Huh, first time I've ever seen that. Most of the designs I've seen in ghetto ham sites shows a wire that has like a splice to a spike driven a few feet into the ground.
Not that it matters regardless. My little tecsun is broken and I can't afford a new radio, nor is there much to listen to in the US anymore, especially where I'm at
Some types of antennas do need an "earth" ground to work, but this device goes between the antenna and your receiver. It only comes into play when the potential between the incoming line (your radio) and ground (the case) exceeds a certain value. Otherwise, it's just a connector.
Not too bad.. 0.2 dB loss, but only handles 200W.. That could be a problem for amp use..
There are others out there, that was simply the first I found.