Post History

It is a passive microwave/radio [repeater](https://en.m.wikipedia.org/wiki/Passive_repeater). They were used as an economic way of getting around line of sight obstacles. I came across the information on these researching a way of passively linking an above-ground radio network with another one underground (we went with passive yagi-coax-yagi). My general impression from internet research indicated they have gone out of favor with the advances made in other wireless communication technologies.