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5/25/2007
Document number: 060-FSA-ABQ-AAS-AGZ
Rev. 001
1. Passive
2. Amplified
3. Amplified - High Isolation
Passive Option:
In the Passive Configuration, the RF input from the antenna bypasses the amplification stages
and is passed directly to the input Wilkinson Splitter element. This splitter element divides the
RF signal evenly, resulting in 3dB (ideally) reduction in signal level at the output of each splitter.
The signal is then split again, resulting in four outputs, each output being 6dB (ideally) below the
input signal. In reality, since the Wilkinson Splitter elements are realized with non-ideal
components which have a finite Q, the signal reduction for each Wilkinson Splitter element is
approximately 4dB, resulting in an overall signal reduction through the splitters of approximately
8dB. When other losses are accounted for, such as losses in the RF connectors and the “Bias-
T’s”, the overall signal reduction through the passive configuration is approximately 9dB.
Amplified Option:
In the Amplified Configuration, the RF signal from the input is applied to two RF gain stages
prior to the Wilkinson Splitter elements. The first of these amplification stages provides
approximately 17dB of gain at a very low noise figure. The second stage provides additional
gain so as to ensure that the input port to any output port gain of the splitter is approximately
21dB.
Amplified – High Isolation Option:
In the Amplified – High Isolation Configuration, resistive, 50 Ohm signal attenuators are added
in the RF output paths to provide additional isolation between each RF port. This configuration
may be chosen if it is possible for spurious emissions from one GPS receiver on one port of the
splitter to cause interference with GPS receivers connected to other output ports. In the high
isolation configuration the input port to any output port gain of the splitter is approximately 10dB.
Termination of Unused Ports:
Note that in the Passive and Amplified (NON-High Isolation) configuration, all ports must be
terminated in 50 Ohms in order to ensure proper operation of the Wilkinson Splitter elements. If
all ports are not terminated properly, the S14WI input/output SWR and Gain/Loss may not meet
specifications.
In the Amplified-High Isolation configuration, the 50 Ohm signal attenuators provide substantial
isolation from open circuits on unterminated output ports. Consequently, RF outputs may be left
unterminated without adversely affecting the operation of the S14WI.
Bias-T’s:
GPS RF signal splitters are unique relative to other generic RF signal splitters in that they
typically operate in conjunction with an active GPS antenna (that is a GPS antenna that includes
an integrated Low Noise Amplifier). Consequently, a GPS RF signal splitter must have
provisions for managing the DC voltages to the active GPS antenna. These DC voltages are
typically applied to the center conductor of the RF coaxial cable which runs from the antenna
