SIM908 GPS antenna reception not working

I am using SIM908 GPS_ANT pad to connection to an SMB connector from where it is connected to external(passive) GPS antenna. But SIM908 is unable to track even a single satellite. I have used other GPS modules and signal loss due to impedance mismatch can cause degradation of signal resulting in less satellites being tracked. But in this case not a single satellite is being tracked which is strange. I did not use the pi impedance matching circuit given in the SIMCOM manual but I I have tried to make trace to be 50 Ohms matched (8 mil width + 8 mil gap to ground on both sides).

Now I have also used GPS antenna connected directly on the SIM908 module but same result.

Can anybody shed a light on this problem? Am I missing some settings?

Thanks.


SIM908 GPS output after AT+CGPSPWR=1 and AT+CGPSRST=0

$GPGGA,000115.001,,,,,0,0,,,M,,M,,*4C
$GPRMC,000115.001,V,,,,,,,101010,,,N*48
$GPGLL,,,,,000116.001,V,N*7D
$GPVTG,,T,,M,,N,,K,N*2C

Hi, I think the problem is the passive GPS antenna.
SIM908 must be used with active GPS antenna (which includes a LNA - low noise amplifier).
I use a active patch antenna with build-in 28dB LNA.