On 7/13/21 9:19 AM, Jim Lux wrote:
On 7/13/21 7:29 AM, stephenmahrer@... wrote:
Simple 75 to 50 and 50 to 75 Ohm minimum loss matching pads.
These are lossy by nature, about 5.7dB.
Best!
Steve Mahrer
Bear in mind that a resistive pad might provide "minimum loss" but is not an "impedance transformer" for making measurements.
That is, it's not the same as changing the reference impedance on your plots - for an obvious case, a 50 ohm load with a 75 system is a S11 = -14dB (VSWR 1.5:1), but if you look at a 50 ohm load through a MLP, you see a S11 of -25dB and a VSWR of 1.1
????Series???? Shunt???? Impedance seen by Test???? gamma 75 gamma 50???? VSWR 75 VSWR 50
????|S11| (75)???? |S11| (50)
Load???? 43.3333???? 86.6666
ok that's ugly.. I attach the xls
But the point is that a MLP presents a good match at the design impedance to both sides, it's not like a 75:50 ohm transformer.
