I've bought a few 50MHz-6GHz directional couplers ([SEDC-10-63+][1],) each for 75$. Here is a picture of this expensive coupler:

[![directional coupler][2]][2]


Unfortunately one of these couplers was not working from the beginning so I decided to take the cover off and get a glimpse of the insides. 

The problem is I cannot understand what this big black component is (probably a ferrite,) what it does, and how it contributes to the coupling or directivity.

##Coupler Inside

[![enter image description here][3]][3]
[![enter image description here][4]][4]

I also wondering if the cover is anything more than a simple cover. The top cover feels like a plastic but sounds like a ceramic object.

##Cover

[![enter image description here][5]][5]
[![enter image description here][6]][6]

##Update 1
What does this 1150 component do? connect output to the coupled port? Doesn't this decrease the directivity?
[![enter image description here][7]][7]



  [1]: https://www.minicircuits.com/pdfs/SEDC-10-63+.pdf
  [2]: https://i.sstatic.net/PMT5n.png
  [3]: https://i.sstatic.net/FniqO.jpg
  [4]: https://i.sstatic.net/0taE0.jpg
  [5]: https://i.sstatic.net/HNwC6.jpg
  [6]: https://i.sstatic.net/1ZFJ6.jpg
  [7]: https://i.sstatic.net/miNnF.jpg