Antenna System; Antenna For Ship; Antenna For Land Operation - Icom AT-140 Instruction Manual

1

ANTENNA SYSTEM

n Antenna for ship
Required antenna element length
Required antenna element length to achieve full per-
formance varies, according to the lowest frequency.
The lowest frequency
1.6 MHz band
4 MHz band
The longer the antenna element, the better the anten-
na efficiency.
Undesirable antenna element lengths
DO NOT
use an antenna element such as multi-
1 λ lengths (half wavelength), since tuning
ples of ⁄
2
becomes difficult.
L : Undesirable antenna element length [m]
f : Operating frequency [MHz]
n : Natural number (n = 1, 2, 3, ...)
300 1
L = × × n
f 2
[Example]
At an operating frequency of 16 MHz, avoid the fol-
lowing antenna element lengths:
300 1
×
× n
L =
16 2
1 m 39 inches
For example, if 15 m (49.2) feet is selected for an
antenna element length, you have no problem in the
1.6–25 MHz marine bands range.
n Antenna for land operation
In some countries, HF transceivers can be used
for land mobile operation. Ask your Icom Dealer for
details, since the radio law varies according to each
country.
For land mobile operation on 4 MHz or above, an
optional AH-2b
antenna element
AH-2b includes a sturdy tow hook mount system for
holding a 2.5 m (8.2 feet) stainless steel antenna ele-
ment plus all the necessary hardware.
1
Required antenna element length
7 m (23.0 feet) or longer
3 m (9.8 feet) or longer
9.4, 18.8, ...
is available. The
AH-2b
Insulator
Backstay operates as
a long wire antenna.
Insulator
NOTE: Keep antennas as far away from other
objects as possible, especially metal objects.
Refer to the AH-2b instruction manual for the AH-2b
and AT-140 installation to your vehicle. Ask your Icom
Dealer for details.
Connect a suitable antenna element for a base sta-
tion. To achieve full performance, refer to "Required
antenna element length" as described above.
Whip antenna