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This article presents a novel concept for a highly accurate and simple two-port vector signal analyzer. A current phase ratio measurement method is defined for one independent external signal with a restriction of the measuring range ±90 or ±180°. The article presents a new way of phase ratio evaluation of two independent external signals with precise phase determination in a wide range from 0° to 360°. The new functional blocks of the analyzer circuit element act as a four-position radio frequency (RF) switcher and an algorithm for phase determination is presented. Practical application and verification of the results achieved are demonstrated by measuring the phase directional radiation pattern of a complex object such as an aircraft fuselage.

The aircraft avionics modernization process often requires optimization of the aircraft itself. Scale models of aircraft and their antennas are frequently used to solve this problem. Here we present interesting properties of the resonant antennas, which were discovered serendipitously during the measurement process of some microwave antennas’ models as part of an aircraft modernization project. Aircraft microwave antennas are often designed as non-symmetric flat microwave antennas. Due to their thin, low and longitudinally elongated outer profile, they are also called tail antennas. An analysis of the resonant properties of non-symmetric antennas was performed in the band from 1 GHz to 4 GHz. The length of the antenna models ranged from 2 cm to 7 cm. The width of the antennas, together with the thickness of the strip, was always a constant parameter for one measured set of six antennas. In the measurement and subsequent analysis, attention was focused on the first-series resonant frequency (λ/4) of each antenna. During the evaluation of the resonance parameters, the flat microwave antenna models showed specific resonant properties different from those of conventional cylindrical microwave antennas. This article aims to inform professionals about these unknown specific properties of non-symmetrical antennas. The results of experimental measurements are analyzed theoretically and then visually compared using graphs so that the reader can more easily understand the properties observed. These surprising observations open up some new possibilities for the design, implementation, and use of flat microwave antennas, as found in modern aircraft, automobiles, etc.

Presented paper concentrates on accidentally identified, specific method of mechanical vibration demodulation, radiated high-frequency signal of aircraft communication antenna, located directly on the aircraft. It describes the structure and solution of the designed laboratory workplace at which it is possible to evoke mechanical vibration demodulation as a specific phenomenon. The aim is to analyze possible physical electric characteristics of antenna as a source of mechanical vibration on “Monopole“ type of antenna. Next, transfer amplitude frequency characteristics of the antenna, as a mechanical vibration demodulator, are analyzed. As this is a basic research of this accidentally identified phenomenon, an observation method of experiment results is used to find out the analogies by the form of their comparison with a classical amplitude demodulator. The results show that if the mechanic influence of artificial ground is suppressed, the transfer amplitude frequency characteristics of such demodulated signal has minimal distortion in frequency range 200Hz to 3.5kHz. The paper presents brief summary of measured basic values on the base of which obtained results are analyzed and brief conclusions of observed phenomenon are defined. They are the first outputs of the phenomenon observations on the base of which it can be concluded that it is reasonable to deal with this problem. At the same time this is not just the antenna characteristics analysis but also the analysis of mechanical oscillations of the antenna from the viewpoint of its more secure fixing at the aircraft fuselage. Because the concurrent influence of two kinds of vibrations, primary – as a result of aerodynamic circumfluence of antenna during the flight in collaboration with the secondary – as a result of its radiation, places higher requirements on its mechanical fixation. Presented facts mean the increase of air traffic operation.

Each vehicle antenna has a variety of electrical and mechanical properties that characterize it. Each one of the considered series of features evaluates the antennas from a different point of view. The electrical properties of antennas are characterized by its various energy, impedance and radiation parameters. The radiation parameters of the antenna can be objectively assessed according to the shape of its radiation - directional characteristics. The shape of the directional characteristic of the antenna is influenced by a number of interrelations between its electrical and mechanical properties. The best known relationship that affects the shape of the directional characteristic of the antenna is the ratio between its mechanical parameter - the antenna length “l” and the electrical parameter - the wavelength “λ” of the operating frequency. In the theory of antennas, it is a known ratio “l / λ”, which determines the shape of the directional characteristic of the antenna. This ratio, which shapes the electric current distribution on the antenna, can be evaluated or simulated relatively simply (but not exactly), but in practice it is very difficult (almost impossible) to measure it. The article deals with a specific approach to objective practical measurement of electric current distribution on a linear antenna in the VHF frequency band.

This article describes the design and implementation of a low-profile sinuous slot antenna, intended for ultra-wideband (UWB) sensor networks, which can be produced on one conductive layer. The article explains the design and optimization of the sinuous slot antenna and its modifications, including its sinusoidal curve shape. Other modifications were aimed at optimizing the antenna feeding. Desirable properties of the designed and implemented antenna modifications were verified both by simulation and empirically. Experimental measurements of the antenna&rsquo, s properties were carried out using a vector network analyzer in an anechoic chamber and also by a pulsed UWB radar in the frequency range from 0.1 to 6 GHz. The low-profile antennas were implemented on a Rogers RO3206 substrate.

In our laboratory, we developed a simple estimation of the wall thickness by the UWB (Ultra Wide-Band) radar system. The described technique measures the wall thickness in the two steps. The first step is a measurement of the wall relative permittivity. The second step is a reflections localization and estimation of the wall thickness. The borders of the wall could be detected by the envelope of the received signals. The described technique calculates the signal envelope by the Hilbert transform. Moreover, the relative permittivity of the wall is estimated by the technique developed in our department as well. The effective relative permittivity is calculated from the frequency dependency of relative permittivity.

We suggest a conceptual approach to the measurement of the near-surface wind vector over water using a Doppler navigation system, in addition to its standard navigation capabilities. We consider a Doppler navigation system with a track-stabilized antenna and x-configuration of its beams. For the measurement of the sea-surface wind, the system operates in the multi-beam scatterometer mode in rectilinear flight. The proposed conceptual design has been validated, and its accuracy for the wind vector measurement has been estimated using Monte Carlo computational simulations.