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ANTENNA SYSTEM
2001 NEW
■ Antenna for ship
Required antenna element length
Required antenna element length to achieve full per-
formance varies according to the lowest frequency:
The longer the antenna element, the better the an-
tenna efficiency.
Undesirable antenna element lengths
AVOID
multiples of
1
⁄2λ (half wavelength) for an-
tenna element lengths, since tuning becomes difficult.
L : Antenna element length to be avoided [m]
f : Operating frequency [MHz]
n : Natural number (n = 1, 2, 3, ...)
[Example]
At an operating frequency of 16 MHz, avoid the fol-
lowing antenna element lengths:
For example, if 15 m is selected for an antenna ele-
ment length, you have no problem in the 1.6–25 MHz
marine bands range.
NOTE: Keep antennas as far away from other objects
as possible, especially metal objects.
Insulator
Backstay operates as
a long-wire antenna.
Insulator
Whip antenna
L =
300
16
×
1
2
n
×
9.4, 18.8, ...
1 m
39 inches
L =
300
f
×
1
2
n
×
The lowest frequency Required antenna element length
1.6 MHz band 7 m; 23.0 feet or longer
4 MHz band 3 m; 9.8 feet or longer
AT-141_0.qxd 05.12.1 11:06 Page 1