5-GHz Antennas
Although most indoor 5-GHz products use permanently attached
antennas, there is a big push to move 5 Ghz to the bands permitting external
antennas. Presently, only a few antennas are available for the 5-GHz WLAN
products, and many of them are similar to those found in 2.4 GHz. As a
comparison, a 5-GHz 28-dBi parabolic dish is shown in Figure B-12. This particular antenna, from Maxrad, is
about the same physical size as the 21-dBi 2.4-GHz dish antenna. Notice,
however, that the gain is quite a bit higher for the same size, and the beam
width is drastically reduced (12 versus 4 degrees). This will continue to be the
case for 5-GHz antennas. For similar-gain antennas, a 5-GHz antenna will be
approximately half the physical size.
Table B-10 lists the
specifications for a high-gain (28-dBi) 5-GHz dish antenna.
Table B-10. 28-dBi 5-GHz Antenna
Specifications
|
Parameter |
Specification |
|
Frequency range |
5.7255.825 GHz |
|
VSWR |
1.5:1 nominal |
|
Gain |
28 dBi |
|
Polarization |
Vertical or horizontal |
|
Azimuth (3-dB BW) |
4.75 degrees |
|
Elevation (3 dB BW) |
4.75 degrees |
|
Maximum power |
4 watts |
|
Temperature (operating) |
30C min, +60C max |
|
Mounting |
1.52.5" mast mount |
|
Wind speed (operational) |
100 mph |
|
Wind speed (survival) |
125 mph |
|
Dimensions |
25" diameter |
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