User Manual

MPR/MIB User’s Manual
Wireless Sensor Networks
Doc. # 7430-0021-06 Rev. A Page 30
8 ANTENNAS
8.1 Radio/Antenna Considerations
Care should be taken to provide an antenna that provides proper coverage for the environment
expected. Range and performance are strongly affected by choice of antenna and antenna
placement within the environment. In addition, care must be taken to ensure compliance with
FCC article 15 regulations for intentional radiators. Because of its small physical size, the usual
antenna chosen is a length of insulated wire one-quarter wavelength long for the frequency of
interest. This type of antenna is often called a monopole antenna, and its gain is ground plane
dependent.
Antenna lengths for the different radio frequencies are provided in Table 8-1.
Table 8-1. Antenna lengths for quarter wavelength whip antennas. The part number’s for the
connectorized antennas are listed.
Name Model
Whip Antenna Length
(inches)
Crossbow Part
No.
MICA2/MICA2DOT MPR400 (916 MHz) 3.2 8060-0011-01
MICA2/MICA2DOT
MPR410 (433 MHz) 6.8
8060-0011-02
MICA2/MICA2DOT MPR420 (315 MHz) 9.4 8060-0011-03
MICAZ MPR2400 (2400 MHz) 1.2 8060-0011-04
8.2 Connectors for the MICA2 and MICAz and Whip Antennas
The MICA2 and MICAz have an MMCX connector for attaching an external antenna. These
mating connectors can be purchased from Digi-Key. There are two manufacturers—Johnson
Components and Hirose Electric Ltd. The mating connectors come in straight and right angle.
They also support two different standard varieties of Coaxial cable—RG178 /U and RG 316/U.
There are also other vendors who sell MMCX to SMA conversion cables.
Table 8-2. Johnson Components’ MMCX mating connectors*
Type Coax Digi-Key PN Johnson PN
Straight Plug RG178/U J589-ND 135-3402-001
Straight Plug RG316/U J590-ND 135-3403-001
Right Angle RG178/U J593-ND 135-3402-101
Right Angle RG316/U J594-ND 135-3403-101
Right Angle RG 316 DS J595-ND 135-3404-101
*
These connectors require the following hand crimp and die set (Digi-Key part # / Johnson part #):
a) Hand crimp (J572-ND / 140-0000-952), b) Die (JD604-ND / 140-0000-953).
Table 8-3. Hirose MMCX connectors.
Type Coax Digi-Key PN Hirose PN
Straight Plug RG178/U H3224-ND MMCX-J-178B/U