"Cecil Moore" wrote in message
...
shuisheng wrote:
I am new to antenna field. Anyboday can explain to me what is low
profile antenna? Many thanks.

An underground buried antenna would be an example of a
very low-profile antenna. Virtually invisible antennas
are another example. Disguised antennas (e.g. flagpoles)
are another example. Attic antennas are another example.
In general, low-profile antennas are inferior in performance
to high-profile (extremely visible) antennas.
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73, Cecil http://www.qsl.net/w5dxp

Sorry, absolute blx. You are getting confused with a covert antenna.

A low profile antenna is one that is designed not to stick up when
vertically polarised, and may at the same time be not visually
intrusive.

They are most often found (and visible) on the roof of security vans
or buses, and look like a small flat-ish upturned dish - for UK
hi-band (170MHz) being about 18" across and about 2-3" high. In most
applications they are omnidirectional and vertically polarised.
Technically they are a slot antenna - a Google search will explain how
they work. They have the advantage that the metal fixing base will act
as a ground plane so they can be fitted on fibre-glass bodies without
worry. They are popular on buses as they don't get pulled off by the
vehicle wash.


--
Woody

harrogate2 at ntlworld dot com