Resosnt frquency of Radar application

the antenna can be used for radar application in the range

8.4-8.66 GHz

Does any frequency in this range can be used in radar application such as 8.1GHz, 8.6 GHz?

Not sure I understood your question, but short-range tracking radar applications makes use of X-band range, that is 8-12 GHz. Just check your country regulations to make sure that there are not military constraints regarding some specific frequencies within this band.