Gps antenna in kraken

I use 5 similar gps antenna in uca with 10cm radius ,and put signal in fc=15757mhz with aknown direction but i dont get correct doa ,but in using another antenna i get a correct direction,can you help me?

Do the GPS antennas have built in LNAs?

Yes,and i use the bias tee from the kraken

GPS antennas will have built in LNAs and filters, and they might not all have the exact same phase characteristics. So it’s possible that this is skewing your results. Especially at 1.5 GHz, even small phase changes caused by the LNA or filtering could result in big changes.

So external calibration would be a feasible option the?, just like keratose sdr

External calibration could be one idea, but you’d have to implement that yourself.