Well, if this is a learning exercise, then consider my previous advice about "...building a standalone dipole [or a simulation of same] using two of the little helical monopoles..."
The point is to separate the variables. Learn what the helical monopole 'looks like' (on the Smith chart or equivalent), without being presented with a mixed-up combination view that you'll have a difficult time unpicking.
Just for laughs, build a dipole with two of your PCB counterpoise. That exercise will hopefully help to make clear that the counterpoise cannot be a complete afterthought.
If the counterpoise isn't the ideal ground plane (to mirror the monopole), then it's the other half of a badly mangled dipole.
Regarding tuning the helical monopole, what can you do? Some adjustments to the coil parameters would be equivalent to changing frequency, thus aren't very useful except as the final tuning step.
Axial mode helical antennas, where the CP RF is fired out the end, can be tuned by adding capacitance to the feedpoint by bending the first part of the coil closer to the reflector, or welding a plate onto the start of the coil.
Once you get into that sort of approach, then there are a zillion options. A sim would need to include bulk LC components, or be some fairly advanced software to model such details.
![URL]](https://res.cloudinary.com/engtips/image/fetch/w_800,c_lfill,q_auto,f_auto,g_faces:center/[URL unfurl="true"]http://hi-tecdesigns.com/images/pictures/Footwell%20Animation%20Tiny.gif[/URL])
