Perhaps you should try some spelling variations:
"groups generating radar" » "groups generated radar", "groups generators radar", "groups operating radar", "groups penetrating radar", "groups penetrating radars", "groups generating random"
"groups generation radar" » "groups generated radar", "groups generalized radar", "groups general radar", "groups generation raman", "groups generation radio", "groups generation random"

Try widening your search to All Fields.

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

• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"groups generating radar\") OR (\"groups generation radar\"))".
• Removing quotes may allow a broader search: (( groups generating radar ) OR ( groups generation radar )).
• Adding a wildcard symbol may retrieve word variants: (("groups generating radar") OR ("groups generation radar"))*.