Physical length calculation of RF tracks

Question

Hi, 
 In HMC457 datasheet Tl1 and TL2 lengths are mentioned as 0.017 and 0.08 inches respectively. Both are 50ohm lines. For achieving this we can adjust track width. The Transmission lines will act as inductors and form Tee- matching network. The values are given with respect to RO4350B. If I want to use ITERA MT 40, how the physical length will change? Whether electrical length will remain same or not?

enash · Answer

I would fabricate the traces to be 50 ohms in Itera MT40. and use the same physical length. I would not think of the TL1 and TL2 lines as inductors. Think of them instead as yielding a phase shift that is proportional to their length. - Eamon

enash · Answer

Yes, the dielectric constant does affect the speed of the signal on the line but if you do the equations, I think that you will find that the difference will be very slight for typical dielectric constants.

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Physical length calculation of RF tracks