In the hardware documentation for GPSD you may find some other oncore compatible manufacturer.
I dont remeber seeing one specifically but there are quite a few that attempt to mimic another popular manufacturers binary format.
Making a quadrifilar helix GPS antenna is rendered really easy using a nanoVNA2 (using the 2 version is important.
Its basically two loops of stiff wire made so they cross like an egg beater and then twisted approprately. The two loops are rectangularly bent in a square with a gap, and then bent so the gap part is at the top which is where you attach the coax. See the attached files.
See also jc coppens web site,
They are sized so one resonates slightly above the target frequency of 1575.42 MHz and the other slightly below. I have the guts of (an unfinished one) sitting right here. I used approximatey 1 mm copper conduit wire. As long as the two loops resonate at the right frequencies its a no brainer, it basically has to work. The QFH makes a very good antenna because it maintains the right sense of CP (RHCP) properly no matter what angle its used at.
Vaisala's aerosondes contain a nice GPS QFH.. thats the design to emulate, if you can.
I bet it would also be easy to make one using a small cylinder - maybe a pill bottle, and copper tape.
In my experience, GPS antennas are kind of weird. I hear a lot about quadfilar helix antennas for GPS, but I have three survey grade antennas and they are patches. In fact, every GPS antenna I have is a patch. I would actually like to try a quad helix sometime. I have seen articles about how to make one, but I don't trust myself to get it right. Over the years, I have seen all kinds of different GPS antennas described in do it yourself articles, but it always comes back to me that the folks who make the ones relied upon by professionals to give accurate results are always patches.
The GNSS antennas used on GNSS satellites themselves are slightly conical QFH's , for a number of good reasons.
Archimedian and log spiral antennas are also good, especially conical ones which have directional gain. They make good navigation antennas, it seems. better than patch antennas which have some issues. Patch antennas are good for getting accuracy on altitude but they have poor rejection of odd order reflections. which should be cancelled out by the antenna if possible.