Follow Me mode while Mountain Biking - Where to place antenn

Hi Folks. I’m going to be using my Iris+ in Follow Me mode with the Tower app, and I was curious if any of you have experience with this.
My first question is, where do you put the phone and antenna? Can the phone screen be in sleep mode or does it need to stay responsive? Can I put this in my pocket or does the antenna need to maintain a line of sight to the drone?

I’ve had some luck placing the phone in a chest pocket. By far the best is when the antenna has a clear line of site. The phone cannot sleep. There is a setting, which I think is on by default, in Tower (and the older Droidplaner 2) which keeps the phone from sleeping while connected to the Iris+