Specifications

3.3 Hardware Selection: The signal attenuation block shown in the above section was
implemented by using fixed value attenuators, as well as a step attenuator. The set of fixed
attenuators were procured from the Electrical and Computer Engineering Department RF lab.
The attenuators are fixed N-type attenuators from Weinschel Engineering. Not all of the
attenuators were rated for use at this frequency (5.8GHz) so they had to be calibrated by using
the network analyzer located in the Telecommunications lab in the ECE department. The fixed
attenuators were labeled with the value of attenuation that was measured at the desired frequency
of interest (5.8GHz). In addition a variable attenuator (HP 8494B) is also used with values
between 0 and 11 dB in 1 dB steps. This device is rated for use up to 18GHz. The operation of
the step attenuator was verified to be within 0.3 dB of the displayed value throughout its range,
by using the network analyzer. This configuration provided attenuation between 106 and 56 db,
corresponding to a maximum range of 113 miles under free space propagation conditions with
28dBi antennas, -86dbm receive sensitivity and 20dbm of transmit power.
The test bed allows for easy adjustment of the amount of additive noise induced into the system
by using a wide band calibrated noise source that is on loan from The Spectrum Research Lab
located at MSU. The noise source is a Noise Com NC6000 series broadband white noise source
with a built in step attenuator.
For doing high frequency radio testing it is necessary to have very high quality cables with both
low insertion loss and high isolation. The cables that were used for this project are manufactured
by Easy Form Cable Corporation and are excellent for these criteria. They are a flexible cable,
which is beneficial since several different configurations will need to be used. Rigid cables can
meet the technical demands, but are more difficult to work with. Model EZ flex 402 cable was
selected to meet all of the given requirements. A 2-way splitter and a 4-way splitter were
procured from Mini-Circuits and are specified to work at 5.8 GHz.
The radio terminals and transceivers are manufactured by Redline Communications. The
complete system is referred to as the AN-50 radio. The main components of the radio are the
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