Found an old Pharos PX003 active GPS ceramic patch antenna, from the iPaq days, in the junkbox, so thought to try it out on Outernet. Opened the case, removed the 1575MHz filter, bridged the trace, shortened the cable length by half, installed a SMA connector, put it all back together, connected directly to RTL-SDR, and it seems to work pretty well sitting on top of the plastic box, in the window.
GPS antenna is almost identical to the one pictured here:
http://www.rtl-sdr.com/rtl-sdr-tutorial-decoding-inmarsat-std-c-egc-messages/ (How to Modify a GPS Antenna for Inmarsat Reception)
This type of antenna will set you back at least $9. http://a.co/5P41aMJ
You will want to have access to a SMD rework station or fine hot air gun to remove the filter easily, leaving traces intact. You will want to shorten the lead considerably as RG-174 is terrible at 1.5GHz.