question about airbridge

[danda821]

HI,

Can anyone tell me what is the use of airbrige? I have a CPW structure, the two end ground need to be connected by airbridge. Should it be connected by very narrow wire or wide wire? Thank you.

 

[jian]

Hi, danda821:

A multiple (more than 2) conductor TLN has more than 1 propagation mode without cut-off frequency. For CPW, the regular mode is (-, +, -) mode. However, you may excite the 2nd no cut-off mode (-, 0, +) mode. The airbridge connecting the 2 outer metals is to suppress the 2nd no cut-off mode. I believe the size of the airbridge may not be very critical normally. Certainly, it is too big, it may disturb the 1st mode of the TLN. Best regards.