Perhaps you should try some spelling variations:
"minimum connectivity" » "minimal connectivity", "maximum connectivity", "minimise connectivity"
"medium connectivity" » "media connectivity", "maximum connectivity", "optimum connectivity"
"medium directivity" » "medium radioactivity", "beam directivity", "edge directivity"

Try widening your search to All Fields.

You may be able to get more results by adjusting your search query.

• If you are trying to use Boolean operators, they must be ALL CAPS: (("medium directivity") OR ((("medium connectivity") OR ("minimum connectivity")))).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"medium directivity\") or (((\"medium connectivity\") OR (\"minimum connectivity\"))))".
• Removing quotes may allow a broader search: (( medium directivity ) or ((( medium connectivity ) OR ( minimum connectivity )))).
• Adding a wildcard symbol may retrieve word variants: (("medium directivity") or ((("medium connectivity") OR ("minimum connectivity"))))*.