We present a nondestructive method for determination of the permittivity and loss tangent of low-loss dielectrics using printed circuit board (PCB) circular disks. Because it utilizes multiple resonances, this method is in high precision and broadband (500 MHz-12 GHz), covering the UHF, GSM 850/1800, 802.11b/g, WiMax, WLAN, and UWB bands. The method is simple and accurate based on closed-form analytic expressions of cylindrical symmetry, taking into account disk rim fringing fields and radiation loss. Numerical results are conducted for popular PCB material, FR4, and the self-consistent Kramers-Kronig (KK) relation is verified.