Home |
Search |
Today's Posts |
#11
![]() |
|||
|
|||
![]()
JB wrote:
If you use the (Z02-Z01)/(Z02+Z01) for the reflection coefficient, Fine! But the line must be properly terminated resistively. Great for discussion but real world gets complicated fast. As soon as the load gets reactive, the phase between the voltage and current are different and the length of the coax and it's velocity factor now contribute unless it is really short compared with the wavelength. You need to wade through the math. No matter what the phase, the Bird directional wattmeter reads the forward or reflected power referenced to its 50 ohm Thruline plus or minus 5%. If that were not true, the Bird directional wattmeter would not meet its published specifications. The phase is taken care of when the sampled voltage and sampled current are added for forward power or subtracted for reflected power. Now tell me the truth, if the SWR is above 1.2:1, does that mean the radio is making more power? I certainly hope that is a rhetorical question. In a matched system, the reflected power is part of the forward power. In a matched system, the reflected power is redistributed back toward the load and becomes a percentage of the forward power. Source Power = Forward Power - Reflected Power = Load Power If the SWR is not 1:1, the forward power must necessarily be greater than the source power. Maybe the following web pages will help: http://www.mellesgriot.com/products/optics/oc_2_1.htm "Clearly, if the wavelength of the incident light and the thickness of the film are such that a phase difference exists between reflections of p, then reflected wavefronts interfere destructively, and overall reflected intensity is a minimum. If the two reflections are of equal amplitude, then this amplitude (and hence intensity) minimum will be zero." (Referring to 1/4 wavelength thin films.) "In the absence of absorption or scatter, the principle of conservation of energy indicates all 'lost' reflected intensity will appear as enhanced intensity in the transmitted beam. The sum of the reflected and transmitted beam intensities is always equal to the incident intensity. This important fact has been confirmed experimentally." http://micro.magnet.fsu.edu/primer/j...ons/index.html "... when two waves of equal amplitude and wavelength that are 180-degrees ... out of phase with each other meet, they are not actually annihilated, ... All of the photon energy present in these waves must somehow be recovered or redistributed in a new direction, according to the law of energy conservation ... Instead, upon meeting, the photons are redistributed to regions that permit constructive interference, so the effect should be considered as a redistribution of light waves and photon energy rather than the spontaneous construction or destruction of light." -- 73, Cecil http://www.w5dxp.com "According to the general theory of relativity, space without ether is unthinkable." Albert Einstein |
Thread Tools | Search this Thread |
Display Modes | |
|
|
![]() |
||||
Thread | Forum | |||
Lens' observations ... | Policy | |||
IMD observations | Shortwave | |||
Initial Observations on the Eton S350DL and the Kaito WRX911 | Shortwave | |||
Observations and predictions on the NPRM | Policy | |||
WGN 720 Silent Period-Observations | Shortwave |