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This paper describes application of the Surface Integral Equation - Method of Moment (SIE-MoM) approach to the analysis of scattering by different structures inside uniform waveguides and cavities. We show convergence characteristics of infinite double series related to different reaction integrals, i.e. the elements of the MoM matrix. We also demonstrate correctness and effectiveness of the implemented...
The case of improving bandwidth of planar patch antennas is investigated. More specifically, the analysis deals with slot-loaded patch antennas. The use of a combined feeding apparatus capable of providing ‘reactance-balance’, and thereby improving bandwidth, is presented. The effectiveness of this simple technique in achieving nearly 35% fractional bandwidth is demonstrated using experimental measurements.
The present publication describes an innovative concept for fawn saving during pasture mowing in spring time. Conventional approaches like scaring by dogs or scarecrows are ineffective and time consuming especially for large areas. Other technical solutions have different drawbacks or insufficient search performance. Within the active UHF RFID localization system the processes of identifying fawns...
This paper presents the design of a linear antenna array for use in a 24 GHz radar tachymeter. The task of the proposed radar tachymeter is the precise measurement of the distance and angle to a cooperative transponder. To obtain the desired high accuracy, we designed an optimized sparse antenna array. The antenna pattern was selected using a brute-force optimization method. A fixed number of array...
Mitigation of wind turbine interference (WTI) requires modelling of its impact on radars, navigation systems and terrestrial radio links. A proper analysis of this interference by numerical field simulation, in particular including the effect of diffraction, requires a high computational effort as the problem is electrically extremely large. We propose a 2D Fresnel diffraction approach applied to...
In this paper a detailed investigation of LNA noise using negative transformer feedback matching is performed. It is shown, that the transformer matching technique (TMT) is well suited for full on-chip integration of the necessary inductors and it also enables a low noise figure while conjugate complex matching is performed. To prove the assumption analytical calculations using a simplified VBIC-transistor...
This paper presents a novel concept for a planar cross-polarized transition to a 61 GHz dielectric lens antenna. The transition to the circular waveguide antenna feed consists of a combination of a microstrip line and a slot line. Each of these planar waveguides excites the H11 mode in the circular waveguide with a 90± polarization angle to one another. The developed double layer transition topology...
A wideband, body contact, directive beam, circularly polarized, single arm, Archimedean spiral antenna for radiometric temperature measurement inside a human body in S-band and an SAR (specific absorption rate) measurement method using a thermal camera are described in this paper. A new approach of designing the spiral antenna based on using the estimated effective permittivity of a multilayered microstrip...
This work adresses the temperature dependence of tunable components based on inkjet printed low temperature sintered Barium-Strontium-Titanate (BST) thick-film layers. To evaluate the temperature dependence, metal-insulator-metal (MIM) parallel-plate capacitors were fabricated and characterized over a temperature range between −60°C and 100°C. A relative capacitance shift below 8.3% was measured in...
This paper presents a method to compensate CMOS process-, voltage-, and temperature (PVT) variations in a linear two-stage RF power amplifier (PA). The proposed circuit technique mitigates bias point fluctuations caused by non-controllable uncertainties like wafer-dependent electron mobility, increasing die temperature due to substrate self-heating, or supply voltage deviations. A scaled PA replica...
A wideband 1∶7 radial power divider for operation at K-band is proposed. The divider features a radial substrate integrated waveguide (SIW) cavity enclosed in a multilayer printed circuit board (PCB) as well as microstrip matching structures and feed-lines on the top and bottom layers. The divider is designed using standard high-frequency substrate. Including the outer vias, the divider cavity has...
This paper presents a 3-dB coupler providing 90° output phase-difference over wider bandwidth compared to other single-stage planar couplers. The proposed design is suited for the applications where high power RF signals need to be combined with quadrature phase. It uses a symmetric rat-race coupler to achieve wider bandwidth as compared to its asymmetric counterparts. The proposed coupler has a measured...
Concept, design equations, implementation and applications of dual-band immittance inverters based on a dual-composite right/left-handed transmission line (D-CRLH) TL are considered. The proposed immittance inverters with a stop band between the frequencies of operation are shown advantageous for applications in dual-bandpass filters to provide a high rejection between the pass bands.
In this paper, a novel electromagnetic bandgap (EBG) structure has been introduced. Initially, the EBG is theoretically analysed using a lumped element model. Thereafter the dispersion diagram of the EBG is extracted by simulating the EBG unit cell in eigenmode Solver of CST Microwave Studio. The simulated bandgap values shown by the dispersion diagram are then experimentally validated by using a...
The signal-to-noise ratio (SNR) of the analog-to-digital converter (ADC) typically limits the sensitivity of wideband receivers for Software Defined Radio (SDR) or Cognitive Radio (CR) applications in the presence of a strong interfering signal. A Stacked ADC configuration—two or more parallel ADCs, each with a different drive level—promises an increased dynamic range of the analog-to-digital interface...
The accuracy of trajectory measurements is one of the crucial factors in high-resolution SAR imaging. Common navigation systems often do not fulfill the requirements that results in significant image quality degradation. In the paper, a new autofocus algorithm for the reconstruction of the SAR platform trajectory deviations is proposed. The approach is based on the estimation of the Doppler rate errors...
This paper presents a new frequency adjustable Ka Band Cross-Guide coupler for space applications. Up to now Cross-Guide couplers were designed for a fixed frequency range and tuning screws were used to compensate fabrication tolerances. This work utilizes the tuning screws not only to correct fabrication tolerances but also to adjust the frequency of operation. The design strategy and test of the...
A highly sparse array based on combining multiplicative processing and Difference Pattern Processing (DPP) is presented. A thinning rate of more than 80% is demonstrated for a Step Frequency Continuous Wave Range Radar (SFCWRR) composed of a filled- and a highly thinned subarray in a cocentered configuration. The high resolution is achieved with the correlator whilst low spurious signal suppression...
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