anyone can help to tell the usage of the parallel Mline?

i am watching one ldmos transister data sheet, in the reference design, it use several short lines paralleling the main matching microstrip line, as shown red circles in the picture. what's the usage of these lines?

You need to do it in momentum.

thanks. is it used to optim EM field? i have simu by mometum, but EM field looked no change.

Probably they have been put for tuning, as they slightly increase the width of uStrip.

Mazz

yes exactly, it is used for on-board tuning, if expected performance is not reached they try to get by tuning using silver ribbon for example.

i see. thanks.

Added after 9 minutes:

is it possible to tune by simulation and how to do?
thanks.

You need to understand that let say you designed the layout but due to some defects either in PCB or components then you need to re-design the layout.
So, with this method you have the option to tweak the layout without doing re-simulations for the differed parameters as the design is close enough.

Q: is it possible to tune by simulation and how to do?
you can do it by placing a patch over these fractal parts.

thanks a lot.