Here we illustrate how to construct a Series-Shunt SPDT switch. Only in the transmit state we have to apply biasing, and both diodes are forward biased. D1 is a low impedance TX to Antenna. D2 is a high impedance at the antenna due to the ¼ length section. In the receive state both diodes are reversed biased, open, no current consumption during receive mode! One drawback, just as in previous example, is that it’s frequency dependent due to ¼ length section.