Bird Technologies 4308 - Manual (Page 17)

Power
Since there is a definite relationship between the standing wave ratio and the forward-
reflected power ratio, the forward and reflected powers may be read from the Thruline
Wattmeter and converted to VSWR. The charts are furnished in this Instruction Book.
Coupling Circuit
The coupling circuit which samples the travelling waves is in the Plug-In Element. The
circuitry of the element and its relationship to the other components of the Thruline
Wattmeter are illustrated in the schematic diagram, see figure 2.
Energy will be produced in the coupling circuit of the element by both mutual inductance
and capacitance from the two travelling RF waves in the line section. The inductive
RF Coaxial Line
XMTR
or
LOAD LOAD
or
XMTR
Directional Coupling
Detector Element
Diode
Meter
DC Contact
Circuit Board
Figure
2
Schematic
Diagram
Theory Of Operation
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