Home |
Search |
Today's Posts |
#1
|
|||
|
|||
power formula for vswr?
If I know only the power in dbm is there a formula to arrive at
vswr without conversion first to watts or volts? outbound = +63dbm (2kw) reflected = +36dbm (4w) This is a waveguide system with a dummyload connected in the event the numbers seem improper. I would like to use the formula when we connect the real antenna. |
#2
|
|||
|
|||
power formula for vswr?
Gudmundur wrote:
If I know only the power in dbm is there a formula to arrive at vswr without conversion first to watts or volts? outbound = +63dbm (2kw) reflected = +36dbm (4w) Take the formula for calculating vswr from P in watts, previously converting the dBm into W. You'll get the following vswr=(1+10^(0.5*(Pout-Pref)))/(1-10^(0.5*(Pout-Pref))). Regards, Paweł Stobiński, SQ9NRY |
#3
|
|||
|
|||
power formula for vswr?
Paweł Stobiński wrote:
Gudmundur wrote: If I know only the power in dbm is there a formula to arrive at vswr without conversion first to watts or volts? outbound = +63dbm (2kw) reflected = +36dbm (4w) Take the formula for calculating vswr from P in watts, previously converting the dBm into W. You'll get the following vswr=(1+10^(0.5*(Pout-Pref)))/(1-10^(0.5*(Pout-Pref))). Regards, Paweł Stobiński, SQ9NRY SWR = -1? |
#4
|
|||
|
|||
power formula for vswr?
John - KD5YI wrote:
SWR = -1? Right, a little oversight. Swap Pout for Pref. Regards, Paweł Stobiński, SQ9NRY |
#5
|
|||
|
|||
power formula for vswr?
Sort of ...
The Return Loss is 63dBm - 36dBm = 27dB (that's very good!) Converting to reflection coefficient, Gamma = 10^(-27dB/20) = 0.0447 Then, VSWR = (Gamma + 1)/(Gamma-1) = 1.09 : 1 No volts or watts but, to be honest, Gamma is a voltage ratio ... :-) Hope that helped, Darrell ... "Gudmundur" wrote in message ... If I know only the power in dbm is there a formula to arrive at vswr without conversion first to watts or volts? outbound = +63dbm (2kw) reflected = +36dbm (4w) This is a waveguide system with a dummyload connected in the event the numbers seem improper. I would like to use the formula when we connect the real antenna. |
Reply |
Thread Tools | Search this Thread |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Forum | |||
Narrow lobe of a yagi | Antenna | |||
power output formula | Homebrew | |||
Power companies speading lies on BPL | General | |||
More power questions | General | |||
How was antenna formula for uV/Meter Derived? | Antenna |