**2.2 Advantages of gallery modes for temperature detection**

Among the main advantages of gallery modes, we will note here the most important for our study. First of all, the dimensions of the resonator excited on a gallery mode are much larger than in the case of conventional TE or TM modes. This oversizing makes it possible to consider the use of this resonator at millimeter frequencies by facilitating temperature detection. On the other hand, thanks to the high-energy confinement in the dielectric, the vacuum quality factors are practically limited only to the loss tangent of the material used [3]. The latter will thus be very sensitive to the presence of a variation in the dielectric properties of the sensitive material, which will improve its detection thanks to an offset in the resonance frequency of a gallery mode.

In addition, it is important to note that the gallery modes have the particularity of not having any energy at the center of the resonator. As mentioned earlier, the larger the azimuth number, the larger the area. The central part can therefore be used to fix the resonator; we can add a shim to the circuit in order to maintain it or adjust its position in relation to the coupling circuit (lines) without disturbing its operation. Finally, these modes are no longer stationary but progressive when the resonator is excited by a progressive wave source, whose propagation constant is close to that of the gallery mode. The mode then propagates in the azimuthal direction. This type of excitation for gallery modes results in a directional coupling with the line. Therefore, this coupling will make it possible to consider the design of a directional filter with a narrow bandwidth, which in turn will allow temperature measurement thanks to the shift in its resonance frequency.
