harkonnen
Member level 4
Hi,
Some Cell-Phones (N0kia for example) have a connector on the back side of the cell-phone that can be used for an external antenna in a car for example.
But I am wondering, how is the RF diverted from the Power-AMP/LNA to the connector? If you connect a 50OHM line to the connector, your internal antenna is still connected. And external and internal antenna are then in parallel and thus not 50OHM.
I can't imagine that they use a SOI-Silicon or PHEMT switch inside since that needs extra board space and is expensive.
So, how do they match both the antennas with the external one connected and disconnected without having significant losses?
Some Cell-Phones (N0kia for example) have a connector on the back side of the cell-phone that can be used for an external antenna in a car for example.
But I am wondering, how is the RF diverted from the Power-AMP/LNA to the connector? If you connect a 50OHM line to the connector, your internal antenna is still connected. And external and internal antenna are then in parallel and thus not 50OHM.
I can't imagine that they use a SOI-Silicon or PHEMT switch inside since that needs extra board space and is expensive.
So, how do they match both the antennas with the external one connected and disconnected without having significant losses?