Attached is a photo of a PCB antenna that I thought you guys might find it interesting. It's from Version 2 of a flume water meter monitor. Looks like it's maybe (?) some kind of dipole antenna, though up close the construction is fairly intricate. I have close-up photos if anyone is interested in having a closer look or would like to comment.
By the way, the Version 1 Flume also used HopeRF RF69 and even an atmega328p MCU, so you all would have been completely at home with it. It even communicated with an ESP8266 gateway node, much as what some of us here were doing. For Version 2 they kept the RF69 but switched to an ATSAMD20. I wonder why? Aside from that, the main differences between version 1 and 2 were the use of this new, fancier antenna, and a simplification of the moistureproof enclosure (no screws holding the cover on Version 2, as compared to 12 self-tappers holding on the lid of Version 1).
I didn't own a version 1, but I very much like my Flume version 2. It seems like a simple, yet very nicely engineered IoT device that does pretty much exactly what I want it to: log water consumption down to the nearest 0.01 gallons for every minute of every day, and keep all that data forever, for review whenever I like. Nifty!