I worked on a solution to cast unsupported PC to unsupported Miracast device for over a year and placed the solution in an official WIKI page in July of 2021.
Below is a different solution that uses an unencrypted way to connect to any screen/s that supports RF (radio frequency) signal that is within range. It is a type of a wireless display splitter that is only limited by the range of the signal and not the number of the devices.
HDM68 is a device that converts HDMI to RF. I have the HDM69 which converts HDMI or RCA connection signal to RF signal.
The requirements are:
HDM68 or 69 device or a similar device that works on the same principle.
One HDMI cable.
Two indoor TV antennas. (Check the TV antenna connector because not all are the same. An adapter connector can be used as I did for one of the two Antennas.)
All TVs still have RF connection. But make sure that the port is on the TV before making any purchases.
The Setup:
Connect one Antenna to the signal converter and one Antenna to the TV.
Connect the HDMI cable from the PC to the HDM68(9).
Extend or duplicate PC screen depending on the requirement.
Switch on the converter device (select HDMI port if available) and then go to the setting in the TV menu. Use auto Search to search for channels. Stop it after it finds your display.
Audio and Video will now work on the TV.
The advantages of this solution are:
Infinite number of TVs can be connected that are with in range. Works through walls (up to a certain limit). Works with any HDMI device. The RF signal can be picked up by any RF receiver including radio that works on the same bands. So Audio can be picked up from a HI-FI system if it meets the requirements.
The disadvantages are:
The resolution drops and is not too good for text but it is good enough for video.
No encryption, so anyone with an Antenna can pick up the signal that is with in range.
You are correct in your summary and usage scenario for broadcasting HD content over RF, especially in public spaces like sports bars. Here’s what you outlined:
HDMI Extender over WiFi: Good for point-to-point streaming but not for broadcasting to multiple TVs.
HDMI to Digital RF (Modulator, e.g., HDMI to ATSC RF Modulator): This converts an HDMI signal to a digital TV signal (ATSC), which can be broadcast over standard coaxial cabling and received by multiple TVs with digital tuners. These modulators start at around $110.
HDM68 Device: An affordable device ($20-40) referenced as part of another solution, possibly for analog or limited digital applications.
Requires Indoor Digital Antenna: Needed to distribute the RF signal to TVs.
No Encryption: Makes it ideal for public areas since there are no limitations on receiver compatibility.
Key search terms: “HDMI to ATSC RF modulator”
If you need more specifics on setup, brands, or technical details—or want to compare options in more detail—let me know!