|
 |
Low-profile antenna for 868 MHz with high directivity ? - RF Cafe
Forums
|
| malvinas2
|
|
Post subject: Low-profile antenna for 868 MHz with high directivity
?
Posted: Thu Feb 09, 2006 5:26 am
|
|
|
|
|
Hello,
I'm searching for a low-profile antenne
for 868 MHz, which possesses high directivity.
At the moment I don't have any idea how
an antenna like this could be build. Normally if
you want an antenna with directivity in this frecuency
range, one would build something like a logarithmic
antenna with a reflector and so on (Yagi etc.).
But my antenna has to be nearly planar. Another
possibility to achieve high directivity would be
the use of an array, but for the frecuency required
that would be quite big....
'High directivity'
is not defined exactly until now, because I'm just
searching for ideas, anything better than isotropic
would be of help.
Any ideas ?
|
|
| |
|
 |
|
!AliG |
|
Post subject:
Posted: Mon Mar 27, 2006 5:52 pm
|
|
|
|
I think you are right guys!
:)
|
|
| |
|
|
|
|
fred47 |
|
Post subject: Directivity
Posted: Mon Mar 27, 2006 7:12 pm
|
|
| |
| General |
 |
Joined: Wed Feb 22, 2006
3:51 pm
Posts: 104 |
|
Hi!
You don't mention which is more important:
1. Transmission/reception from only one direction
(narrow beam width), or 2. The ability to null out
signals to/from one direction.
Also, what
size range is acceptable? Your post seems a bit
vague here.
Directivity is really only obtained
by multiple radiators (the array approach, which
can include driven and parasitic arrays) or by quasi-optical
methods (parabolic dishes, lenses, etc.)
Good Luck!
Fred
|
|
| |
|
|
|
|
nubbage |
|
Post subject: Low Profile Antenna for 868MHz
Posted: Wed Mar 29, 2006 4:58 am
|
|
| |
| General |
 |
Joined: Fri Feb 17, 2006
12:07 pm
Posts: 218
Location: London UK
|
|
Other info missing: do you wish to design the system
or not?
If you wish to design it:
Using a
corporate strip-line array of full-wavelength (in
the dielectric) suggests an array of 4 full-wave
dipoles would measure about 30cm high by 20cm wide
for horizontal polar (or the other way round for
vertical polarization), and would give a gain of
about 12dBi
The dipoles are fed through 3dB
strip-line T junction matched splitters
if
you wish to purchase
Some companies manufacture
such antennas as flat panel types for this part
of the radio spectrum
Trev
|
|
Posted 11/12/2012
|
|
|
|
|
