In the bistatic radar, it is important to suppress the undesired signals such as the direct propagated signal from transmitter and its multipath components. Conventionally, the suppression method by subtracting the replicas of the undesired signals is often used. However, it requires the precise delay times of the undesired signals. In this paper we propose a new method to detect the target without any information on the undesired signals' delay times in digital terrestrial TV-based bistatic radar, the signal of which is based on orthogonal frequency division multiplexing(OFDM). This kind of the radar is called "passive bistatic radar." We adapt a scheme based on maximum signal to noise ratio(MSN) algorithm, which makes signal to interference plus noise ratio(SINR) maximum for the certain delay component. The maximum sensitivity is steered along the delay which relates to the target position, as if the search beam is steered along the direction in array signal processing. The sensitivity is steered by the weight applied to the received signal in the frequency domain. We obtain the method to estimate the weight to achieve the maximum SINR in the delay estimation which also includes the compensation for the reduction of the weight's length caused by decorrelation among the delay components. The simulation results show our proposed method without any information on the undesired signal's delays provides the sufficient performance compared to the conventional one.