Microwave SPDT help !!!

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yyman

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Hello EveryOne !!!
I'm simulating with ansoft designer V2 circuit simulator, a switched line phase shifter ( a very basical model ).This is the scheme :


the problem is :

SPDTs has v1=2V and V2=4V.

When SPDTs switch on the upper line (Vctrl < v1 and Vctrl=0) the phase shifter doesn't work ! But if i set the SPDT Ron a very small value ( 1e-9 ) it works perfect !

When SPDTs switch on the lower line (Vctrl > v2 and Vctrl=5V) the phase shifter doesn't work ! with lower (1e9) Ron doesn't work. With Ron equal to the Zo of the TxLine (50Ohm) it has a good S11 (measured in dB) and a very bad S21 (-144dB o.o).

How can i fix the problems ? Please, i have to write a thesis
 

A realistic Ron for a good electronic RF switch would be e.g. 1 ohm (0.17 dB loss).
 

Yep, i know it But it doesn't work aniway !!! However,i've solved it by replacing SPDTs with SPST
 

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