Ground Plane Size, Resonant Frequency and Soldering Notes for GPS Patch Antennas
1307039
1307039
Application Note
The Choice of Polarization 鈥?Indoor Picocell
Antennas
Linear Polarization
Unlike many outdoor environments, where direct line-of-sight
between a transmitter and receiver allows reasonably unobstructed
reception, indoor environments contain objects between the trans-
mit and receive antennas. A linearly transmitted signal (either
T
vertical
vertical or horizontal) can reflect off of walls and furniture, no
longer traveling in a straight line. This 鈥榤ulti-path鈥?effect causes
signal degradation and even cancellation where there are many
reflective surfaces inside a building.
R
multi-path
horizontal
Reflective surface - angle of arrival
Circular Polarization
Circular polarization can significantly reduce multi-path effects
in indoor environments. A circularly polarized signal is com-
prised of two orthogonal (right-angle) linear signals separated 90
degrees in electrical phase. (The vertical and horizontally polar-
ized signals are spatially 90 degrees apart, with a 90 degree time
delay built into the antenna design.)
Time
vertical
Because different linear polarizations reflect and penetrate sur-
faces differently depending on the angle of arrival and material
type, the most effective way to reach inside buildings is to use a
circularly polarized antenna. The circularly polarized wave, as
shown above, contains all the senses of linear polarization,
(where vertical and horizontally polarized signals have maxi-
mum reflectivity off of a given surface at different angles), and
will not cancel each other out. This allows for more continuous
coverage in indoor environments than a purely linear polarized
signal, and significantly increases the probability of maintaining
the link.
A combination of linear vertical polarization and circular polar-
ization is also acceptable in designing indoor wireless networks,
depending upon the materials making up the reflective surfaces.
At 7 dBi and 7 dBic gain, our micropicocell antennas provide
continuous and efficient coverage for any indoor system.
90潞
horizontal
V2.00
M/A-COM Division of AMP Incorporated
s
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Europe: Tel. +44 (1344) 869 595, Fax+44 (1344) 300 020
www.macom.com
AMP and Connecting at a Higher Level are trademarks.
Specifications subject to change without notice.
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