Wireless HDMI from camera to mixer?
Yes, they exist. They are called HDMI wireless extenders. Sometimes they are called transmitters/receivers. No, the good ones are not cheap. Further, I don't know of any where the receiver does not need external power.

Here's two examples, a better one and a not so better one:


IOGear Matrix pro (Here's a different offering)
Gefan Long Range Extender


I have no experience with either product and practically none with wireless HDMI as a whole. Personally, I would always use a wire for something like video. If you're only going 30 feet, it's really not a big deal to have a wire, and HDMI can go 30 feet just fine. If you need more distance, there's extenders of various wired variety that I would prefer over wireless options.



From your comment below, it sounds like you are wanting to move throughout the event, therefore making a wireless solution optimal, allowing you to move about on your whim.

If you do not have to stream the feed to the internet, I suggest that instead of running your video wirelessly, run the audio only. Get yourself a wireless audio transmitter and receiver, then carry the receiver around with you and the camera, plugging in the audio receiver to your camera. There are literally thousands of options and should be easy to find with google. Alternatively, get a standalone audio recorder and then mix the audio and video together in post.

The downside of these methods is that you must record to the camera's internal media and it may increase your post production time. The upside is that you're mobile while recording.