Technical information
Table Of Contents
- GoMobile Cover
- SGC – The SSB People
- Go Mobile at 500 Watts
- T a b l e o f C o n t e n t s
- I n t r o d u c t i o n
- C h a p t e r 1 C h a n g e s i n M o b i l e R a d i o
- C h a p t e r 2 O r i e n t i n g Y o u r s e l f t o 5 0 0 W a t t s
- C h a p t e r 3 DCP o w e r S u p p l y S y s t e m f o r a M o b i l e I n s t a l l a t i o n
- C h a p t e r 4 A n t e n n a s a n d G r o u n d s
- C h a p t e r 5 N o i s e S u p p r e s s i o n a n d S h o c k -M o u n t i n g
- C h a p t e r 6 I n s t a l l a t i o n P r o c e d u r e s
- C h a p t e r 7 I n s t a l l a t i o n V a r i a b l e s
- C h a p t e r 8 G o i n g M o b i l e a t 1 5 0 W a t t s
- Appendix A — QMS S y s t e m
- A p p e n d i x B — S e l e c t i o n o f E q u i p m e n t
- A p p e n d i x C — T e s t D a t a
- It all Adds Up
Antennas and Grounds
Antennas for HF Mobile Installations
An antenna does not have to be a physical quarter wave-
length in order to work efficiently: shortened antennas can
be used. But when an antenna is less than a physical quarter
wavelength, it has less efficiency than a larger antenna. Use
of a high performance antenna coupler, such as the SG-235,
will improve antenna performance dramatically.
Short antennas represent some compromise. However, they
can give good performance, especially in applications such as
mobile HF work.
The standard whip antenna used in the HF environment has
a brief but interesting history related to the Citizen’s Band
radio craze, which swept the United States in the 1970’s. The
“generic” 108 inch long stainless steel whip, while it could be
mounted in such a way as to operate at 27 MHz without any
coils, traps, or matching network, is not generally well built
and may fail when used in commercial service because of its
poor base insulation and its lack of a shock-absorbing base:
it whips around.
Single frequency antennas. Single element commercial
heavy duty antennas such as those made by Hustler are a
step in the right direction for lower frequency HF work.
Although some companies still sell 108” stainless steel whip-
based products, the professional HF person will always
choose a center or top loaded whip antenna if a single fre-
quency is to be used.
Multiple frequency antennas. When a series of frequen-
cies across the spectrum is to be used, the professional
answer is either to put up with changing loading coils or to
put in a continuously loaded helically-wound antenna. This
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© 1997 SGC Inc.
SGC Inc. SGC Building, 13737 S.E. 26th St. Bellevue, WA. 98005 USA
P.O.Box 3526, 98009 Fax: 425-746-6384 or 746-7173 Tel: 425- 746-6310 or 1-800-259 7331
E-mail: SGCMKTG@aol.com Website: http://www.sgcworld.com
Chapter 4