LNA protection circuit via RF SPDT switch?

I'm working a small LNA and would like to protect it's input when the radio transmits (1W). Problem is the only voltage i have to work with is 3.3V when the LNA is on.
This rules out a reflective sPDT switch because its requires a steady voltage VDD and control Vds.

Any suggestions on what to place between the antenna and LNA input that would
essentially ground the LNA input when there is no voltage, and turn "on" completing the circuit (antenna to LNA) when 3.3V is present? Freq is 1.5GHz.

You can use an open λ/4 stub switched with a PIN diode (as in the picture).
The quarter wave stub is λ/4 at TX frequency. The length needs some tuning function of your PCB properties.

The PIN diode should be biased (R1) according to the available LNA_Vcc.

When the LNA_Vcc is 0V, the TL sees open circuit at one end, and shortens the TX leakage to the ground.

When the LNA_Vcc is ON, the TL sees short circuit at one end, and provides a through connection between inp and LNA_inp

Thanks, but my TX/RX freqs are too close together for that approach. appreciate any other suggestion.

Added after 51 minutes:

Could i simply use a PIN diode at the input of my LNA that will be biased when 3V is applied? When 0 volts will it seem like infinite resistance?

This will work for any TX/RX frequencies, even they are the same, because this is not a T/R switch. Is just a rejection of the TX leakage at the LNA input when the LNA is OFF.

You can use just a series PIN diode in front of the LNA biased during LNA_ON, and non-biased for LNA_OFF, but you get less isolation of the TX leakage than example using an open/short λ/4 stub.

The transmitter does not have a power supply? Why don't you have any DC power available when it is transmitting?

The circuit shown is a good one, but is not a SPDT. Can you use it? The only change I would make is some sort of resistor to ground to blead off any rectified current in the o.c. pin diode.