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Micro-Spec (μ-Spec) is a direct-detection spectrometer which integrates all the components of a diffraction-grating spectrometer onto a ∼10-cm2 chip through the use of superconducting microstrip transmission lines on a single-crystal silicon substrate. A second-generation μ-Spec is being designed to operate with a spectral resolution of 512 in the submillimeter (500-1000 μm, 300-600 GHz) wavelength range, a band of interest for several spectroscopic applications in astrophysics. High altitude balloon missions would provide the first test bed to demonstrate the μ-Spec technology in a space-like environment and would be an economically viable venue for multiple observation campaigns. This work reports on the current status of the instrument design and will provide a brief overview of each instrument subsystem. Particular emphasis will be given to the design of the spectrometer's two-dimensional diffractive region, through which the light of different wavelengths is focused on the detectors along the focal plane. An optimization process is employed to generate geometrical configurations of the diffractive region that satisfy specific requirements on spectrometer size, operating spectral range, and performance. An optical design optimized for balloon missions will be presented in terms of geometric layout, spectral purity, and efficiency.

The tendency over the last decades in the aerospace industry is to substitute classic metallic materials with new composite materials such as carbon fiber composites (CFC), fiber glass, etc., as well as adding electronic devices to ensure the safety and proper platform operation. Due to this, to protect the aircraft against the Electromagnetic Environmental Effects (E3), it is mandatory to develop accurate electromagnetic (EM) characterization measurement systems to analyze the behavior of new materials and electronic components. In this article, several measurement methods are described to assess the EM behavior of the samples under test: microstrip transmission line for a surface current analysis, free space to obtain intrinsic features of the materials and shielding effectiveness (SE) approaches to figure out how well they isolate from EM fields. The results presented in this work show how the different facilities from the National Institute of Aerospace Technology (INTA) are suitable for such purposes, being capable of measuring a wide variety of materials, depending on the type of test to be carried out.

A mutual coupling reduction method for closely installed patch antenna (PA) and microstrip transmission line (MTL) is proposed by means of defected isolation wall structure (DIWS) which is comprised of a metal patch with periodically G-shaped structure and two dielectric substrate sheets set on both sides of the metal patch. The DIWS model, design procedure and investigation on its stop filtering characteristics are presented. Also, the dominant parameters of DIWS are discussed in order to flexibly adjust the stop band to meet the frequency band that we are interested in. Finally, the optimized DIWS is installed on the closely set PA and MTL with a distance of 2 mm to suppress the mutual coupling. The proposed structure is fabricated and measured to verify the simulation results which demonstrated that a high isolation of 27 dB and 37 dB between the antenna and MTL are achieved, respectively.

At the C-band, a double-layer series-fed linear array antenna is proposed. T-shape and interdigital microstrip transmission lines are used to increase the impedance bandwidth and obtain a reduced sidelobe level (SLL). The antenna has a bandwidth (BW) of 28% (VSWR ≤ 2), a SLL of −20 dB and a gain of 13.5 dB across the BW of 23%. Details of the antenna design and the experimental results are presented.

In this paper, we consider a technique for extracting parameters that allows calculating nodes taking into account the properties of the material used in the technology of printer printing. As a result of the extraction of parameters, the real parameters of the material were revealed. At 1 GHz, the loss of a 20 µm microstrip line is 12 dB/m. With a threefold increase in thickness, the losses decreased to 7 dB/m.

A low-cost, reduced-size, single-feed, single-layer microstrip patch antenna is presented that receives right-hand circularly polarised satellite signals for the global positioning system's L1-Band (1575.42 MHz) and left-hand circularly polarised satellite signals and vertically linearly polarised terrestrial signals for the satellite digital audio radio system band (2320–2345 MHz). The proposed antenna is constructed of a main central patch and a ring surrounding it, both with truncated corners to achieve the desired circular polarisation characteristics. The two patches are connected to each other using four long and thin microstrip transmission lines. The design, simulation and measured results are presented. The effects of varying key antenna physical parameters were carefully examined and discussed in detail to characterise their effects on operational bandwidth.

Phase delay characteristics of the complementary triangular split ring resonator (CTSRR) loaded transmission line with capacitive stubs are presented. The phase responses of a reference microstrip transmission line and a transmission line with capacitive stubs, loaded with the CTSRR on the ground plane, are compared. The practical results show that the CTSRR loaded transmission line provides four times more phase delay when compared with a reference transmission line, and thus the proposed configuration provides a 76% transmission line length reduction.

Dielectric resonator antennas (DRAs) excited by tall microstrip transmission lines (TMLs) are investigated. Two different TML–DRA structures are proposed and the impact of TML parameters on the antenna performance is studied when low-loss and lossy substrates are used. To validate the effectiveness of this approach, a set of prototype antennas was fabricated, measured and compared with simulation results. A good agreement is obtained. It is found that by adjusting TML parameters, excellent impedance matching and coupling to low-permittivity DRAs are achieved even on high-permittivity substrates. The impedance bandwidth of a single-mode simple-shape rectangular DRA with ɛrd = 9 can be as high as 25%. The radiation efficiency of the antenna on extremely lossy substrates is significantly improved and based on the measured results over 80% efficiency with a gain ranging from 4.2 to 5.5 dBi along the impedance bandwidth can be expected. Since TML is a low-loss transmission line, the DRA is a low-loss radiator and low-permittivity DRAs can be well matched by TML, the TML–DRA forms an excellent wideband antenna system with high radiation efficiency.

When an electromagnetic (EM) wave propagates in a medium whose properties are varied abruptly in time, the wave experiences refractions and reflections known as time-refractions and time-reflections, both manifesting spectral translation as a consequence of the abrupt change of the medium and the conservation of momentum. However, while the time-refracted wave continues to propagate with the same wave-vector, the time-reflected wave propagates backward with a conjugate phase despite the lack of any spatial interface. Importantly, while time-refraction is always significant, observing time-reflection poses a major challenge – because it requires a large change in the medium occurring within a single cycle of the EM wave. For that reason, time-reflection of EM waves was observed only recently. Here, we present the observation of microwave pulses at the highest frequency ever observed (0.59 GHz), and the experimental evidence of the phase-conjugation nature of time-reflected waves. Our experiments are carried out in a periodically-loaded microstrip line with optically-controlled picosecond-switchable photodiodes. Our system paves the way to the experimental realization of Photonic Time-Crystals at GHz frequencies. Time-reflected waves are a critical feature of time-crystals, yet their properties are historically difficult to measure. Here, the authors experimentally demonstrate time-reflected electromagnetic waves including direct evidence of their phase conjugate nature.

Coincidence detection of single photons is crucial in numerous quantum technologies and usually requires multiple time-resolved single-photon detectors. However, the electronic readout becomes a major challenge when the measurement basis scales to large numbers of spatial modes. Here, we address this problem by introducing a two-terminal coincidence detector that enables scalable readout of an array of detector segments based on superconducting nanowire microstrip transmission line. Exploiting timing logic, we demonstrate a sixteen-element detector that resolves all 136 possible single-photon and two-photon coincidence events. We further explore the pulse shapes of the detector output and resolve up to four-photon events in a four-element device, giving the detector photon-number-resolving capability. This new detector architecture and operating scheme will be particularly useful for multi-photon coincidence detection in large-scale photonic integrated circuits.