## 4 Conclusions  
In this study, we presented a reduced-size patch antenna that can be used for MRI and RF heating. The size of the patch antennas was reduced by 61% width and 28% length using a meandering pattern in both the horizontal and vertical directions on the ground and patch plane. The designed patch antenna could produce a resonance mode at a frequency of 300 MHz corresponding to 7T MRI system. At this frequency the \(\mid\)B\({}_{1}\mid\)-field is uniform for which it can be used for MR image. At a same time, the antenna had a resonance frequency at 1.06 GHz, at which the \(\mid\)E\(\mid\) field is used for RF heating procedures. We verified each resonant mode and determined the one corresponding to the dominant \(\mid\)E\(\mid\)-field such that it can be used for the application of RF heating. We also proposed a two-patch antenna configuration capable of producing a circularly polarized and uniform \(\mid\)B\({}_{1}\mid\)-field. However, this configuration can only be applied for small animal applications because the antennas are arranged along the \(z\)-axis and the position of the animal can be more easily controlled. The double patch antenna configuration also produced a strong and focused \(\mid\)E\(\mid\)-field, such that it could induce a temperature increase in a target cancer mimicking tissue. By reducing the size of the antenna, we have proposed a challenging antenna design; however, this can be achieved by using layers of copper tape attached to the dielectric material and then soldering each other. We can also create complex structures by using a 3D printer. A double tunned matching circuit can be developed for this application; however, it is outside of the scope of this work. For the case that the Hyperthermia procedure is applied in a separate time than MR imaging, an extra switch can be used to select corresponding the matching circuits. The proposed design of the patch antenna configuration can be used for combination of MRI acquisition for temperature measurement and hyperthermia with RF heating for treatments or preclinical studies with rats or mice. In the future, we will research on optimization of size adjustment for operating frequency, input power and exposure time for hyperthermia.  
Figure 10: Temperature comparison as a function of time between healthy tissue (without RF heating focus) and cancer tissue (with RF heating focus) (**a**). The histogram of the temperature change on time in terms of normalized volume, for the case of (**b**) the cancer tissue, (**c**) the healthy tissue.  
**Author Contributions:** Conceptualization, D.H.; methodology, D.K.; validation, D.K. and D.H.; formal analysis, D.K.; writing--original draft preparation, K.-N.K.; writing--review and editing, K.-N.K.; funding acquisition, K.-N.K. All authors have read and agreed to the published version of the manuscript.  
**Funding:** This work was supported by the Institute for Information and Communications Technology Promotion (IITP) grant funded by the Korean government (MSIP) (No. 2021-0-00490, Development of precision analysis and imaging technology for biological radio waves) and supported by Gachon University under the Gachon University research fund of 2018 (GCU-2018-0672).  
**Institutional Review Board Statement:** Not applicable.  
**Informed Consent Statement:** Not applicable.  
**Data Availability Statement:** Not applicable.  
**Conflicts of Interest:** The authors declare no conflict of interest.