Wireless communication modules transmitting through body

Question

I wanted to be able to transmit data from a wireless module to an Arduino. It is possible that a human body could come between the wireless module and the Arduino or someone might cover up the module with their hands. So I was looking for some kind of wireless module around 100 MHz because the human body transmits these signals without interference or absorption. I have found many 433 MHz radio wave modules online but nothing around 100 MHz range.

I was wondering if there is any off the shelf component or is there a simple strategy for creating a wireless module around this frequency range on my own?

Answer 1

The reason you can't find many modules around 100 MHz is that it's not an open frequency and you generally need a permit to transmit at those frequencies. Another reason is that you will face some serious interference from FM radio broadcasts that are all in this frequency region.

I'm not sure what size you imagine your module being but at 100 MHz the antennas start to become unpractical, lower frequencies means longer wavelengths which require longer antennas.

I would recommend starting with a 433 MHz radio and see if you encounter problems before you go to the lower frequencies. Note also that two 433 MHz modules can have vastly different performance depending on their antenna design, amplification circuit, pcb-design, etc. so don't dismiss 433 MHz just because you have a poor experience with one module. A popular choice is the RFM65/69 (69 is 915 MHz) modules. Also have a look at LoRa, they offer excellent range but I have no idea about how they are affected by being blocked by a body.