METHODS AND DEVICES OF MEASURING SIGNALS GENERATION IN WIDE BAND OF CARRIERS

In many radar and EW applications, after some processing, the envelope of the received pulse is calculated and is used for target detection. Most of the time only the effect of thermal noise is considered in such detectors, but in most of the practical applications, before envelope detection, the signal should be down converted from radio frequency (RF) to an intermediate frequency (IF). In this case, the phase noise of the local oscillator will affect the signal, too. Surprisingly, in contrast to thermal noise, the effect of phase noise on the envelope of signal becomes more considerable whenever the IF bandwidth is decreased. So there exists an optimum IF bandwidth for the receiver. In signals with higher bandwidths, thermal noise degrades the signal and in signals with lower bandwidths, the phase noise affects it. In this paper the optimum bandwidth is calculated under some realistic approximations. (4 pages)

Introduction: Beyond the-5G technologies are targeting the available bandwidth (BW) in the D-band and J-band. This promises for very high speed communication and sensing accuracy. Although the advantages of operating beyond 100 GHz from the application point of view, it requires a lot of research and development to design a reliable and power efficient chipsets. In this presentation we will go through the design of wideband 240 GHz transmitter (Tx) and receiver (Rx). Firstly an overview about the link budget analysis will be given, then the design of the local carrier signal generator will be discussed. The wideband Txs and Rxs are to be presented with frequency channelizing concept. At the end the results of the wireless links will be demonstrated. Link Budget Analysis: Operating at sub-THz frequencies approaching the transistor fT put a lot of constraints on the system link budget. The elevated noise figure together with the limited maximum Pout of the transistors lead to solutions which might be limited in BW or power efficiency. Hence the design architecture need to be optimized taking into account the elevated power consumption and heat dissipation. Carrier Generation: Several approaches could be followed to generate the sub-THz carrier frequency. For a power efficient solution the fundamental oscillators promise for a power efficient solution but with limited phase noise performance and tuning range. Such a solution is more common for imaging systems operating at a single frequency. In order to achieve wider tuning ranges for multi-channel scenario or FMCW radar systems, the frequency multiplication chains are common, whereas the multiplication factor depends on the system parameters. Sub-THz Rx: Different approaches were followed to realize a wideband sub-THz Rx. For some technologies the transistors ft does not promise the realization of low noise amplifiers (LNA) with reasonable noise figure, gain and BW. Hence the mixer first approach were followed trying to optimize the noise figure of the down conversion mixer as much as possible. This also enhances the input compression point (IP1dB) of the Rx which is better for monostatic radar applications. On the other hand, if the technology in use allows the development of well performing LNA’s, the LNA first approach was followed to enhance the all over NF of the receiver and ease the implementation of IQ Rxs. In our work an LNA was implemented followed by IQ downconversion mixers and baseband chain as presented in [3]. Sub-THz Tx: The Tx main challenging performance parameter in the sub-THz frequency range is to achieve high output compression point across the required BW with as high efficiency as possible. Increasing the power handling capabilities of the power amplifiers (PA) by increasing the transistors sizes of the output stages, leads to low output impedance and hence higher impedance transformation ratios for the matching structures and eventually narrow band designs. Hence the power combining architectures were proposed as an alternative to increase the output power either by combining on-chip or combining in air. In this work a fully integrated IQ Tx is to be presented with on-chip LO chain and 4-way power combined power amplifier. Baseband Signal Generation and Processing The baseband topology depend on the application. For mobile communication or localization use cases a wideband channels are not available directly from the digital processors, a kind of channel bonding is required either in the digital domain or in the analog domain. As a proof of concept we present here 3-IQ frequency interleaving combiner. Wireless Link Demonstrator Two demonstrators are to be presented. The first demonstrator is transmitting a broadband IQ signal generated from an arbitrary wave generator wirelessly utilizing an IQ 240GHz Tx and Rx. Data rates up to 100 Gbps were demonstrated across a 1m of wireless link. The second demonstrator includes the implementation of 3-channel IQ channelizer to create the complex modulated signal at several intermediate frequencies (IFs) and then upconverted to the 240GHz carrier signal. On the Rx side the de-channelizer convert the down modulated signal to three IQ channels. Data rates up to 8Gbps were demonstrated wirelessly with the channelization with potential of further enhancements for more channels integration. Outlook The future of the sub-THz wireless links for high speed communication and localizations goes towards implementing phased array and MIMO systems. This requires the research community to develop novel architectures to develop large scale arrays with acceptable power consumptions and suitable packaging solution. On the baseband side also the channel bonding solutions are still in an early stage, requiring more work to bond modularly larger number of channels.

This paper presents a dual-mode intermediate frequency (IF) signal processing circuit for pulse compression radar (PCR) and symbol recovery. A half-duplex architecture is proposed to support modulation and demodulation of PCR signals. For data communication, the modulator and the demodulator support up to 3-Gb/s QPSK signal. For range sensing, the proposed IF correlation technique supports 1.5-GHz bandwidth (BW) and 3/5/7-b Barker codes for 10-cm range resolution. The circuit includes a high-linearity switch, a modulator, a reconfigurable demodulator/correlator, and an in-phase and quadrature clock signal generator. This proposed system is fabricated with 90-nm CMOS, and each channel can be configured to operate from 200 Mb/s to 1.5 Gb/s with different Barker codes. The maximum power consumption is 54 mW with 1.5-GHz BW (10 cm) in range sensing mode and 49 mW at a rate of 3 Gb/s in data communication mode.

We consider operational and structural features of a millimeter-wave balanced mixer with a broadband intermediate-frequency (IF) output. In this case, the heterodyne frequency is in the close vicinity of the IF band. The problem is reduced to an increase in isolation in the heterodyne-IF circuit along with the decrease in the mixer conversion loss in the broad IF band. As a result, we realized the mixer design with the following parameters: mixer input band 26-40 GHz, IF output band 0-18 GHz, conversion loss 6-8 dB, and heterodyne-IF isolation is 10-20 dB. The mixer circuit based on a combination of waveguide-slotted, coplanar, and microstrip transmission lines is studied.

We present a photonic approach to realize radio frequency (RF) down-conversion and intermediate frequency (IF) channel switching for satellite communication. Conventionally, photonic RF mixers always suffer from limitations of one operational state and one IF channel. We proposed a photonic repeater that can realize multiple frequency down-conversion states and different IF channel switching. Two separated RF ports and two independent local oscillator ports ensure the repeater can down-convert RF signals in different bands simultaneously. Based on the characteristic that orthogonally polarized optical signals cannot beat with each other, the crosstalk between different channels is alleviated. Since no optical filters are involved, the repeater can process broadband RF signals down-conversion and broadband IF signals channel switching. The proposed photonic repeater features compact structure, broad and different bands of operation, and no physical optical splitting, which is promising for a satellite payload.

Seed germination represents a pivotal step in crop establishment, directly influencing early vigor and yield potential. This study evaluated the effect of a Special Signal Form (SSF) treatment on chickpea (Cicer arietinum) seed germination under controlled laboratory conditions. Two batches of 100 disinfected seeds were prepared: one control and one treated with SSF. Importantly, the seeds used in this study presented low initial germination potential, corresponding to an aged or sub-optimal lot. Seeds were incubated on agar medium at 25 °C and monitored daily for four days. Results showed that SSF stimulation significantly enhanced germination kinetics, with a +26% increase compared to the control, particularly on days 3 and 4. These results suggest that SSF technology can revive low-vigor seeds, accelerating their metabolic activation and improving emergence uniformity. This highlights the potential of SSF as a non-chemical, remote biostimulation technology for restoring viability and boosting early crop performance. The acceleration and homogenisation of germination suggest that SSF may stimulate seed metabolic activation and improve uniformity of stand establishment. Given that seed treatments and priming approaches (e.g., microbial biopriming, nanomaterial coatings) have previously been shown to enhance germination and seedling growth (e.g., Rouphael & Colla, 2020; Zhao et al., 2024) and mitigate abiotic stress (e.g., Cardarelli et al., 2025), the present results support SSF as a promising, non-chemical biostimulant approach for sustainable agriculture. Special Signal Form (SSF) are structured, low-intensity electromagnetic emissions that are being studied for their potential interactions with living systems.Nature of Special Shape Signals (SSF) SSF are low-frequency (<100 Hz) electromagnetic signals structured according to specific sequences (harmonics, pulsed forms, scalar wave vortices). These signals are designed to interact with biological or aqueous environments, potentially modifying: The surface tension of water, The coherence of dipolar domains, Enzymatic activity at interfaces (Pollack, 2013; Smith, 2009). This study explores their effects on chickpea seed germination, focusing on the germination rate index. The hypothesis is that SSF modify the physical properties of the seeds, promoting better germination. An experimental protocol was established to quantify germination rates. This approach opens new perspectives for understanding seed-plant interactions under subtle signal influence.

In this paper, a single polarized absorptive frequency selective surface (AFSS) with ultra-wide transmission band and broad absorption band has been proposed numerically and experimentally. Based on the principle of circuit analog absorber (CAA), the proposed wideband AFSS is realized via replacing the ground plane with a band-stop frequency selective sturcture. The proposed AFSS is finally a hybrid structure composed of a wideband lossy frequency selective surface (FSS) in the top and a 3D band-stop frequency selective structure in the bottom. The wideband lossy FSS with thinner profile in the top is realized by utilizing a low pass capasitive elements to compensate the equivalent load inductance arising from the air space that is less than quarter wavelength installing between FSS and ground plane, and the low pass capactive lossy FSS is synthesized using “Gong”-shaped patterns with lumped resistors. Meanwhile, the unit cell of 3D frequency selective structure consists of two electrical coupling C-shaped patterns is investigated to achieve a wide stop band with high selectivity, which can be equivalent to the ground plane in the absorption band. By cascading the wideband lossy FSS and the 3D band-stop frequency selective structure, a thinner hybrid AFSS is presented with ultra-wide transmission band and broad absorption band. The results obtained from simulation shown that an absorption band with absorptivity above 90% is obtained from 6.6 to 11.6 GHz, and the 1 dB transmisson band is from 1 to 3.5 GHz with minimum insertion loss of 0.21 dB. Moreover, the performance can be guaranteed for TE-polarized oblique incidence up to 30°. Finally, a prototype is fabricated to validate its performance, the measured results shown that the 1 dB transmission band ranges from 1 to 3.5 GHz, and the absorption band is operating from 6.3 to 11 GHz at normal TE-polarized incidence. A good agreement between the experiment and simulation results is achieved, which verifies the effectiveness of the design.

This paper presents a different approach of Intermediate Frequency (IF) amplifier using 0.18 μm MIETEC technology channel length of MOSFET Darlington transistors. In contrast to Bipolar conventional Darlingtonpair, a MOSFET Darlington configuration is employed to reduce supply voltage (VDD) and DC consumption power (Pc). The frequency response parameters of the proposed design such as bandwidth, gain bandwidth product, input/output noises and noise figure (NF) are improved in proposed (IF) amplifier. Moreover, a dual-input and dual-output (DIDO) IF amplifier constructed from two symmetrical single input and single output (SISO) (IF) amplifier is proposed too. The idea is to achieve improved bandwidth, and flat response, because these parameters are very important in high frequency applications. Simulation results that obtained by P-SPICE program are 1.2 GHz Bandwidth (BW), 3.4 GHz (gain bandwidth product), 0.5 mW DC consumption power (Pc) and the low total output noise is 12 nV with 1.2 V single supply voltage.

Quad channel wideband frequency conversion unit converts wide band RF (Radio frequency) input band to Intermediate frequency (IF) band, with built in Local Oscillator (LO) signals. Down conversion architecture proposed here is for Electronic Warfare (EW) applications. Input RF signal is first separated into three bands based on frequency as Sub RF Band 1 (L Band), Sub RF Band 2 (C Band) & Sub RF Band 3 (S Band). Wideband RF diplexer separates sub RF Band 2 & 3. Sub RF Band 1 is processed directly. Sub RF Band 2 & 3 are down converted to IF Bands. Four such identical channels of processing/ down conversion are implemented. LO signals in C band are built in and are generated using Phase Locked loops (PLL). Super heterodyne down conversion architecture is employed here. Sub RF bands processing, LO generation & distribution are all implemented on composite dielectric multilayer printed circuit boards. The proposed architecture provides instantaneous interleaved IF processing bandwidth (BW) of 4000 MHz, Typical Gain of 7 dB, Typical Noise Figure (NF) of 12 dB, Harmonics & Intermodulation products performance of -50 dBc, LO & Image rejection of -50 dBc.

Retrieval of ocean colour information from a space borne Multi‐spectral Camera (MSC) on KOMPSAT‐2 is investigated to study and characterize small‐scale biogeophysical features that are very rich and dynamic in nature in the coastal oceans rather than the interior. Prior to the derivation of this information from space‐borne ocean colour observations, the path radiance largely from the atmospheric path and air–sea interface should be removed from the total signal recorded at the top of the atmosphere (TTOA ). In this study, the ‘path extraction’ method is introduced for the atmospheric correction of ocean colour images. The potential use of path extraction was demonstrated on Landsat TM and SeaWiFS images of highly turbid coastal waters of Korea. The path‐extracted water‐leaving radiance was then compared with the water‐leaving radiance spectra derived from the standard SeaWiFS atmospheric correction algorithm. It was noticed that the path‐extracted water‐leaving radiance resembled in situ spectra while the same was found highly degraded throughout the visible wavebands by adopting the standard SeaWiFS atmospheric correction algorithm. Algorithms for the retrieval of ocean colour information are explored from remotely sensed reflectance (Rrs ) in the visible wavelength bands of a Multi‐spectral Camera. A large set of remote sensing reflectances are generated by random number functions using an Rrs model, which relates bb /(a+bb ) to Rrs as functions of inherent optical properties, such as absorption and backscattering coefficients of six water components including water, phytoplankton (chl), dissolved organic matter (DOM), suspended sediment (SS) concentration, heterotropic organisms (he) and an unknown component, possibly represented by bubbles or other particulates unrelated to the first five components. Since the Kompsat‐2 MSC and Landsat‐5 TM bands are spectrally similar, these Rrs values are then modelled to the equivalent remote sensing reflectances at MSC and Landsat TM bands using a spectral band model. The empirical relationships between the spectral ratios of modelled Rrs (e.g. Rrs (MSC band1)/Rrs (MSC band2) and Rrs (MSC band1‐centre)/Rrs (MSC band2‐centre)) and chlorophyll concentrations are established in order to derive ⟨chl⟩ algorithms for both Landsat TM and MSC bands. Similarly, ⟨SS⟩ algorithms are obtained by relating a single band reflectance (e.g. Rrs (MSC band2) and Rrs (MSC Band2‐centre)) to the suspended sediment concentrations. Finally, a comparative analysis is made between the Landsat TM and MSC bands as well as narrow (centre‐wavelength) and broad band (full bandwidth) width of algorithms. From this study, it was observed that the Rrs spectra of three MSC spectral bands are found to be slightly superior to the Landsat TM bands in terms of spectral sensitivity to varying constituent concentrations. A small discrepancy between the reflectance ratios of broad and narrow bands was noticed in MSC and Landsat TM. The coefficient of determination (R 2) for log‐transformed data [⟨chl⟩ N = 500] was interestingly found to be R 2 = 0.90 for both Landsat TM and MSC. Similarly, the R 2 value for log‐transformed data [⟨SS⟩ N = 500] was 0.93 and 0.92 for Landsat TM and MSC, respectively. The modelled Rrs spectra were in good agreement with our in situ spectra obtained from the southern coastal Sea of Korea during 1998 and 1999. The algorithms presented are expected to explore the fine details of the complex coastal oceanic features from the ocean colour images of Multi‐spectral Camera and Landsat TM.

A class of time-dithered ultrawideband (UWB) systems is modeled and simulated from an analytic description of the system. These simulated time waveforms and Fourier spectra results are analyzed to show the effect of a receiver's intermediate frequency (IF) bandwidth (BW) on peak and average power. The peak and average power curves provide the basis for establishing a normalized bandwidth correction factor (BWCF) curve and equation. The BWCF is used to estimate peak power over a range of BWs from average power measurements made in a 1 MHz BW. Peak and average power are computed and compared over BWs from 0.3 MHz to 100 MHz for both pre and post detection. The 50% dithered case is also compared to a non-dithered periodic system which exhibited constant power curves as a function of IF BW below the pulse repetition rate (PRR) of 10 MHz. All of the curves increased linearly in power with, BW on log-log plots. Peak power increased more rap idly than average power above the PRR for all cases.

Aiming at the problems of weak robustness of single feature and limited recognition range in modulation recognition, this paper proposes a modulation recognition algorithm based on cascaded feature fusion and multi‐classifier combination, in which time‐frequency map and instantaneous amplitude spectral density features are extracted from low intermediate frequency (IF) signal, constellation map and high‐order cumulant features are extracted from zero IF signal, and a three‐level recognition algorithm is designed through the decision fusion of decision tree, convolutional neural network, and support vector machine. In order to verify the performance of the algorithm, a modulation recognition system is designed and built based on USRP2974. The low IF and zero IF modulation signals are received through two channels, and the RF signals are received and processed in real time with the help of the built‐in CPU of the receiver. The recognition of 13 kinds of analog modulation and digital modulation signals is realized. Under the condition of wireless reception, the recognition rate of this system is more than 93% at 5 to 10 dB.

In this paper the first thirty-two axisymmetric modes for steady-periodic waves in viscous compressible liquids contained in rigid, impermeable, circular tubes are calculated. These results end long speculation over the effects of viscosity on guided acoustic waves. Sixteen of the modes belong to a family of rotation-dominated modes whose existence was previously unknown. The thirty-two modes were computed for a wide range of frequencies, viscosities and wave-lengths.The modes were found through the use of the method of eigenvalleys, which also led to the discovery of backward-propagating waves, an exact analytical expression for the zeroth rotational mode eigenvalue, definitive boundaries between low and intermediate frequencies and between intermediate and high frequencies, and a new type of boundary layer, called a dilatational boundary layer.

This paper presents a 3.5-to-6.2-GHz high-linearity mixer-first superheterodyne receiver chipset that utilizes gigahertz intermediate-frequency (IF) acoustic filters and a Weaver-like mixed-domain recombination architecture. The proposed mixed-domain recombination architecture enables a high IF (2.6 GHz) with a wide (170 MHz) instantaneous bandwidth (BW) and reduces the number of IF lossy passive components. Leveraging inherent quadrature down-conversion in the IF receiver, we adopt complex baseband signal processing to compensate in-phase and quadrature mismatch. Also, we identify that the IF integrated transformer loss is asymmetrical with respect to primary and secondary winding quality factors, and hence utilize stacked transformers for low loss and compact size. The chipset is fabricated using a 65-nm CMOS process and demonstrates, in measurement, an out-of-band IIP3 of +27 dBm at <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathrm{1}\times \text{BW}$</tex> offset with a 9.7-dB NF at 3.5-GHz RF.

Successful management of the radio spectrum requires, as a first step, detailed information about spectrum occupancy. In this work, we present an end-to-end deep learning (DL) based framework to obtain information from wide spectrum bands through signal detection, localization, and modulation classification. By visually representing the radio signals in spectrograms, we formulate the wideband detection problem as an object detection task from the computer vision field. To this end, the proposed framework consists of two cascaded modules: an object detection network repurposed to detect and classify distinctive signals in wideband spectrograms, and a convolutional neural network (CNN) designed to extend the classification capabilities to support a wide range of analog and digital modulation schemes. To evaluate our framework, we use a public wideband recognition dataset, which we carefully analyze and curate through a series of preprocessing techniques. To tackle the challenges of insufficient training data and class imbalance observed in the dataset, we suggest a training strategy that includes data mixing and transfer learning. Our experimental results on a general test set demonstrate that the proposed approach can detect and classify a variety of narrowband signals with simultaneously high precision (77.1%), recall (81.8%), and localization accuracy, as indicated by an average Intersection over Union (IoU) of 86%.