CAD for CATV design

Software packages for the design of cable TV networks and created by different firms and companies were examined and analyzed by functional abilities and application areas. Examples of CATV network design are give

Rectangular waveguide resonators in planar form for filter applications

The paper observes microwave waveguide resonators in planar form and proposes a design for obtaining low-cost devices in planar form that are suitable for mass fabrication. Periodic resonators at 3.6 GHz are designed and simulated using this technique, which represents the advantages of this technology, resulting in the reduced size, cost and compactness of these components, while maintaining an easy fabrication process. This is achieved due to the configuration that holds both the microstrip and the rectangular waveguide interconnected by a simple taper on the same substrate

CAD for broadband wireless access design

The paper looks at the multifunctional and specialized CAD systems of leading companies for use in the field of broadband wireless equipment design. The basic characteristics of appropriate software and design systems are shown including the most typical examples for their implementatio

Minimizing memory effects in OFDM transmitters using adaptive baseband equalization

This paper presents a simple and effective approach for eliminating memory effects in OFDM transmitters. It uses advantages of OFDM systems to provide pre-compensation of the frequency-dependent distortions, which are results of the power amplifiers (PA) memory effects. The process of memory effects quantification is carried out in this paper by obtaining a frequency-dependent PA gain, phase shift and intermodulation products. The memory effects are eliminated at baseband using equalization of the IDFT signal. Implementation of the equalization procedure at baseband makes the process of minimizing memory effects simple and effective, because no additional RF components or feedback loops are used. Memory effects are compensated in DSP part using simple multiplication of the frequency-domain digital signal by coefficients, which are calculated adaptively for each OFDM sub-carrier frequency and input power. The approach is tested with Motorola MOSFET MRF9742 power amplifier model in Advanced Design System (ADS). Simulations show significant improvement in minimizing memory effects. Received constellation of the 16-QAM OFDM signal after implementing baseband pre-compensation technique looks alike ideal one, whereas without pre-compensation it shows high dispersion due to the presence of PA memory

Linearization of power amplifiers by baseband digital predistortion for OFDM transmitters

For the signals with high peak-to-average ratio (PAR), such as WiMax OFDM, power amplifiers need to operate in a compression mode. It results in a non-linear distortion of the output signal. To compensate for this distortion, linearizers are used. However, they decrease efficiency of amplifiers. This paper proposes to use a digital predistortion of baseband signals, which is characterized by a small impact on efficiency and a good linearizing performance, for linearization of OFDM transmitters. The paper describes design of a baseband predistorter and verifies its performances by WiMax OFDM simulations in ADS. Proposed predistorter brings significant improvements in AM/AM characteristic, eliminates spectrum re-growth, decreases adjacent channel power ratio (ACPR) and error vector magnitude (EVM)

Novel compact substrate integrated waveguide resonators at 60 GHz for LCP

In this paper a new approach to design of compact substrate integrated resonators is presented. LCP substrate integrated waveguide is loaded by array of multilayer metallic plates situated inside the substrate. Resonators are designed and simulated with a resonant frequency of 60 GHz. Proposed structures are twice more compact than their conventional substrate integrated counterparts

Novel SRR loaded waveguide bandstop filters

Two types of novel split ring resonator (SRR) loaded rectangular waveguide bandstop filter structures have been presented. The first proposed SRR-loaded waveguide bandstop filter has been designed simulated and tested. Using the combination of the split ring resonators, conductive wireline and transversely placed metal septa, the composite material has been built and inserted into the hollow rectangular waveguide to form an SRR-loaded waveguide unit. The bandstop filter has been constructed by cascade of the two resonator unit cells. The second proposed multilayer SRR loaded waveguide bandstop filter has been designed and simulated. Three transverse periodic SRRs are present on either side of the dielectric blocks

A new approach for non-linear analysis of power amplifiers

This paper presents a new approach for non-linear analysis of power amplifiers based on the n-order polynomial modelling. A general expression for the fundamental frequency output is developed in this paper. It allows considering any order of polynomial model and obtaining analytical expression for the fundamental-frequency output without complex computations, using developed formulas. This model significantly simplifies non-linear analysis of power amplifiers and the process of designing linearizers. This paper also presents a simple approach for obtaining polynomial model from a frequency response of power amplifier. The proposed method is verified by experiments. Obtained polynomial model shows simulation results similar to the measurements for real amplifier. Developed n-order output modelling and proposed model extraction method can significantly simplify, optimize and enhance power amplifiers’ non-linear analysis and behavioural modelling. Proposed modelling approach can be also used to design linearizers

Ridged waveguide manifold multiplexers with improved performance

This paper demonstrates the bandwidth improvement of a multiplexer overcoming the limitations imposed by the poor stopband performance of standard waveguide E-plane filters. Bandwidth improvement is achieved by introducing an integrated compact ridge waveguide filter in the multiplexer. A four-channel X-band ridged waveguide manifold multiplexer is used as an example. Electromagnetic modelling of the multiplexer and experimental verification of an integrated ridge waveguide filter are presented