Radiation losses in Microstrip Lines

[Amr Wael]

Hello ,
After reading many papers about radiation losses in microstirp lines , 90% of them illustrate the effect mathematically and illustrate the relation between losses and the design parameters through equations only such as thickness , dielectric constant ,circuit geometry and high frequencies.
But I am trying to understand why the microstrip Line radiates in first place ?
What are the physical reasons behind this effect ? and what are the physical EM reasons that relate all those different parameters to radiation losses?
Thank you very much

 

[FvM]

Any open (unshielded) conductor geometry has a certain coupling to the far field and is respectively radiating. You could also ask, why does it radiate less than a dedicated antenna, what's the difference between a microstrip transmission line and a patch antenna?