A more simplified photonic microwave frequency measurement configuration based on a loop mirror filter is proposed and experimentally demonstrated. It is implemented by propagating a carrier-suppressed double-sideband modulated optical signal through a loop mirror filter. The ratio between the optical powers of the two output ports provides a direct measurement of the unknown signal frequency. This scheme can solve the main problems that exist in previous work. A proof-of-concept experiment is performed with a measurement range of 6 to 18 GHz and resolution less than 0.35 GHz.