Operating instructions

Choosing a Ham Radio 21
scribed on the ARRL’s Technical Information Service (TIS) Web page or you can buy one
or any of several common variations; off-center-fed, multi-wire, and G5RV antennas are
popular. While a dipole’s gain is low, it’s efficient and hard to beat for the price. You’ll
need one or two supports (trees work well) at least 20 feet tall. Large-scale versions of the
Yagi beam antennas mentioned in the VHF/UHF section can be placed atop steel towers,
although this is not required to get started.
Vertical antennas are also popular, particularly where a horizontal
antenna may be difficult to put up, for portable use, and where a “low
profile” antenna will be more suitable. The simplest is a quarter-wave
vertical made of metal tubing and radial wires fanning out from the
base to act as a ground plane. To use it on several of the HF bands will
require an antenna tuner described in the next section. Multi-band ver-
ticals are constructed to operate on several bands without the antenna
tuner. Ground-independent verticals are available that operate without
the radial wires.
Mobile antennas for HF use come in two common styles; fixed-tuned
and tunable whips. A fixed-tuned whip is adjusted to present the proper
load to the transmitter on one band or over a portion of a band. You will
need one for each band you intend to use, but they are inexpensive. The
whips have a 3/8”-24 threaded base that screws in to the antenna mount
on the vehicle, similarly to what is shown in the VHF/UHF section. A
tunable whip with an internal coil (called a “screwdriver” antenna) can
vary its length continuously to tune up on nearly any HF frequency. A
controller is mounted in the vehicle. Only one tunable whip is required,
although they are much more expensive than the fixed-tune whips.
Mobile antennas can be mounted on the vehicle temporarily or
permanently. A permanent mount generally results in a better electri-
cal ground connection to the vehicle, which is important for the HF
antennas to work well. Temporary mounts, such as larger versions of
the VHF/UHF magnet or mag-mounts, are usable for most purposes
Figure10
Mast
15-30’
Steel
Tower
>30’
Trees >20’
HF vertical
20-30’
Dipole
Figure10–Youhavemanyantennaoptionstochoosefrom,dependingonyourbudgetand
howmuchspaceyouhaveavailable.
YagiBeam
TheHighSierraHS-1800isaso-
called“screwdriver”styleHFmobile
antennathatprovidescontinuous
coverageforallHFbands.