How to match negative Zs with Smith Chart? (-28.385865049 - i70.62129951)

[Terminator3]

How to match negative Zs with Smith Chart? ( -28.526393888 + 70.854968742i)

I am using Smith v3.10. After calculating required Zs for transistor matching, i realized that Re part is -28, and can't be put into program.
How to solve this problem? Samples from my book have no such case.

_S11=PolarToRect(0.7,-64.8)
	_S11 = 0.298045504 - 0.633378937i

Gs=1/_S11
	Gs = 0.608256131 + 1.292610075i


Zs=50*(1+Gs)/(1-Gs)
	Zs = -28.526393888 + 70.854968742i


Gout=S22+(S12*S21)*Gs/(1-S11*Gs)
	Gout = 1.886478204 + 0.744136625i

Zout=50*(1+Gout)/(1-Gout)
	Zout = -116.175687126 + 55.549873949i

Abs(Gs)
	Ans = 1.428571429

Abs(Gout)
	Ans = 2.027939676

 

[flanello]

You can't have a negative real part.
What is the Gs value?

 

[mtwieg]

Sure it can have a negative real part, if it's an active network. But you can't match to it with a lossless network. You can either move Z into the RHP using series/shunt resistance, or change the transistor circuit to give a RHP Z.

 

[Terminator3]

Gs is Гs - source reflection coefficient
_S11 is S11 with a little smaller real part

- - - Updated - - -

Oh i see.

or change the transistor circuit to give a RHP Z

Does it mean something like changeing _S11 from (0.7, -64.8deg) to (1,-64.8deg), then real impedance part becomes zero?
I am learning an oscillator.