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Salt and sugar detection system using a compact microstrip patch antenna

S. N. Njokweni
S. N. Njokweni
 and 
P. Kumar
P. Kumar
   | Sep 15, 2020
International Journal on Smart Sensing and Intelligent Systems's Cover Image
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Article Category: Research-Article
Published Online: Sep 15, 2020
Page range: 1 - 9
Received: May 19, 2020
DOI: https://doi.org/10.21307/ijssis-2020-027
Keywords
© 2020 S. N. Njokweni et al., published by Sciendo
This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

Figure 1:

Antenna geometry: (A) top view, (B) side view, and (C) bottom view.
Antenna geometry: (A) top view, (B) side view, and (C) bottom view.

Figure 2:

Fabricated antenna: (A) top view and (B) bottom view.
Fabricated antenna: (A) top view and (B) bottom view.

Figure 3:

VSWR and reflection coefficient of the antenna.
VSWR and reflection coefficient of the antenna.

Figure 4:

Radiation patterns of the antenna at 2.4 GHz: (A) ϕ = 0 deg. plane and (B) ϕ = 90 deg. plane.
Radiation patterns of the antenna at 2.4 GHz: (A) ϕ = 0 deg. plane and (B) ϕ = 90 deg. plane.

Figure 5:

Measurement setup.
Measurement setup.

Return loss of the antenna in different concentrations of sugar in water.

S. No. Frequency Return loss (concentration: 20%) Return loss (concentration: 50%) Return loss (concentration: 80%)
1 2.38 GHz 23.558 dB 19.123 dB 13.022 dB
2 2.56 GHz 24.251 dB 22.012 dB 13.223 dB
3 2.72 GHz 24.097 dB 21.293 dB 13.144 dB
4 2.86 GHz 22.044 dB 17.272 dB 11.962 dB

Comparison of proposed antenna with existing antennas for salt and sugar detection.

Reference Antenna type Center frequency Dimensions of the antenna Substrate parameters
Cheng et al. (2014a) Rectangular microstrip antenna 2.45 GHz 0.47λ0 × 0.388λ0 εr = 2.2, h = 1.575 mm
Cheng et al. (2014a) Circular microstrip antenna 2.45 GHz 0.465λ0 × 0.465λ0 εr = 2.2, h = 1.575 mm
Cheng et al. (2014a) Square microstrip antenna 2.45 GHz 0.529λ0 × 0.529λ0 εr = 2.2, h = 1.575 mm
Rahman et al. (2018b) Circulated psi-shaped patch 16 GHz 1.28λ0 × 0.96λ0 εr = 2.2, h = 1.57 mm
Islam et al. (2018) Crescent-shaped microstrip antenna 10.6 GHz 1.13λ0 × 0.777λ0 εr = 4.6, h = 1.6 mm
Rahman et al. (2018a) Fork-shaped patch 9.5 GHz 0.76λ0 × 0.57λ0 εr = 2.2, h = 1.57 mm
Proposed method Rectangular microstrip antenna 2.4 GHz 0.41λ0 × 0.41λ0 εr = 4.3, h = 1.5 mm

Optimized dimensions of the compact antenna.

S. No. Dimensional parameter Values
1 L 25.65 mm
2 W 25.65 mm
3 Lg 51.3 mm
4 Wg 51.3 mm
5 Lg1 25.65 mm
6 Wg1 25.65 mm
7 Lg2 24.41 mm
8 Wg2 5.1525 mm
9 g 2.5875 mm
10 h 1.5 mm
11 t 0.035 mm
12 εr 4.3

Dimensions of the antenna with and without DGS.

S. No. Antenna type Area of patch Area of ground plane
1 Antenna without DGS 838.1 mm2 3,352.4 mm2
2 Antenna with DGS 657.9 mm2 2,631.7 mm2

Gain, directivity, and efficiencies of the antenna at 2.4 GHz 2.4 GHz .

Radiation efficiency Total efficiency Max. gain Max. directivity
−1.84 dB −1.97 dB 2.12 dB 3.95 dBi

Effect of slot length on various parameters.

S. No. Slot length Resonant frequency VSWR (at 2.4 GHz) |S11| (at 2.4 GHz)
1 24.95 mm 2.466 GHz 1.514 −13.433 dB
2 25.65 mm 2.402 GHz 1.389 −15.768 dB
3 26.45 mm 2.336 GHz 1.68 −11.913 dB
4 28.95 mm 2.082 GHz 4.624 −3.817 dB

Return loss of the antenna in different concentrations of salt in water.

S. No. Frequency Return loss (concentration: 20%) Return loss (concentration: 50%) Return loss (concentration: 80%)
1 2.38 GHz 23.271 dB 21.017 dB 13.334 dB
2 2.56 GHz 23.757 dB 20.54 dB 13.281 dB
3 2.72 GHz GHz 24.582 dB 19.84 dB 13.046 dB
4 2.86 GHz 23.253 dB 17.095 dB 11.691 dB
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