Mount the nRF24L01+ with extended PCB antenna?

I am working on building a handheld transmitter using an nRF24L01+ and the ATTiny85. I plan to mount it to a single-side PCB with surface mount components. I have preliminarily designed my PBC, but I have not tested any of it, as I am waiting on components.

I was thinking that perhaps I could add antenna length on the PCB, since I am planning on making my own anyway. I have had a range of about 13-20 feet indoors with this radio, and it would be nice to add a little more if possible. I know there are external antenna versions out there for sale, but would rather deal with the shorter range than go that route.

Does anyone have a suggestion of what that might look like? The one on the radio board is zigzagged, though I have seen other versions that are hook-shaped. Does the length or shape matter?

I appreciate any insight. Also, as I said, I have not tested my schematic, so if you see an obvious error, I would appreciate the heads up.

Thanks.

nRF24L01Pluss_Preliminary_Product_Specification_v1_0.pdf (1.06 MB)

PCB antenna design is an advanced topic and requires expensive equipment for testing. Google for more info.