bidbirdlin
Newbie level 1
Hi,
I use SMA connector with RF Pin. The RF Pin is standing out of the internal cavity of the Enclosure and bond with Gold Ribbon on Microstripe Substrate.
Please refer to attachment for the structure. For this kind of connection, I didn't get very good Return Loss(-5dB) and Insertion Loss(-2dB). The reason might be just not 50ohm matching and the inductance of the gold riboon which make return worse. I can use quarter wave length of 50ohm Transmission line with some tuning to get at least 2:1(-10dB) Return Loss but this is not a perfect solution.
I have also calculated the lossless coaxial line impedance by the formula Zo=(60/√(Er))ln(b/a) which "b" is outer radius of Enclosure Wall and "a" is inner radius of RF Pin. If air is the insulating material between enclosure wall and RF pin, by using 15mil diameter RF pin I need 35mil diameter of Enclosure hole to produce 50ohm impedance.
I have created an enclosure with 30mil diameter hole to test previous theory but I didn't get good return loss either. Although I still can do some tuning on 50ohm T.L to get good return loss, this is still just a temporary solution.
I still hope I can get a better solution so I don't need to turn to get at least 2:1(-10dB) return loss. I am searching any solution and also see if there is any better SMA or other type or connector can be used for this kind of purpose. The connector is 90 degree to the surface of my circuit. Therefore I need
to find something can provide good 50 ohms matching between this two discontinuities.
Thank you for viewing my question.
I use SMA connector with RF Pin. The RF Pin is standing out of the internal cavity of the Enclosure and bond with Gold Ribbon on Microstripe Substrate.
Please refer to attachment for the structure. For this kind of connection, I didn't get very good Return Loss(-5dB) and Insertion Loss(-2dB). The reason might be just not 50ohm matching and the inductance of the gold riboon which make return worse. I can use quarter wave length of 50ohm Transmission line with some tuning to get at least 2:1(-10dB) Return Loss but this is not a perfect solution.
I have also calculated the lossless coaxial line impedance by the formula Zo=(60/√(Er))ln(b/a) which "b" is outer radius of Enclosure Wall and "a" is inner radius of RF Pin. If air is the insulating material between enclosure wall and RF pin, by using 15mil diameter RF pin I need 35mil diameter of Enclosure hole to produce 50ohm impedance.
I have created an enclosure with 30mil diameter hole to test previous theory but I didn't get good return loss either. Although I still can do some tuning on 50ohm T.L to get good return loss, this is still just a temporary solution.
I still hope I can get a better solution so I don't need to turn to get at least 2:1(-10dB) return loss. I am searching any solution and also see if there is any better SMA or other type or connector can be used for this kind of purpose. The connector is 90 degree to the surface of my circuit. Therefore I need
to find something can provide good 50 ohms matching between this two discontinuities.
Thank you for viewing my question.