RL to VSWR tollerance converion

[disisku_22]

Hi
How to express RL(return loss) tolerances of +/-3 dB in VSWR. if i have 3dB RL tolerance then what should be the VSWR tolerance.

 

[albbg]

For sake of simplicity let's call V=VSWR, then:

RL=-20*Log[(V-1)/(V+1)], solving with respect to V:

V=[1+\[{ 10}^{(-RL/20}\]]/[1-\[{ 10}^{(-RL/20}\]]

then if you have a tolerance of "x" dB, then:

V(x)={1+\[{ 10}^{[(-RL+x)/20]}\]}/{1-\[{ 10}^{[(-RL+x)/20]}\]}

 

[disisku_22]

HI Albbg,
thanks.. but the tolerance varies depending on the RL. for example for 10dB RL as per above calculation VSWR tolerance is +/-0.5188 for +/-3dB RL tolerance, and same for 6dB RL the VSWR tolerances is +/- 1.8741. is there any relation ship between RL and VSWR for the tolerance.

 

[albbg]

HI Albbg,
thanks.. but the tolerance varies depending on the RL.

Yes, because dB is a relative measurement.
Unfortunately you cannot eliminate the tolerance in dB from the value of RL.