0.4CaTiO 3 substrates. The 3-dB fractional bandwidth of the crosscoupled filter’s frequency response were 5.1% for Al 2 O 3 ceramic substrate and 4.5% for 0.6Sm(Co 1/2 Ti 1/2 )O 3 -0.4CaTiO 3 ceramic substrate. The bandwidth of each filter agrees quite well with the desirable values. It was found that the skirt properties of the cross- coupled filter were sharper. The dimensions of the compact hairpin filters with different high-permittivity ceramic substrates are provided in Table 1. Figure 5 shows photographs of the fabricated filters. The size of the compact hairpin filter using 0.6Sm(Co 1/2 Ti 1/2 )O 3 -
Abstract A novel type of integrated dielectric antenna is presented, which is suitable for low-loss integrated transceiver front-ends in the upper microwave or millimeter wave frequency ranges. The proposed antenna comprises a dielectric highpermittivitysubstrate acting as grounded slab waveguide and a simple planar lens on top for beam focusing. The guided wave is gradually transformed to free space by a curved ground plane for end-fire radiation from the substrate edge. Apart from high radiation efficiency due to very low conductor losses, the use of a standard substrate material also simplifies manufacturing and allows accommodating MMICs or bias circuitry at minimum cost. Simulation and measurement results are presented for a scaled prototype in X-band. Simulation studies were also conducted at millimeter-wave frequencies, where the low-loss advantage is even more evident. Having dimensions of 10 mm × 18 mm, an example design provides a gain of 15 dBi at 60 GHz and a radiation efficiency of more than 80 % if a Duroid ® 6010LM
sition is realized on high-permittivitysubstrate [8,9] due to the availability of better slotline models. However, a TSA performs best on low-permittivitysubstrate. On high- permittivity material, its performance is known to be poor unless parts of the substrate in the antenna are re- moved. This puts an extra effort on fabrication which has to be avoided when TSA arrays are involved [2,4]. An- other feed that can be considered is a transition from co- planar waveguide (CPW) to slotline. However, such a transition requires air bridges  which again add to additional fabrication effort.
DOI: 10.4236/ojapr.2018.63004 41 Open Journal of Antennas and Propagation dB due to the presence of highpermittivitysubstrate. This is the trade-off that has to be made in order to implement a smaller sized antenna at the same de- sired frequency. The future works involve multiband, broadband, mul- ti-polarization, and arrayed versions of these antennas.
There is a growing demand for compact microstrip patch antennas in the rapidly changing scenario of wireless and mobile communication to simultaneously access the multimedia information. The micro-strip antennas are low profile, comformable to planar and nonplanar surfaces, simple and inexpensive to fabricate using modern printed-circuit technology, mechanically robust when mounted on rigid surfaces, compatible with MMIC designs, and very versatile in terms of resonant frequency, polarization, pattern, and impedence. These antennas can be mounted on the surface of high performance aircraft, spacecraft, satellites, missiles, cars, and even handheld mobile telephones.
 Sadasivarao, B. and Madhav, B.T.P. 2014, "Analysis of hybrid slot antenna based on substratepermittivity", ARPN Journal of Engineering and Applied Sciences, vol. 9, no. 6, pp. 885-890.  Sreenivasa Rao, D., Lakshmi Narayana, J., K., Anil
mittivity. So, at first the phase response of the infinite substrate versus the variation of the electric permittivity is plotted and modeled with an equivalent circuit. Then, by implementing this phase curve and the effective elec- tric permittivity relation, the proper diameter and spacing of the holes at each element are calculated. Finally, the usefulness of the proposed structure and its performance are verified by two comprehensive examples. These ex- amples are simulated by the CST Microwave Studio TM package, which is based on the finite integration tech- nique .
Change of permittivity due to deformation. Both the parts of the relative permittivity decreased with increasing loading and at least partly these decreases were reversible during unloading parts of tests (Fig- ure 3a, b). The information about relative decrease of permittivity during the loading period is given in Figure 5a, c. This Figure shows that differences between both the tested varieties were not too high even the variety Nicola seems to be more sensitive to loading in most cases. The effect is stronger at the real part of the permittivity in comparison with the imaginary one. The sensitivity to loading also depended on current frequency but in different man- ner for the real and the imaginary parts: the relative decrease of real part of permittivity decreased with increasing frequency, whereas the opposite trend was observed at imaginary part.
array. Perforations create different effective dielectric permittivity and make the fabrication of the arrays feasible. The array is made from one piece of material; and inserting air holes with defined diameters and spacing in the required position. The perforations result in lowering the effective dielectric constant for the substrate at the region of air holes. The finite-integration technique, FIT  is used to calculate the characteristics of the reflectarray nanoantenna.
Cross polar radiation components are reduced by using polarisation dependent frequency selective surfaces. Circular polarisation is generated itself by FSS.  For satellite communication, the necessary requirements are wide bandwidth, high gain and circular polarisation. Patch array antenna are better option for increasing gain. Designing multiple feeds is difficult in FSS. -  Side lobes and back radiations are reduced by circular polarisation. Microstrip
pole resonant frequency. Using expression (1) and (2), and response on the EM-simulator, we can compute easily the unloaded Q-factor. It is 98 for our proposed loaded slot structure, whereas it is only 9 for the long rectangular slot. Thus the parallel plate with material loaded slot is a high Q compact resonator that also suppresses the spurious resonance of the unloaded slot resonator. It is a high Q-resonator with 91% increase in the unloaded Q-factor. The Q-factor can be further increase if we use low loss highpermittivity dielectric material in side the parallel plate capacitor. It will further reduce the size of the structure. It is suitable for rejecting the undesired narrow band signal. The high Q-resonator is suitable to improve the band rejection performance of the filter and the diplexer.
For storage and processing of tea moisture content sensing is necessary because it affects the quality and durability of the product. Oven method is time consuming technique. To overcome this problem moisture content measurement of oolong tea by equilibrium relative humidity technique used .Density-independent moisture content measurements can be applied on wheat within certain density ranges. Both Static and dynamic tests on wheat yielded the good results for density independent determination . Values of loss factors and dielectric constants are presented graphically for different products, i.e. grains, poultry products fruits and vegetables . Oilseeds and cereal grains permittivity varies with the frequency of electric field applied, and their temperatures, and bulk densities varies with the moisture content. . Researcher found the high correlation between moisture content and dielectric constant for each sample and was fitted data to quadratic trend line . Various factors such as frequency, moisture content, bulk density, temperature of food materials affect dielectric properties. Dielectric properties analysis and on-line measurement of food materials are portable, fast and inexpensive . The impedance of carrot samples at the end of the drying process reached higher values in comparison when samples had higher
Equation (37) relates the instantaneous response of the complex permittivity of the mixture in the time domain to the high frequency limit in the frequency domain. At high frequencies the charge movement (which creates the induced dipoles) is fast and can only be observed in a very short time window. When t = 0, the instantaneous response of the mixture is determined by the initial energy storage capacity (or charge accumulation) of the system. This is dominated by the permittivity of the suspending medium. As time goes on, the charges are set into motion by the external field, and the response of the system begins to be dominated by the conductivity of the system. This is a measure of the ease with which charge moves through a material .
In this paper, the complex permittivity of rubber latex is extensively characterised, for the first time, over the full microwave frequency range. The relaxation characteristics of rubber latex with different ambient temperatures and volume fractions are analysed. Knowing the microwave properties of rubber latex is an important step in the development of microwave sensors for determining the quality of rubber latex for agriculture and industrial application. Section 2 describes the experimental setup and conditions for the measurements. In Section 3, the complex permittivity of several rubber latex samples with different DRC percentages is presented, for different conditions, and the Cole-Cole plots as a function of temperature and DRC are obtained. In Section 4, the relaxation processes and activation energy of rubber latex are analysed using a graphical method. In Section 5, the extended Debye equations are applied to model the rubber latex permittivity behaviour.
source of the former one is a half-wave dipole, while the latter one is simply a plane wave. Analysis result shows that better radiation intensity can be achieved by choosing material with higher permeability to permittivity ratio, which is later confirmed by simulation results. Further measurement of material constants reveals that due to excessive permittivity values, a commercially available wave absorber is not an appropriate substrate when extensive reading range is desired. Based on the measured material constants, a metal tag is designed and fabricated based on composite material fill up with carbonyl iron powder, which demonstrates a 2.7 m read range with 2 mm thickness and miniature size.
its performance index on relationship between antenna resonant frequency shift and temperature variation with respect to the transmission line model . According to , the dielectric constant of the patch’s substrate and the physical dimensions are temperature dependent, which affects the resonant frequencies of the microstrip patch antenna. Also,  evaluated the effect of temperature on the resonant frequencies of microstrip patch antennas in order to adopt a microstrip patch antenna as a tempera- ture sensor. It has been observed that the temperature response of microstrip patch antennas leads to a simpler temperature sensor, inexpensive to produce and could be examined via wireless across a long distance. Hence ,  have validated the strain sensing capability of microstrip patch antennas and temperature sensing capa- bilities enabling temperature compensated strain measurements resulting in a robust wireless antenna strain sensor at varying environmental conditions.
respectively. The simulation results with these materials show a substantial gain improvement of up to 11.5 dB (Fig. 3). A linear relationship among the different materials could be established if the lossy FR4, alumina and Roger 3210 substrates are excluded from the analyses. The gain drop as the dielectric constant of the substrate increases is equivalent to 2 dB per decade.
Microstrip antennas are in greater demands in wireless communication and space applications because of small size, low weight. The microstrip antennas possess the shortcomings such as narrow bandwidth, low gain and poor efficiency . These shortcomings can be overcome by using multilayered rectangular microstrip antennas. This can be achieved by proper combination of the substrate and superstrate thickness over and under the patch. Multilayer Microstrip patch is also useful to provide protection to patch from heat, rain, physical damage, and naturally formed ice layers during flight . There are many methods available in the literature to calculate the resonant frequency of multilayered rectangular patch based on numerical technique . None of the efficient analytical model is available in literature related to multilayered structure to obtain the antenna dimension. There are mainly four techniques for enhancement of Bandwidth of given Microstrip Patch Antenna. Which are, multilayered configurations of Broadband Microstrip patch antenna, Stacked Multiresonator Microstrip patch antenna, Modified Shape Patch Broadband Microstrip patch antenna, Planar Multiresonator configuration of Broadband Microstrip patch antenna, in multilayered configuration patches are placed over different dielectric substrates and they are stacked on each other. Based on the coupling mechanism, these configurations are of two types electromagnetically-coupled or aperture-coupled. There are mainly two method of coupling to multilayered antenna, Electromagnetically-coupled Technique and Aperture-coupled Technique. In Stacked Multiresonator Microstrip patch antenna configuration multiresonator and stacked configurations are combined to provide broadband microstrip patch antenna. This antenna is applicable for wireless communication such as WLAN. A single line feed stacked microstrip antenna for 4G system is presented and performance of proposed antenna improvement of bandwidth 15% .