Abstract: A novel passive radar imaging method is presented using distributed apertures that relies on illuminators of opportunity. The measurement is modeled using the wave equation. A new passive measurement model is proposed that expresses the measurement at a receiver in terms of the measurement at a different receiver and therefore requires no information about the illumination sources. Since only a limited number of measurements are available due to sparsely and randomly distributed apertures, the imaging issue is formulated as a binary hypothesis test with unknown target location. The spatial-resolved test-statistic is determined by maximizing the SNR of the test-statistic using the proposed passive measurement model. The resulting image is formed with the test-statistics evaluated at each hypothetical target location, which can provide the information about the target location. The resolution analysis of the imaging method is presented and numerical simulations are conducted to verify its performance and validate the theoretical findings.