Is it supposed to be one solid model? It's made of several subobjects glued together. The antennas(?), their bases, the upper and lower main sections, the thin block in the middle, the four large bumps and the small bump on the narrow side.
Hmmm, that's not good, I tried joining the three main chunks together and the geometry borked itself...
Solution, BEFORE joining the three big parts, select the middle thin bit, rightclick the Object Tool (white arrow) button to open the object properties panel and set its Z dimension to .800 Then it will boolean join cleanly with the upper and lower chunks.
If you intend to boolean this whole part together, all four antennas and the upper antenna bases need their positions adjusted so they actually intersect the other parts. After joining it all it would still Decompose (the disjointed figure button) into the main section, the upper antenna bases and all the antennas. So just adjust the Z position of those parts a bit.