I actually wanted to broaden the bandwidth of the planar inverted F antenna patch bit; it was too peaky and narrow. I experimented with about four or five variants of the logo until I found one that had the desired effect. So it is true, the peak gain is reduced by this, but the gain in bandwidth meant I had better average gain over the entire 2.4G band.

Unfortunately, I can't definitively explain why it was better beyond some theoretical platitudes -- in the end, it was literally a process of just making educated guesses and measuring stuff until I found something that worked.

I've tried modelling software in the past, but the results don't match well with measurement, and the paid licenses for modelling software are by far more expensive than the cost of copper tape and a good knife, and then running a few prototypes (and the free stuff I could find wasn't even close to meeting the task). Not to mention the time -- the sims take a long time to run, and building accurate models is also quite time consuming.

Sort of a dissatisfying reality, but that's how the sausage got made.