Passive Prototypes Research Articles

Sustainable Design Methods Translated from the Thermodynamic Theory of Vernacular Architecture: Atrium Prototypes

In the context of China’s sustainable development and dual carbon goals, research on thermodynamic architecture theory and vernacular architecture increasingly aligns with international trends, developing distinct characteristics. This research addresses the challenge of rapid changes in the built environment by focusing on climate adaptability and passive technologies. However, the development of thermodynamic theory in vernacular architecture faced technical limitations in the early 21st century and was later overshadowed by the industry’s reliance on active technologies to meet green building standards, resulting in a reduced role for architects in the green building field. This article traces the origins of passive architecture, rooted in vernacular architecture, and applies thermodynamic theory to explore architectural prototypes. It examines the theoretical feasibility of architectural design in achieving low-carbon and sustainable goals, aiming to fill a gap in thermodynamic theory within the broader context of sustainable architectural development. After demonstrating the various passive prototypes inherent in vernacular architecture, this paper proposes a courtyard prototype focused on residential comfort for design translation and analysis. The research methods employed include bioclimatic charting, balance point temperature analysis in time series, and extensive computer simulations. Through the process of prototype extraction, performance analysis, validation, and optimization, the paper systematically discusses sustainable design methods within the framework of thermodynamic architecture theory. It also provides practical demonstrations of these methods across four distinct climate regions in China. By translating vernacular architectural designs, this research systematically organizes the theoretical framework for architects’ early involvement in low-carbon and green building design, offering a theoretical foundation for initiating the design process through prototype translation while guiding the generation of green ecological buildings.

Low-Cost Wide-Angle Beam-Scanning Transmitarray Antennas Using Lens-Loaded Patch Elements: A Proof-of-Concept Study

In this letter, a novel design concept to achieve a low-cost wide-angle beam-scanning transmitarray (TA) using lens-loaded patch (LLP) elements is presented. In this design, each TA element consists of a beam switchable transmitting element, a group of receiving elements, and a signal via. The received powers of a 2×2 subarray are first combined and then transmitted to the corresponding LLP element, where the phases of the transmitted signals are manipulated for beamforming. Compared with the conventional designs, the phase shifters (PSs) can be multiplexed and the number of PSs is effectively eliminated by 75%, which significantly decreases the hardware cost. By employing multiple patches as the feed of the lenses, reconfigurable radiation patterns are obtained, and by properly choosing the transmitting patches, the developed TA achieves a wide-angle two-dimensional beam scanning within ±60° with stable gains. To validate the design concept, passive prototypes with a center frequency of 12.5 GHz are simulated, fabricated, and tested. The measured results show that the aperture efficiency is 30.1%, 19.4%, and 14.1% for beams steered to 0°, 30°, and 60° at 12.5 GHz, respectively. The beam coverage of ±60° with a less than 3.5 dB scanning loss in the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">H</i> -plane is obtained.

Proof of Concept of a Low-Cost Beam-Steering Hybrid Reflectarray that Mixes Microstrip and Lens Elements Using Passive Demonstrators

In this article, a proof-of-concept study on the use of a hybrid design technique to reduce the number of phase shifters of a beam-scanning reflectarray (RA) is presented. An extended hemispherical lens antenna with feeds inspired by the retrodirective array is developed as a reflecting element, and the hybrid design technique mixes the lenses with the microstrip patch elements to realize a reflecting surface. Compared to the conventional designs that only use microstrip antennas to realize a reflecting surface, given a fixed aperture size the presented design uses 25 percent fewer array elements while shows comparable beam-steering performance. As a result of using fewer elements, the number of required phase shifters or other equivalent components such as RF switches and tunable materials is reduced by 25 percent, which leads to the reduction of the overall antenna system's complexity, cost, and power consumption. To verify the design concept, two passive prototypes with a center frequency at 12.5 GHz were designed and fabricated. The reflecting surface was fabricated by using standard PCB manufacturing and the lenses were fabricated using 3D printing. Good agreement between the simulation and measurement results is obtained. The presented design concept can be extended to the design of RAs operating at different frequency bands including millimetre-wave frequencies with similar radiation performances. The presented design method is not limited to the microstrip patch reflecting elements and can also be applied to the design of the hybrid RAs with different types of reflecting elements.

Topological emulation of continuous-time passive prototypes using wave port adaptors

A novel systematic method for designing high-order wave active filters is proposed in this study. This is based on an appropriate description of both the behaviour of passive elements and the topology of the prototype filter using the wave variables. The fulfillment of the Kirchhoff&apos;s laws is achieved by employing wave port adaptors. The proposed realisation of the topological emulation of prototype filter is performed using current-mirrors as active elements. This is originated from the fact that summation/subtraction and scaling operations are required for the realisation of wave port adaptors. An attractive characteristic of the proposed method is that the derivation of high-order filters is a one-step procedure because of the availability of the wave active equivalents of passive elements and adaptors. A third-order elliptic filter has been designed in AMS 0.35 µm CMOS process and its performance has been evaluated and compared through simulation results.

Principles and applications of a controllable electromagnetic band gap material to a conformable spherical radome

This paper presents the principle of two types of conformable and controllable spherical radome based on Electromagnetic Band Gap (EBG) materials operating at around 10 GHz. The EBG structure is composed of a grid of metallic wires conformed on a hollow spherical object. Two switching control configurations are considered: (1) between an EBG structure made of electrically continuous wires and another one made of discontinuous wires, and (2) between two EBG structures made of discontinuous wires where each has a different period of discontinuities. Both switching configurations are simulated and experimentally characterized on passive prototypes. An excellent agreement is observed between simulations and measurements. The radiation patterns of two types of antennas, a horn antenna and a meteorological antenna, are also measured in the presence of the radome.

Systematic derivation of explicit design formulae for log-domain: A 3rd-order lowpass example

The operational simulation of passive prototypes in log-domain is feasible either by means of state-space-based techniques or by transforming the SFG corresponding to the linear prototype. However, the correlation of the prototype element values with circuit parameter (i.e. capacitor and biasing current) values constitutes a synthesis step, which is not explained in detail by the available literature and usually entails a considerable amount of expertise. This paper aims at elaborating one possible way of such an explicit correlation by means of the concept of the Intermediate Transfer Function. An exemplary 3rd-order LP ladder Chebychev response is synthesised and analytic design relations are systematically derived.The resulting general formulae allow the engineer to explore several possible design freedom parameters as far as the filter topology selection and its performance are concerned. HSPICE simulation results are provided.

Log-domain filtering by simulating the topology of passive prototypes

A systematic method for designing log-domain filter structures that simulate the topology of the corresponding passive prototypes is introduced in this paper. This has been achieved by transposing the i-/spl upsi/ characteristic equation of each passive element in the linear domain, to the corresponding one in the log domain. The transposition has been done in such a way that, the current that flows through the terminals of the passive element in the linear domain sustains its value in the corresponding log-domain configuration. In this way the linear operation of the whole filter is preserved. With regard to the voltage at each terminal of the passive prototype, this is logarithmically compressed in order to achieve filtering in the log domain. Following the above considerations, the log-domain equivalents of all passive elements of the prototype filter were derived. Having established the equivalents, the procedure for designing high-order log-domain filters is quite facilitated. The validity of the proposed technique is demonstrated through simulation results for a fifth-order elliptic low-pass filter.

ActiveRC impedances revisited

The aim of this paper is to review the synthesis, analysis and design of active RC impedances. First of all, major gaps in this classical research topic are identified. Second, a synthesis procedure is outlined to generate op-amp-based circuits which can simulate several classes of impedances of practical interest. From the resulting classification, all circuits are analysed from a perspective wider than those normally used in previous works, yielding some new interesting design conditions. A method is suggested to convert ladder passive prototypes containing either grounded inductors or FDNRs into MOSFET-C equivalent circuits using some of the new structures obtained. Finally, the use of current feedback amplifiers instead of op amps is considered. Experimental results corroborating all our theoretical predictions are incorporated in the work. © 1997 John Wiley & Sons, Ltd.

High frequency compensated current-mode ladder filters using multiple output OTAs

A methodology to implement compensated current-mode filters using multiple output OTAs and based on RLC ladder filter prototypes is presented. The resulting structures are very compact and share the low sensitivity characteristics of the passive RLC prototypes. They can be realized as CMOS circuits since they use only grounded capacitors and OTAs with one of the input terminals grounded. Compensation techniques to minimize degradation in the filter response due to excess phase of OTA parasitic poles are discussed. Simulations with CMOS OTAs and experimental results from discrete circuit implementations using bipolar OTAs are presented that verify the proposed approach. >

An improved method for the evaluation of filter sensitivity performance

Conventional sensitivity measures are unsuitable to evaluate filter performance. They ignore the difference between ripple increase (a serious degradation of filter performance), and the flat-gain deviation (of much less practical importance). These two aspects of filter performance are taken into account separately in the multiparameter sensitivity indexes proposed in this paper. The new indices are applied in a comparison of active filters obtained by different methods of simulation of passive ladder prototypes.

Novel voltage inverter switches with minimum sensitivity properties

A class of switched-capacitor (SC) filters using voltage inverter switches (VIS's) with minimum sensitivity properties is proposed. The novel realizations use only fully stray-eliminating (usually referred to as stray-insensitive) SC circuits and offer a true one-to-one correspondence between the elements of the reference filters and the network capacitors of the corresponding SC circuits. Thus the transfer functions of the proposed SC filters depend only on the matching properties of the network capacitors if the open-loop gain of the required operational amplifiers is sufficiently high. In this way the excellent sensitivity and noise Performance of the underlying passive prototypes are retained.

Switched capacitor filters for a 1200 baud FFSK modem

The design of two 8th order switched capacitor filters for anFFSKmodem is described. The response of the filters in the passband is not made flat, in order to optimize the signal to noise ratio of the transmission channel. The design of passive prototypes and the criteria for the choice of the best passive and active topologies are described. Computer simulation results of the performances of the SC filters are given.

Bilinear design of fully differential switched-capacitor ladder filters

Fully differential switched-capacitor (SC) analogue blocks are shown to be suitable for implementing SC ladder filters via the bilinear transform of the corresponding analogueRLC passive prototypes. These filters become fully insensitive to parasitic capacitance effects, while the interesting features of the differential implementation, i.e. power supply and common mode rejection ratios and dynamic range improvements, are retained. The technique presented is useful for the exact design of wide-band SC filters, i.e. for filters with a small ratio between the clock frequency and the cut-off frequency. As an example, the bilinear design of an 8th-order Cauer bandpass filter is given, with numerically computed results.