14&P

Required Signal Level.

Figure 3-8.

F i g u r e 3-9. Required Antenna Gain.

the dipole elements at a height of 15 feet. The

additional advantage of the sloping dipole con-

coaxial mast consists of eight identical sections,

f i g u r a t i o n is the vertically polarized component

(a figure eight-type radiation pattern) produced at

a n d i s c o n s t r u c t e d o f a l u m i n u m . T h e inner

the low frequencies that permits compatibility with

c o n d u c t o r of the coaxial mast is held concen-

trically within the outer conductor with a poly-

whip antennas where propagation conditions per-

u r e t h a n e f o a m . B a y o n e t - t y p e joints allow the

mit.

mast sections to be joined together quickly and

In order to provide an acceptable impedance to the

positively.

tuner of the AN/PRC-47, it is necessary to make

the sloping dipole fat. This is done by using two

T h e dipole radiating elements consist of four

wires positioned at right angles to one another.

wires for each half of the dipole. The four wires

They slope down to the earth and are made of

are equally spaced about the mast and serve as

flexible phosphor bronze wire with short lengths

guys as well as radiators.

of nylon rope attached to the ends through insula-

tors. Two of the elements are connected to the

Figure 3-11 shows the AS-2259 antenna (Collins

inner conductor of the coaxial mast and the other

637K-1) and depicts the design of the mast,

two are connected to the outer conductor.

f e e d , insulators, a n d ground stakes. The mast

a l s o serves as the transmission line, feeding

3-8