RF antenna lightning protection

[tarmogr]

Im designing a lightning protection circuit for GPS module that works off 3,3V and antenna line is used to feed antenna with 9V DC through bias tee.

I have a gass tube discharge(GDT) element in antenna cable that should take the voltage down to about 90V, but I need help designing the low voltage protection stage that I plan to place on the same board as GPS module

I have not found a good TVS that would suit for 1575 Mhz singnal since a typical capacitance of these things are in nanofarads, but for GPS signal <1pF is recommended.

Here are some sample schematics that I go by, but I dont get it why the inductor is needed in series with TVS or GDT?
Link Link

Is the purpose of these to maybe lessen the capacitance of TVS?
How can I calculate correct inductance values?

 

[Dan Mills]

@1.6GHz you should be able to contrive a simple shorted 1/4 wave stub as the DC injection choke, then cap, GDT and transorb the hell out of the DC end of the choke, that way the RF short circuit at the end of the stub is transformed to an open at the feedline at the operating frequency so the capacitance of the transorb on the DC side does not matter.

In fact a few such stubs along the line are an interesting possibility, take a 1/4 wave stub, short one end to the ground plane with a largeish cap, and place a transorb across the cap, the stub appears as a short circuit down near DC where the discharge energy is, so the transorb can work and appears as an open at resonance.

Low frequency energy picked up by the feedline will go straight thru the choke and be absorbed by the protection on the DC side.

1.6GHz is high enough that printing the 1/4 wave choke straight onto the PCB is practical.

Regards, Dan.

 

[tarmogr]

I made a circuit of what you suggested. The first image I reolaced the 1/4 wave stub with ESD low capacitance protection, that you can place directly to signal trace:


But what you proposed is if I would replace that ESD protection with schematic like this?


Is the scematic what you ment? Also I have some questions like If my transorb at DC side is "Peak pulse current (tp 10/1000us)=100A" (what does the to 10/1000 stand for?)

https://www.semtech.com/images/datasheet/lc01-6.pdf​

Then what should be the current rating of the coil? If nominal is 500mA then surge should be much more?