Here are pointers to web pages that have test comments on several low quality antenna parts sold to be used in TV antenna networks. The documents are written in Finnish, but the documents have lots of pictures that tell most of the facts easily to all people who can see the difference between good and bad antenna parts:
Cable TV outlet set sold by LIDL:
http://www.mattikaki.fi/laitetestit/ant ... steemi.htm
Product package:
Look the document for details of construction inside.
Antenna splitters sold by ELEXI:
http://www.sci.fi/~oh2bio/antennit/elexi.htm
Product packages:
Bad construction inside:
Example of good antenna splitter construction:
The document contains also information on Biltema antenna amplifier.