**4. Experimental validation**

An experimental study was conducted to evaluate the 3D HMMW system for concealed MFO detection (see **Figure 10**). A concealed steel ball (10 mm in diameter) embedded in a plastic box (100 × 100 × 40) mm3 that filled of emulsifying wax (see **Figure 10(c)**). An array of 16 openended waveguide antennas with one element for transmitter and others for receivers. The plastic box was placed at *z* = 0 mm, and the sensor array plane was moved from *z* = −600 mm to *z* = −560 mm in 40 equal steps during data collection. During data collection, the VNA excited MMW signals to each transmitter located on the sensor array at frequency of 23 GHz. The scattered signals from the target object were measured by each detector. 2D and 3D images of the target object were reconstructed using the proposed imaging algorithms (as detailed above).

**Figure 10.** (a) HMMW measurement setup; (b) sensor array; (c) target object.

**Figure 9.** Reconstructed 2D image of Model V.

**Figure 7.** (a) 3D reconstructed image of Model III, (b) 3D reconstructed image of Model IV.

134 Emerging Microwave Technologies in Industrial, Agricultural, Medical and Food Processing

**Figure 8.** Simulated S11 value of the designed 4-band patch antenna.

**Author details**

Technology, Hefei, China

\*Address all correspondence to: luluwang2015@hfut.edu.cn

Resonance in Medicine. 2015;**73**(5):2030-2037

Signal Processing Magazine. 2005;**22**(2):52-61

Otorhinolaryngology. 2017;**92**:1

1 School of Instrument Science and Opto-electronics Engineering, Hefei University of

3D Holographic Millimeter-Wave Imaging for Concealed Metallic Forging Objects Detection

http://dx.doi.org/10.5772/intechopen.73655

137

2 Institute of Biomedical Technologies, Auckland University of Technology, Auckland,

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[9] Farsaei AA, Mokhtari-Koushyar F, Seyed-Talebi SM, Kavehvash Z, Shabany M.Improved twodimensional millimeter-wave imaging for concealed weapon detection through partial Fourier sampling. Journal of Infrared, Millimeter, and Terahertz Waves. 2016;**37**(3):267-280 [10] Du K, Wang W, Nian F, Chen W, Hu FJ. Concealed objects detection in active millimeter-

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saliency detection. Infrared Physics & Technology. 2016;**76**:52-64

Lulu Wang1,2\*

New Zealand

**References**

**Figure 11.** (a) 2D reconstructed image of concealed steel ball, (b) 3D reconstructed image of concealed steel ball.

**Figure 11** shows the 2D and 3D reconstructed images of the concealed metallic steel ball. The steel ball is clearly identified in the reconstructed images with correct location, shape and size.
