Section 73.311 - Field strength contours(a) Applications for FM broadcast authorizations must show the field strength contours required by FCC Form 301 or FCC Form 340, as appropriate.(b) The field strength contours provided for in this section shall be considered for the following purposes only: (1) In the estimation of coverage resulting from the selection of a particular transmitter site by an applicant for an FM broadcast station.(2) In connection with problems of coverage arising out of application of § 73.3555 .(3) In determining compliance with § 73.315(a) concerning the minimum field strength to be provided over the principal community to be served.(4) In determining compliance with § 73.215 concerning contour protection.28 FR 13623, Dec. 14, 1963, as amended at 31 FR 10126, July 27, 1966; 32 FR 11471, Aug. 9, 1967; 52 FR 10570, Apr. 2, 1987; 54 FR 9802, Mar. 8, 1989