Narrow Resonant Double-Ridged Rectangular Waveguide Probe for Near-Field Scanning Microwave Microscopy

  • Kim, Byung-Mun (Department of Electrical Electronics, Gyeongbuk Provincial College) ;
  • Son, Hyeok-Woo (Hanwha Corporation) ;
  • Cho, Young-Ki (School of Electronics Engineering, Kyungpook National University)
  • Received : 2017.02.01
  • Accepted : 2017.09.08
  • Published : 2018.01.01


In this paper, we propose a narrow resonant waveguide probe that can improve the measurement sensitivity in near-field scanning microwave microscopy. The probe consists of a metal waveguide incorporating the following two sections: a straight section at the tip of the probe whose cross-section is a double-ridged rectangle, and whose height is much smaller than the waveguide width; and a standard waveguide section. The advantage of the narrow waveguide is the same as that of the quarter-wave transformer section i.e., it achieves impedance-matching between the sample under test (SUT) and the standard waveguide. The design procedure used for the probe is presented in detail and the performance of the designed resonant probe is evaluated theoretically by using an equivalent circuit. The calculated results are compared with those obtained using the finite element method (Ansoft HFSS), and consistency between the results is demonstrated. Furthermore, the performance of the fabricated resonant probe is evaluated experimentally. At X-band frequencies, we have measured the one-dimensional scanning reflection coefficient of the SUT using the probe. The sensitivity of the proposed resonant probe is improved by more than two times as compared to a conventional waveguide cavity type probe.

E1EEFQ_2018_v13n1_406_f0001.png 이미지

Fig. 1. Block diagram of an waveguide probe for near-fieldscanning: (a) the conventional probe (b) theproposed probe

E1EEFQ_2018_v13n1_406_f0002.png 이미지

Fig. 2. Waveguide probe and substrate SUT

E1EEFQ_2018_v13n1_406_f0003.png 이미지

Fig. 3. Equivalent transmission-line model for the proposedprobe with open-ended DRWG: (a) with an idealtransformer, (b) without an ideal transformer, (c) if=∞ in the case of Fig. 3(b)

E1EEFQ_2018_v13n1_406_f0004.png 이미지

Fig. 4. Reflection coefficient

E1EEFQ_2018_v13n1_406_f0005.png 이미지

Fig. 5. Turn ratio n2 of the transformer and the normalizedradiation admittance

E1EEFQ_2018_v13n1_406_f0006.png 이미지

Fig. 6. Normalized input admittance at the interfacebetween the input RWG and the DRWG

E1EEFQ_2018_v13n1_406_f0007.png 이미지

Fig. 7. Calculated reflection coefficients of the proposedprobe

E1EEFQ_2018_v13n1_406_f0008.png 이미지

Fig. 8. Optimum length of the open-ended DRWG for theproposed probe

E1EEFQ_2018_v13n1_406_f0009.png 이미지

Fig. 9. Electric field intensity distribution on the SUTsurface (

E1EEFQ_2018_v13n1_406_f0010.png 이미지

Fig. 10. Peak intensity of electric field

E1EEFQ_2018_v13n1_406_f0011.png 이미지

Fig. 11. Experimental equipment arrangement

E1EEFQ_2018_v13n1_406_f0012.png 이미지

Fig. 12. Layout of a PCB with seven strips with width of0.5 mm

E1EEFQ_2018_v13n1_406_f0013.png 이미지

Fig. 13. Measurement results of the SUT in Fig. 12 atresonant frequencies of 9.642 GHz and 10.330 GHz

Table 1. Dimensions of the proposed probe

E1EEFQ_2018_v13n1_406_t0001.png 이미지


Supported by : National Research Foundation of Korea (NRF)


  1. M. T. Azar, J. L. Katz, and S. R. LeClair, "Evanescent microwaves: a novel super-resolution noncontact nondestructive imaging technique for biological applications," IEEE Trans. Instrum Meas., vol. 48, pp. 1111-1116, Dec. 1999.
  2. E. A. Ash and G. Nicholls, "Super-resolution aperture scanning microwave microscope," Nature, vol. 237, pp. 510-512, 1972.
  3. Wael Saleh, Nasser Qaddoumi, "Potential of nearfield microwave imaging in breast cancer detection utilizing tapered rectangular waveguide probes," Computers & Electrical Engineering, 4th IEEE Gulf Cooperation Council Conference, vol. 35, no. 4, pp. 587-593, July 2009.
  4. A. Dechant, S. K. Dew, S. E. Irvine, and A. Y. Elezzabi, "High-transmission solid-immersion apertured optical probes for near-field scanning optical microscopy," Appl. Phys. Lett. 86, 013102, 2005.
  5. T. Nozokido, T. Ohbayashi, J. Bae, and K. Mizuno, "A Resonant Slit-Type Probe for Millimeter-Wave Scanning Near-Field Microscopy," IEICE Transactions on Electronics, vol. E87-C (12), pp. 2158- 2163, Aug., 2004.
  6. Abu-Teir M., Golosovsky M., Davidov D., Frenkel A. and Goldberger H, "Near-field scanning microwave probe based on a dielectric resonator," Rev. Sci. Instrum. 72, 2073 (2001).
  7. J. Nadakuduti, G. Chen, R. Zoughi,"Semiempirical electromagnetic modeling of crack detection and sizing in cement-based materials using near-field microwave methods," IEEE Trans. on Instrumentation and Measurement, vol. 55, no. 2, Apr., 2006.
  8. N. Qaddoumi, "Microwave detection and characterization of subsurface defect properties in composites using open ended rectangular waveguide," Ph.D. dissertation, Dept. Elect. Comput. Eng., Colorado State Univ., Fort Collins, 1998.
  9. B. M. Kim, H. W. Son, J. P. Hong and Y. K. Cho, "A novel epsilon near zero tunneling circuit using doubleridge rectangular waveguide," J. Electromagn. Eng. Sci. vol. 14, no. 1, pp. 36-42, 2014.
  10. B. M. Kim, H. W. Son, J. P. Hong and Y. K. Cho, "Transmission-line analysis of an epsilon near zero tunneling circuit using a double ridge rectangular waveguide," Journal of the Korean Physical Society, vol. 65, no. 5, pp. 625-630, Sep. 2014.
  11. S. N. Hsich, T. H. Chu, and M. T. Chen., "Scanning Near-Field Microwave Microscope Using a Rectangular Waveguide Probe with Different Resonant Modes of Cavity," Proceedings of the Asia-Pacific Microwave Conference, pp. 1402-1405, 2011.
  12. H. W. Son, B. M. Kim, J. P. Hong and Y. K. Cho, "Theoretical and Experimental Investigation on the Probe Design of a Ridge-loaded Slot Type for Near- Field Scanning Microwave Microscope," J Electr Eng Technol. vol. 10 no. 5, pp. 2120-2125, 2015.