| Home |
| Search |
| Today's Posts |
|
#11
March 14th 06, 11:54 PM
posted to rec.radio.amateur.antenna
|
|||
|
|||
Current through coils
Richard Harrison wrote:
Tom, W8JI wrote: "A traditional directional coupler works by comparing voltage across the line at any one point to current in the line at that same point." Almost. It compares a voltage sample to a current sample, both of which have been converted into d-c voltages. These have been carefully crafted to be exactly equal d-c voltages regardless of the power level in the line. I`m giving up on correcting line by line. Important fact is that a reflection reverses the phase between the voltage and current produced by a wave. So when the samples from the forward wave are siummed, their total is exactly 2x the value of either the voltage-derived sample or the current-derived sample. When the samples from the reflected wave are summed, being equal but opposite in polarity, they add to ZERO. Calibration is so the total produces the correct value on the power scale for the wave in the forward direction. To get the power in the reverse direction, the input and output are effectively exchanged so that the forward power indication cancels and the reverse power indication is produced by the sum of its voltage and current d-c sample outputs. Thank you for this concise summary. |
| Thread Tools | Search this Thread |
| Display Modes | |
|
|
Similar Threads
|
||||
| Thread | Forum | |||
| Current in Loading Coils | Antenna | |||
| FCC: Broadband Power Line Systems | Policy | |||
| FS: sma-to-bnc custom fit rubber covered antenna adapter | Scanner | |||
| Current in antenna loading coils controversy (*sigh*) | Antenna | |||
| Current in antenna loading coils controversy | Antenna | |||
Threaded Mode
