Impedance network boundary conditions (INBCs) are implemented in the finite-difference time-domain (FDTD) method to analyze the electromagnetic field around penetrable shield structures. The shield region is eliminated from the computational domain and the INBCs are applied on the new boundary surfaces, i.e., shield surfaces, to take into account the field discontinuity produced by the shield. The INBCs represent an important extension of the well-known surface impedance boundary conditions (SIBCs) since the INBCs model accurately the coupling of the electromagnetic fields through penetrable shields and lead to a significant reduction of the number of the FDTD unknowns. The INBC expressions are given analytically in both frequency and time domains, and the INBC implementation in a FDTD code is discussed. The proposed INBC-FDTD method is numerically efficient because the resulting convolution integrals are recursively solved. Furthermore, approximate time-constant INBCs are proposed which are valid for many practical applications. The analysis of transient electromagnetic fields around penetrable conductive shields in simple test configurations are presented and compared with the analytical solution
This paper proposes a wideband dual-polarized slot-coupled stacked patch antenna operating at UMTS, WLAN (2.4 GHz) and UMTS II frequency bands. The antenna has been designed and optimized by using Ansoft Designertrade. A prototype has been realized and measurements were carried out showing good performance in the whole required bandwidth (33.4% bandwidth
the sub-surface object cannot be distinguished. The input reflection characteristic of the PDTEMA is pretty good and VSWR less than 2 with an average value of 1.5 is clearly attainable over the 50:1 frequency band, as shown in Figure 10. Thus, the input impulse reflection levels of about 0.15 can easily be achieved for 1 GHz sub-band and 10 GHz full-band transformations (see Fig. 11). It should be noted that due to the internal (ϳ100 ⍀) loads of the 2-ways splitter, there is no need extra resistive loadings at feed gaps or antenna apertures to compensate VSWR for lower frequencies.
CONCLUSIONIn this study, the partial dielectric loaded TEM horn array antenna was proposed for hyper wide band impulse radars and multi-band GPR systems. The modified PLTLM algorithm, which is based on combined transmission line modeling approach, has been used to simulate the PDTEM horn array designs fast and reliable. The simulation results were compared with MoM and obtained adequately good agreement. The gain and VSWR characteristics of the PDTEMA were measured from 50 MHz to 10 GHz comparing with calibrated LP and ridged horn antenna models. It was shown that the PDTEMA attains highly efficient impulse radiation performances for ultra broadband radar applications and suitable for multi-band GPR operations.
In this paper, three different configurations of planar antennas with a 100 Omega differential input impedance for dual-band WLAN applications, have been designed and compared. The proposed antennas provide dual-band operation in the 802.11a/b/g frequency bands without using a balun (balanced feeding). The best return loss performance has been obtained with the dual-band printed dipoles which are also characterized by a relatively straightforward design and tuning procedure. Measurements on constructed prototypes are shown at the conferenc
In this paper an optimization of the set-up for the shielding effectivcwiass measurement of a closed thin enclosure is shown, Various sort of noise, due to the measuring set-up, can superimpose to the signal o r interest, making difficult to recover it from what is received by the instruments.A complete analysis of the problems that arise in the case of ESD, CW conducted and CW radiated excitations is presented, together with their solutions.
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