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what happens to reflected energy ?
On Sun, 6 Jun 2010 14:21:16 -0700 (PDT), Keith Dysart
wrote: The 100W forward and 50W reflected have no relation to actual powers From a current NARDA specification: GENERAL COUPLER OPERATION A coaxial directional coupler has the general appearance of a section of coaxial line, with the addition of a second parallel section of line and with one end terminated (see Figure 9). These two sections are known as the main and auxiliary lines. The two lines are internally separated from each other; the amount of spacing between lines determines the amount of RF energy that may be transferred from the main line to the auxiliary line. In operation, assume that energy is fed into port A of the main line. Most of this energy will appear at output port B of the main line. However, a fraction of this energy (determined by coupling value) will also appear at the coupled port C, of the auxiliary line. A dual-directional coaxial coupler, such as the reflectometer coupler, consists essentially of two single- ended couplers connected back-to-back. Perhaps the most important characteristic of the directional coupler (and the one from which its name originates) is its directivity. .... For reflectometry applications, the dual directional coupler, incorporating two auxiliary outputs, permits the simultaneous sampling of incident and reflected power. .... RF power applied to the load is reflected to some degree depending on load characteristics, thereby resulting in a voltage standing wave ratio (VSWR) which is reflected back to the main line output port. this reflected power is coupled out of the reflected output port at a level 10 dB down from the reflected power level at the load. 73's Richard Clark, KB7QHC |
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