Antenna switch for Nokia MD59 and Nokia 620
This switch is targetted for fast switching of antenna between RX and TX up to 7W.
Power is limited by heat generated on PIN diodes. For higher power replace BA479 by
some others with much lower Rdson (BA682).
During transmit, both diodes are open by DC current (which is limited by R1). R1's calculated value is for 9V. Max. is 50mA, 40mA is used here.
Transmit signal is then routed through the LC filter to the antenna.
Diode D2 shorts the transmit signal which could eventually reach the receiver.
The diodes are closed (off) during receive, so the signal goes through LC filter to the receiver.
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