Are vias needed with GCPW and clip SMA port?

Janny

In this AA Feko writeup the vias appear to connect CPW ground tracks to the lower ground plane, meaning the actual signal ground from feed is on the ground plane.

If we use PCB SMA edge port (coaxial connector) where the connector ground lugs are soldered to both the top CPW ground tracks and the lower ground plane, essentially electrically bonding all that copper together, then are vias even needed, and if so why?

Vias do add reactance, so are there any general rules for starting with standard GCPW design and then adding vias without impacting characteristic impedance, like where vias should be placed, etc?

AltAir reference: https://help.altair.com/2025/feko/topics/feko/user_guide/appendix/how_tos/feed_cpw/construct_cpw_feko_t.htm

Jaehoon

Dear Janny,

As shown in the picture (from internet) below, the vias should be needed to make sure the connection between two ground planes. (You might also find more example pictures from internet.)

Best regards,

Jaehoon