I’ve been using various antennae and I find the square ceramic one with the short wire (10 cm) performs best by far.
For a long while I played around with the stubby screw-in type, the magnetic puck that sits on the roof with a 3m cable and even just lengths of plain wire. All worked but I came to accept long times to get a fix as normal (10 to 30 minutes). I was jealous of railroader’s claims of getting a fix within a minute.
Now it’s normal for mine to get the time within a minute & a fix within 2 or 3 minutes. The unit sits on the dash secured with double sided adhesive tape (never use blutack - it leaves ugly residues you can’t remove). It even sometimes gets results indoors.
I did a 200km trip today. The device worked well except for a few minutes when it was wet and plenty of trees.
Stick with it - it makes a great driving aid.