Is this a type of navigation aid?
If you go to www.skyvector.com and zoom in to MRB
(easy to enter a flight from KOKV to KMRB to find it quick)

Select the World VFR view, and you will see no navaids at that location. 
Select the Enroute L-29 view, and you will see no navaids at that location.

So no, it is not a type of currently used navigation aid.

If you peruse the Instrument approaches for KMRB at Airnav.com  https://www.airnav.com/airport/KMRB

you will also not see that structure mentioned.

Airport phone numbers are listed, you could call up and ask what it is.