In this study, a novel microstrip antenna sensor with defected ground structure is investigated to detect the presence of other substances in liquid food samples. The proposed antenna sensor is rake-shaped which has been designed using time domain solver in three-dimensional simulation software Computer Simulation Technology Microwave Studio. The proposed antenna sensor has been fabricated using an FR4 material, having overall dimensions of 30 × 27 mm2 with dielectric constant 4.4, substrate thickness 1.57 mm, and loss tangent 0.0025. Furthermore, the Q-factor of the proposed antenna sensor is 485 showing a maximum sensitivity of 700 MHz and having accuracy 98%. In the present work, water and juice are considered as liquid samples in which the presence of foreign substances is detected in terms of reflection coefficient and shift in resonant frequency with the help of the suggested microstrip antenna sensor. Through experimentation, it has been observed that with the increase in the percentage of adulterant in the considered samples, the dielectric property of solution changes which results in shift of reflection coefficient and resonant frequency, thus making an allowance for the proposed antenna sensor a valid tool to detect adulteration in liquid samples.