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A loop or track-style antenna is usually printed directly on the
PCB making it the most cost-effective of antenna styles. There
are many different styles and shapes of loops which can be
utilized, including spirals and rectangles. A loop has excellent
immunity to proximity detuning (i.e., a user’s body) and is
easily concealed inside products which have a plastic case.
Despite these advantages a loop is difficult to match and tune
without expensive RF test equipment. An improperly designed
loop will have a very high SWR and may induce harmonics. For
this reason a helical or whip style is usually a better choice for
applications requiring maximum range-performance. For
products where cost or size is critical, a designer will generally want to have a loop
professionally designed and optimized.
PARAMETER
LOOP
HELICAL
WHIP
Ultimate performance
●
●●
●●●
Ease of design setup
●
●●
●●●
Size
●●
●●●
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Immunity to proximity effects
●●●
●●
●
HP-II Range
(
open ground to similar antenna
)
400 ft.
600 ft.
1,000+ ft.
●
=FAIR
●●
=GOOD
●●●
=EXCELLENT
HP Antenna Selection Chart
Helical Style
A helical is a wire coil usually wound from steel, copper or
brass. This antenna is very efficient given its small size. The
helical is an excellent choice for products requiring good
range-performance and a concealed internal antenna
element. Care must be exercised in placement, however, as a
helical detunes badly when located in proximity with other
conductive objects. Because a helical has a high "Q" factor its
bandwidth is very narrow and inter-coil spacing has a
pronounced effect on antenna performance. For this reason it
is usually best to utilize a premade helical which has been
professionally optimized to achieve maximum performance.
Loop Style
