Comments on "Evanescent microwaves: a novel super-resolution noncontact nondestructive imaging technique for biological applications" [and reply]

Evanescent microwave principles of operation 1 are based on the papers described by Kumar and Smith [1] and Kumar [2]. They described that when a dielectric/semiconductor/biological material is placed in the vicinity of the evanescent waveguide (which is connected to a cavity resonator), the reflection coefficient of the resonator changes. Both the resonance frequency and the quality factor of the cavity resonator are affected by the presence of the material. The amount of change in the resonance depends primarily on the microwave properties of the sample as well as on the distance between the wall (resonator iris to the evanes-cent waveguide) and the sample, and the effective area of sample in the waveguide. It was also shown that microwave properties of a material are a function of permittivity and permeability. The authors of the above paper have used the same principle, where a microstrip type resonator and an evanescent probe have been used instead of a waveguide resonator and an evanescent waveguide. Therefore , they should have referenced [1] and [2] in the paper. I appreciate the authors using evanescent microwaves to map nonuni-formities in a variety of materials including metals, semiconductors, insulators, and biological and botanical samples. The measurement of the complex permit-tivity of sheet materials using evanescent waveguide technique, " IEEE Trans. An extensive list of published work on the subject of evanescent microwave imagin of materials is presented in the above paper 1. Unfortunately , I was not aware of Kumar and Smith [1] and Kumar [2]. Both [1] and [2] will be properly referenced in future publications on this subject. REFERENCES [1] A. Kumar and D. G. Smith, " The measurement of the complex permit-tivity of sheet materials using evanescent waveguide technique, " IEEE Trans. Chen and Chua [1] have suggested that deviations in the value of resistance in QHR devices with resistive contacts [2], [3] may be attributable to the offset (or bias) current of the nano-voltmeter used to measure the QHR devices. We present two reasons why their explanation is unreasonable. In Fig. 1(a), we illustrate a QHR device as described by Chen and Chua (CC). Precision measurements are usually made in a bridge configuration but for the purpose of this discussion a rather simpler picture will suffice. The device is at field, the 2-dimensional electron gas is quantized, and a source supplies current I SD ad to the device. The Hall voltage (V12) …