Terminated & Unterminated RF Broadband (DC-50GHz) EM Swi

Hi everyone,
Need your opinion:

1) What is the different between terminated em switch and unterminated em switch?

2) What is the advantage & disadvantage both terminated and unterminated em switch?

3) Is there any different in term of RF performance (Isolation, Return Loss & Insertion Loss) between terminated and unterminated em switch?

Hope to hear from you.

Alex.

terminated switch example:
http://www.digchip.com/datasheets/pa.../HMMC-2007.php
unterminated switch example:
http://www.digchip.com/datasheets/pa.../HMMC-2006.php

At 50Ghz you can't use unterminated switch, even the way you're connecting the N connectors counts.