In recent years, there is lot of interest to explore the use of microwaves for imaging, nondestructive testing, characterization and remote sensing of materials, media and objects. It has got application in a number of areas spanning over many branches of science and engineering. The main advantage offered by microwaves is that they can provide information about the inner structure of the media or objects by carrying out measurements at the surface. The determination of complex permittivity of the material or the object under test is the basic problem in the microwave characterization, imaging and sensing. Some of the applications, where the dielectric properties data of the material or the object under test in the RF/microwave frequency range are required, are as follows:


  1. The microwave imaging is relatively a new area of research, where the idea is to make use of low power microwaves to determine the electrical and physical properties of the object or medium under test. It is an efficient diagnostic procedure for non-invasively visualizing dielectric properties of non-metallic bodies. It may be noted here that these properties of the object can not be measured using any in-situ procedure, as any direct or in-situ methods are usually destructive in nature. The measurement of dielectric properties of a variety of materials over a wide frequency band is the first and quite crucial step in order to pursue this new research field of microwave imaging and sensing.

  2. For planar antenna and filter applications, the accurate determination of dielectric properties of the substrate is quite important for getting optimized performance as well as for performing accurate simulations. The knowledge of dielectric properties of the host material is equally important for RFID tags as well as for meta-materials.

  3. In civil engineering applications, the microwave techniques are being explored to be used in a number of areas starting from remote sensing, surveying, geophysical prospecting and archeological applications to the nondestructive evaluation and testing of concrete structures and buildings. The basic idea behind microwave nondestructive testing and remote sensing is that various objects in the underground and the concrete structure can be differentiated due to their difference in dielectric properties.

  4. For biological applications, there is a lot of interest to use microwaves nowadays for the imaging of soft tissues as they have substantial difference in their dielectric properties. It has recently been established that dielectric properties of cancerous or malign tissues are quite different from that of the healthy tissues. This principle has been explored to detect the breast tumor at an early stage. As the photon energy of microwave is sufficiently low, hence it is considered to be relatively safe compared to X-rays. However, to fully explore this research field, the dielectric properties of a number of biological tissues (both healthy and malign) should first be accurately determined in order to find out the contrast between dielectric properties of two types of tissues.

  5. The advanced composites are nowadays quite often being used in lieu of conventional metals in the aerospace and luxury automobile industries for increasing the strength to weight ratios, and thereby reducing the weight of the airplanes and high end cars. However, one of the bottlenecks till now in the wider applicability of these advanced composites is their higher costs as compared to their metal counterparts. There is some research going on in recent years to cure these composites using microwaves, which actually helps in saving the energy by a substantial amount. The knowledge of dielectric properties of all the associated materials is crucial in order to find their suitability for microwave curing applications.

  6. There is lot of interest nowadays to use nano-particles in order to modify the material properties of the base polymer matrix. As the amount of nano powder added to the matrix is usually small, hence it is quite difficult to observe the effect of these powders using any direct method. The measurement of dielectric properties of the nano-modified samples over a wide frequency band provides the possibility of studying the effect of nano particles on the material properties of the base material.

It is obvious from above discussion that the establishment of an experimental test facility for measuring the dielectric properties of a range of materials over a wide frequency band is quite beneficial for researchers working in different field of science and engineering. This kind of facility is also helpful in doing some inter-disciplinary research, where researchers from various fields and background can come together in order to achieve a result oriented goal. The procurement and installation of dielectric probe kit in the Department of Electrical Engineering is the first step in this direction.