Avionics News November 2014 - 46

ANTENNA TECH

Continued from page 45

makes the antenna system much more important." Shrinking
frequency spacing is another challenge, as are systems like
Iridium and Inmarsat that operate on adjacent frequencies.
These antennas are engineered for a specific GPS or TCAS
systems, and their optimum performance starts with the
antenna's location. Deriving these locations is part of the
FAA certification testing, and it's why Garmin's test aircraft
"look like porcupines," Stone said. To the greatest extent
possible, an antenna must have an unimpeded line-ofsight to its intended source or station. "To make life more
challenging, you want each antenna optimally located, with
a minimum distance between them so they can cohabitate
happily," Stone said. Location and separation requirements
"can be at odds with each other, especially on a small
airplane or helicopter." The installation instructions include
"good, better and best locations because we know that the
optimal location is not always available."
The actual installation is equally important. "Poor

bonding between the antenna and its ground plane can
lead to odd problems," Stone said. "Depending on how
it degrades, it can be highly directional; it will work well
off the right wing but not the left." The radio can be the
problem, but troubleshooting should begin with the
antenna and its cables. The connections should be clean
and tight, with the proper resistance between the antenna
and ground plane, and the cables free from chafing. Garmin
offers specific troubleshooting tools for TCAS and the use of
diagnostic equipment to root out problems.
Cables are critically important, especially with low-signal
systems like GPS. Teflon-jacketed, double-shielded RG-400
is what most manufacturers recommend. And keeping the
distance this cable runs to the antenna is another factor in
the antenna challenge. If troubleshooting reveals no source of
the problem, and a length of RG-58 runs to another antenna,
perhaps its single-shielding is where the leak resides.
GPS interference seems to be a common troubleshooting
challenge today, according to Scott Cole, shop manager for
Cincinnati Avionics in Batavia, Ohio. Troubleshooting Garmin
units starts on the unit's signal strength page. "We know the

Do you have
unused
equipment
gathering
dust?
List your equipment for sale on the AEA database,

For more information, visit www.aea.net/eedirect, or
call Aaron Ward at 816-347-8400
46

avionics news

*

november

2014


http://www.aea.net/eedirect

Avionics News November 2014

Table of Contents for the Digital Edition of Avionics News November 2014

Point of Communication
AEA Now
The View from Washington
International News and Regulatory Updates
Shifting redundancy gears
Member Profile
AEA Rate & Labor Survey
A Conversation With...
Member Profile
Real-world Avionics
Antenna Tech
Aviation Aces
Business Basics
Before & After
Meet the AEA board of directors
Avionics technician certifications
Legal Ease
Marketing Report Card
What's New
Marketplace Classifieds
Avionics News November 2014 - Intro
Avionics News November 2014 - Cover1
Avionics News November 2014 - Cover2
Avionics News November 2014 - 1
Avionics News November 2014 - 2
Avionics News November 2014 - 3
Avionics News November 2014 - Point of Communication
Avionics News November 2014 - 5
Avionics News November 2014 - AEA Now
Avionics News November 2014 - 7
Avionics News November 2014 - 8
Avionics News November 2014 - 9
Avionics News November 2014 - 10
Avionics News November 2014 - 11
Avionics News November 2014 - 12
Avionics News November 2014 - 13
Avionics News November 2014 - The View from Washington
Avionics News November 2014 - 15
Avionics News November 2014 - International News and Regulatory Updates
Avionics News November 2014 - 17
Avionics News November 2014 - 18
Avionics News November 2014 - 19
Avionics News November 2014 - Shifting redundancy gears
Avionics News November 2014 - 21
Avionics News November 2014 - 22
Avionics News November 2014 - 23
Avionics News November 2014 - Member Profile
Avionics News November 2014 - 25
Avionics News November 2014 - 26
Avionics News November 2014 - 27
Avionics News November 2014 - AEA Rate & Labor Survey
Avionics News November 2014 - 29
Avionics News November 2014 - 30
Avionics News November 2014 - 31
Avionics News November 2014 - 32
Avionics News November 2014 - 33
Avionics News November 2014 - A Conversation With...
Avionics News November 2014 - 35
Avionics News November 2014 - Member Profile
Avionics News November 2014 - 37
Avionics News November 2014 - 38
Avionics News November 2014 - 39
Avionics News November 2014 - Real-world Avionics
Avionics News November 2014 - 41
Avionics News November 2014 - 42
Avionics News November 2014 - 43
Avionics News November 2014 - Antenna Tech
Avionics News November 2014 - 45
Avionics News November 2014 - 46
Avionics News November 2014 - 47
Avionics News November 2014 - Aviation Aces
Avionics News November 2014 - 49
Avionics News November 2014 - Business Basics
Avionics News November 2014 - 51
Avionics News November 2014 - 52
Avionics News November 2014 - Before & After
Avionics News November 2014 - Meet the AEA board of directors
Avionics News November 2014 - 55
Avionics News November 2014 - 56
Avionics News November 2014 - 57
Avionics News November 2014 - Avionics technician certifications
Avionics News November 2014 - 59
Avionics News November 2014 - 60
Avionics News November 2014 - 61
Avionics News November 2014 - Legal Ease
Avionics News November 2014 - 63
Avionics News November 2014 - Marketing Report Card
Avionics News November 2014 - 65
Avionics News November 2014 - What's New
Avionics News November 2014 - 67
Avionics News November 2014 - 68
Avionics News November 2014 - 69
Avionics News November 2014 - 70
Avionics News November 2014 - Marketplace Classifieds
Avionics News November 2014 - 72
Avionics News November 2014 - Cover3
Avionics News November 2014 - Cover4
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