Hi
I'm putting together a GNSS receiver based around the ZHONGKEWEI AT6558R-5N32 receiver (AT6558R-5N32 ZHONGKEWEI | Embedded Processors & Controllers - LCSC Electronics)

Basic circuit is OK - I'm reading data from the UART port and when I first powered up the circuit it latched onto the satellites.  

Today I can't get a satellite fix - although the chip is getting a the correct time, so it is getting some data from a satellite

I'm pretty certain the problem is with the antenna circuit - using a Rainsun microwave Tech GPS1003 SMT passive receiver (GPS1003 Rainsun microwave Tech | RF and Wireless - LCSC Electronics)

The reference circuit for the the AT6558R will support an active antenna, so this is where I started, using the ANT_BIAS output from the AT6558R


The Rainsun application guides recommend an antenna matching circuit (which I've not included yet).
This is what V2 of the antenna circuit currently looks like (removing the bias for the active antenna and adding the matching circuit)
I've also removed the Low Noise Amplifier, although this may be a mistake.



Note: I've not gone into impedance matchin on the PCB layout.  This is way beyond my skill level!
This is how the layout of the PCBA (for the revised design with matching circuit add and active bias removed)


Any guidance on how to improve the circuit very much appreciated! 

Thanks

Chris