Table 4.

Performance comparison of our proposed TE₂₀-mode SIW resonator with other RF multichannel sensors.

Ref.	fo [GHz]	Δf * [MHz]	εa **	εr	S [MHz/εr]	Physical Size	Electrical Size †	Dielectric Constant of Substrate
This work	8	430	5	4	107.5	60 mm × 40 mm	2.37 λg × 1.58 λg	2.2
[22]	3	170	6	5	34	35 mm × 32 mm	1.12 λg × 1.02 λg	10.2
[23]	6.5	400	5	4	100	30 mm × 22 mm	1.13 λg × 0.86 λg	3
[24]	0.87	110	14	13	8.46	86 mm × 62 mm	0.8 λg × 0.57 λg	10.2

* Δf represents the shift in resonance frequency compared with the case of the empty resonator. Conventionally, frequency shifts in RF chemical sensors are compared with reference to DI water. However, because of insufficient data provided by some references, air was considered as the reference media. Therefore, Δf = f_air − f_a, where f_air and f_a represent the resonance frequencies corresponding to air and the analyte, respectively, when present inside one or all channels. ** ε_a values are taken either from the reference mentioned or from [48], which is a standard document for the complex permittivity of dielectric reference liquids. ^† λ_g represents the guided wavelength.