es(source mismatch error): from directional coupler to port 1 and to the dut, there are transmissioin line, impedance mismatch, propagation delay. but viewing from the directional output port to port 1 and to the dut, we can simply regard this reflection back to dut as es. es is a reflection back to dut
et(tracking error): this is the reverse coupled port antenuation plus mismatch error between coupler and port 1, together with the cable attenuation, phase dealy on the extension cable to the dut.
using the equation, s11_actual = (s11_measured - ed)/[et + es*(s11_measured-ed) ]. we can substitude s11_actual by cal kit open and short reflection. cal kit open is s11_actual = 1, cal kit short is s11_actual = -1. so we can have the following:
s11_a_open = 1 = (measured_s11_open - ed)/[et + es*(measured_s11_open-ed) ] ...(a)
s11_a_short = -1 = (measured_s11_short - ed)/[et + es*(measured_s11_short-ed) ] ....(b)
s11_a_load = 0 = (measured_s11_load - ed)/[et + es*(measured_s11_load-ed) ] ....(c)
(measured_s11_open - ed) = [et + es*(measured_s11_open-ed) ] ....(d)
(ed - measured_s11_short) = [et + es*(measured_s11_short -ed)] ....(e)
ed = measured_s11_load ...(1)
(e) become
et = (ed - measured_s11_short) - es*(measured_s11_short -ed)
= (1 + es)*(ed - measured_s11_short) .....(f)
sub(f) into (d), we have
(measured_s11_open - ed) = (1+es)*(ed - measured_s11_short) - es*( ed -measured_s11_open)
= ed -measured_s11_short - es*measured_s11_short + es* measured_s11_open
= ed - measured_s11_short - es*(measured_s11_short - measured_s11_open)
so, we now have
es = (2*ed - measured_s11_open - measured_s11_short) / (measured_s11_short - measured_s11_open) ...(2)
similarly, we can get et, it is
et = 2*(measured_s11_open +ed)*(measured_s11_short +ed)/(measured_s11_short - measured_s11_open) ...(3)
以上是自己推演出来的,跟wanglie72兄贴的结果是一样的
