QUESTION

Question

We have used in our design for a car alarm system the M20047-1 active antenna module. Target application is GNSS signal reception.

We have followed the pcb design guidelines and we see output signal. Nevertheless we have a two ANT design; one implemented with M20047-1 and another with coax receptor for an external ANT.

We observe following behaviour.

- When a external ANT is connected and then disconnected we have signal from the active antenna but with intermittencies.

- From cold boot, we never observed signal from the active ANT when we boot without external ANT.

We used your exact logical design with the two external components (L=8,2μH and R=0) but in order to get signal the L was shortcircuited as well.
Any ideas on how to improve performance?

Many thanks

Spiros

Qualtek

Answer 1

Hi, I checked the datasheet, and it gives the value for L2 as 1.8nH.  As is shown in the reference schematic, you also need an inductor L1 47nH, and a DC blocking capacitor of 22pF.
Regards,

Michael