I. Introduction
Computer tomography (CT), X-ray imaging, Positron-emission tomography (PET), ultrasound, magnetic- resonance imaging (MRI) are popular technologies in medical diagnosis for identifying cancer, tumor, stroke, and some other malignant human-headed components. The significant drawbacks for CT and X-ray imaging are, however, hazardous radiation with a high false-negative rate, reduced sensitivity, increased risk of cancer due to shorter dose and ionizing radioactivity [1], [2]. Several research works have concentrated in recent years on generating a microwave image of a human body to identify and diagnose various ailments like cancer, stroke, tumor, inner-bleeding etc. [3] –[6]. Microwave Imaging (MWI) technology is one type of detection technology that uses electromagnetic waves in microwave frequency ranges to estimate concealed substances in a medium [7], [8]. In comparison with other technologies, the benefit of microwave-based technology is that it is low-profile, lightweight, minimal-cost, and non-ionizing [7]. The main strategy of medical microwave imaging (MI) and detection techniques is to discrepancies in dielectric properties between regular-healthy tissue (without malignant tissues) and unwanted-unhealthy tissue (malignant tissues) in the human head [9]. Malignant tissues such as brain tumor is a mass or formation of abnormal human brain tissues or cells. However, it is possible to view, process and interpret reflected signals from the head in the microwave imaging system and then gather information to create images on a specific portion of the head that determines the placement of the tumor and cancer tissues [10]. Tomography [11] and microwave radar technique [12] are two techniques that have been introduced for active MWI approaches to detect brain disorders, such as cancers, tumors, and other anomalies. The purpose of the technique of tomography is to use the narrowband microwave pulses sent over the head to get the properties of the dielectric profile of the brain. For efficient data acquisition, such systems allow a wideband of frequencies from 1 to 4 GHz with compact antennas [13], [14]. Most analysts want the dipole antenna to collapse in head imaging frameworks because it can offer wide-band with matching great impedance [15]. Patch antenna has recently returned to a hot theme in the field of wearable head imaging research [16]. By being fast, convenient and utilizing non-ionizing radiation, a microwave system for head imaging may be an effective tool for recovering the critical patient within a short period of time.