The reflection and absorption properties of powdered nanocrystalline FeSiBCuNb (“Finemet”) alloy at microwaves have been presented. To visualize the shielding ability of this material, the complex permittivity and permeability of pulverized Finemet in the frequency range from 0.2 to 10 GHz have been studied. To measure the permittivity and permeability of powdered Finemet, the modification of the Nicolson, Ross, and Weir method was presented. The modification of this method was mainly based on the unwrapping technique of the measured S-parameter phases. The investigation of permittivity and permeability was realized for pure powders. Four groups of powders with different particle sizes below 200 μm have been investigated. To assess the shielding effectiveness of the nanocrystalline Finemet, two attempts were analyzed. The investigation of the reflection loss of material layer with metal sheet attached to the backside as a reflector was investigated. On the other hand, the reflection and absorption factors of 3-mm-thick layer in free space were additionally analyzed. The obtained results show that the pulverized nanocrystalline Finemet alloy with particle size below 25 μm possesses good absorption properties and, for such particles, the absorption factor is significantly higher than the reflection factor.

In urban environments, a multipath propagation and the Doppler effect are dominant phenomena that negatively affect the quality of service in wireless communications and realization of location methods. This paper presents the localization method of emission source in urban terrain for NLOS conditions based on the Doppler effect. To this aim, authors use the signal Doppler frequency (SDF) method. For mobile receiver locates and stationary transmitter, a spectrum of the received signal, called also the Doppler spectrum, is spread. On this basis, the estimation of the Doppler frequency shifts are used in SDF. In the paper, authors present a novel simple method of this estimation. Evaluation of SDF accuracy are obtained on the basis of simulation studies. The Doppler multi-elliptical channel model is used to the wireless channel modeling. In performed analysis, relative errors of transmitter location are in the order of single percent. Presented method can be easily used to PSK, OFDM and other emissions that have a harmonic in the signal spectrum.

Satellite navigation is now widely used in a land, sea, and air transport. It is easy to forecast the negative effects related to the lack of a signal of the Global Navigation Satellite System (GNSS), especially in the aviation and maritime traffic. In 20th century they were allayed the terrestrial navigation systems, e.g. Decca, Omega, Loran-C. Recently, only eLoran is used, as a backup system for GNSS. The Polish Defense Ministry plans to develop a new navigation system that should provide positioning data for the Polish Navy ships that will carry out combat missions in coastal areas, regardless of GNSS. This paper presents the concept of a reserve navigation system (RNS) that is based on the signal Doppler frequency (SDF) location method. Effectiveness of RNS is shown on the basis of simulation studies. Obtained results indicate the possibility of the vessel positioning on the basis of signals from one or more radio beacons of the system.