RF ESD protection

Hi Nicolas,

Your image didn't post. You will have to use the picture icon in the tool bar so we can see what you are referring to.

John

Ok thanks

https://www.u-blox.com/sites/default/files/products/documents/GPS-Antenna_AppNote_%28GPS-X-08014%29.pdf

page 20 FIG 21

Hi Nico,

You can calculate the impedance and just ensure it is significantly higher than 50 ohms, for the frequency that you're working at. However, the real-world inductor will also have capacitance. At the frequencies that device will operate at, you can't use any inductor. I think option 3 in the document will be easier. Also, there is further reasoning to support this and suggestions for option 3 here:

https://www.murata.com/en-eu/products/emc/esd/sol_antenna_loss

Usually you add an inductor to try and make the final stage think the antenna is matched, when in fact it isn't.

Any mismatched antenna will not radiate 100%, so it's best to avoid them if you have low power or have very little spare path loss.

We have them as auto tune units on HF aerials to compensate for droop, and bird loading ..

They work well until 2-300 hundred starlings decide its a great perch, and it can't compensate.

Mark

We did the same too : ) and test with a short burst, it was very cool hearing the relays clicking away, doing their ATU selection : )

I didn't look closely at what the module was, but guessed it was a GPS module, in which case even the metre of co-ax is significant from the passive antenna. It is nice that electronics nowadays is so tiny, it is possible to put the entire radio (or major chunks of it) right at the antenna, rather than trail coax down to a receiver.

Thank you for all your answers !

So If i understand , I shouldn't go for an inductor, and look at a nice diode,

Can I use a basic TVS or I should buy a A-TVS (there is no electronic part store near my city (basically not a lot in my country)

I'm not sure what you're attempting to protect against.

Do you live or drive near a high powered transmitting station.?

I think the diode might be better unless they have specified the inductor value.

Mark

I Asked my question because the inductance value wasn't specified (F = 1545.42 Mhz)

Actually I plan to make a board to play with gps and rf in general and put this on a bike, so i think esd will be a problem since the antenna will be on the handlebar

By the way do you guys have any suggestions about documents/videos/ICs/things about RF that I can check (like a hand-solderable LNA , i know how to solder tiny SMCs but cant find one big enought)

Hi Nicolas,

The part will be tiny (of the order of 1mm in dimensions) because of the capacitance mentioned earlier, that needs to be minimized, otherwise there will be no usable signal. 1mm is hand-solderable, I don't know of any recommended videos but if you google 'soldering 0402 components' you'll find what you need.

I think you're over-thinking this, and the result will be no usable signal and a damaged antenna cable (if you're planning to cut the cable to insert this device). You can buy it ready-made here for $49: TPD1E0B04EVM TPD1E0B04 1-Channel ESD Protection Diode for USB Type-C and Antenna Protection Evaluation Module | TI.com  or you can try to make it, but it is 1.0x0.6mm in size