microstrip quarter-wave length transformer

in the attached paper, the frequency is 6GHz,but the transformer is 4.922mm long,not lambda/4 at all. why is that?
And in caculating the resistance Zin of patch, I get G1=0.0025, G12=0.0042,it seems not a right result!

thanks!

Electrical length of a transmission line may be different than the Physical length.

well i think quarter wave transformer length is close to lambda/4.

as the substrate permitivity is 4.4 so the guided wavelength is 24mm approx.

so lambda/4=5.9

so the optmized length for this design may be 4.9

i hope this answers your question

Dear ljx1067

you need to know that in papers the author not allays give you the exact
design. he gives you the start of his work and the end of it and then let you to figure what is missing between.
about the λ/4 the coupling between the patch and transformer also radiation from patch and thin line
cause to the change in dimantion.

pl