Conventional terrestrial Very High Frequency (VHF) voice communication systems form the backbone of air ground communications for civil aviation; however, their reliance on line-of-sight propagation fundamentally limits coverage over oceans, polar regions, and other remote areas. These limitations introduce communication gaps that constrain air traffic management efficiency and reduce operational safety margins. Space-based VHF voice communication has recently emerged as a promising complement to ground-based infrastructure, offering seamless, wide-area coverage while maintaining compatibility with existing airborne VHF radios. Unfortunately, routing the VHF communications through space presents some unique technical challenges, such as the scintillation effects of ionosphere on the audio quality of VHF voice signals, and the Doppler offset effects due to the motion of satellite on the demodulation of VHF communication signals and the coexistence with the ground VHF stations. This paper presents a comprehensive design, implementation, and experimental evaluation of a space-based VHF voice communication system for aviation, which include the detailed analysis of ionospheric scintillation and the design considerations for addressing the key challenges on Doppler offset due to satellite motion, carrier offset (for coexistence with terrestrial systems), stringent link budget constraints, deployable satellite VHF antenna, and satellite payload architecture for handing both analog VHF link and digital feeder link. A representative satellite constellation design is also proposed to achieve continuous coverage for Singapore Flight Information Region (FIR). To validate the proposed architecture, a ground demonstrator system is developed, and experimental trial results are presented. These trials demonstrate the feasibility of VHF voice communication over satellite links and confirm the effectiveness of the proposed design. The achieved end-to-end system latency can fully meet the operational requirements for the real-time voice communication in air traffic management.
This document provides a review of the book Advances in Weather Radar, vol. 1.
This paper presents the design, realisation and testing of an inflatable antenna as precursor for an inflatable antenna for radio astronomy. The concept of inflatable antennas is not new, but has gathered renewed attention in the recent years. Most of the historical examples are related to reflector antennas, in which the metallized inflatable structure is used as passive element. The novelty of the research presented in this paper is the use of active antenna elements as part of the inflatable structure while the design is suitable for CubeSat applications. The main advantage of using an inflatable antenna over conventional solutions is the reduced volume during launch and the potential volume when fully expanded. The design consists of a 3x2 series coplanar waveguide inductively fed antenna array operating at 2.4 GHz realized by laser etching 2L-FCCL. It achieves a measured gain of 12.6 dBi per antenna unit cell, with a simulated total gain of 15.6 dBi for the complete antenna. The antenna fits within a box of 10 cm×10 cm×10 cm, with an inflated surface area of $\mathrm{\text{1}~m^{2}}$.
The reconfigurable multi-band notched antenna for UWB, C, X, WLAN andWiMAX band applications are explained in this article. The motivation behind integrating these bands into a single antenna is to address the increasing demand for compact, multi-standard wireless devices capable of mitigating interference from coexisting narrowband systems without the need for external filters.The reconfigurable UWB antenna contains a circular monopole patch and a modified ground plane structure. The ground of the antenna has a centre slit that acts as a simple monopole antenna (SMA) covering the entire UWB band with IBW of 2.97-12 GHz. A T-ring slot is enforced into the patch and feed line after building a simple circular monopole UWB antenna. Multiple PIN diodes are imposed in a particular location in a modified T-ring slot, responsible for switching multiple notches simultaneously while allowing for frequency re-configuration. The surface current distribution of the radiating antenna is changed by the PIN diode biasing (as switch ON/ switch OFF) condition. When all PIN diodes are off, it provides a dual-band notch frequency in WLAN and X-bands. Specifically, interference from WiMAX (3.3-3.8 GHz), WLAN (5-6 GHz), and portions of C- and X-bands can be effectively suppressed. The simulated and measured results of the antenna design are consistent with each other. The measured impedance bandwidth (VSWR ≤ 2) confirms stable UWB operation, while the reconfigurable notch bands show consistent performance across different switching states. The suggested antenna exhibits UWB behaviour and has physical dimensions of 30mm*40mm. The antenna is small and has an excellent E and H-plane radiation pattern, a realised gain of 5 dBi, and a fractional bandwidth of 124 %. It is ideal forWorldwide Interoperability for Microwave Access (WiMAX), Ultra-Wideband (UWB), C-band, Indian National Satellite System (INSAT), Fixed Satellite Service (FSS), Intelligent Transportation System (ITS), Wireless Local Area Network (WLAN), International Telecommunication Union (ITU), and X-band applications.
Conducting actuated control experiments in hypersonic facilities presents unique challenges due to impulsive, short-duration flows and limited core flow size. This paper details the design, control, and testing of a high-bandwidth, small-scale voice coil actuator that addresses these challenges. Analytical and numerical methods are used to investigate key performance relationships, followed by system identification on the experimental hardware to develop a linear state feedback controller. The actuator’s performance is demonstrated in a closed-loop experiment within a short-duration hypersonic wind tunnel. The technology is broadly applicable to subsonic, transonic, and hypersonic facilities, and has the potential to significantly reduce cost while increasing test productivity. This work advances ground-based techniques for fundamental aerodynamics research, flight control testing, and hypersonic vehicle design.
Non-Line-of-Sight (NLOS) perception is essential for preventing potential collisions and finds applications in areas such as autonomous driving, target localization, and human recognition in urban environments. Millimeter-wave (mmWave) radar distinguishes itself by robust NLOS sensing abilities. However, in urban environments, the reflective properties of relay surfaces have become complex. Diverse construction materials, intricate architectural designs, and dynamic environmental variations introduce complexity, violating the conventional assumption of smooth, deterministic geometries and degrading NLOS perception performance. To improve mmWave NLOS sensing under these realistic conditions, we investigate the characteristics of rough relay surfaces and develop a sensing framework to manage multipath interference. Our approach specifically focuses on three specific challenges often overlooked in current research: precise detection under small-scale rough relay surfaces, high-resolution imaging under large-scale relay surfaces, and multipath scattering classification under uncertain surfaces. We establish scattering signal models under different roughness conditions and develop effective NLOS sensing systems based on the distribution characteristics of targets behind different rough surfaces, achieving accurate and reliable sensing.
The opportunistic exploitation of Ku-band downlink signals from Starlink and OneWeb low Earth orbit (LEO) satellites for high-altitude platform station (HAPS) navigation is demonstrated. Named after the Greek mythological figure Icarus, the HAPS consisted of a weather balloon carrying a radio frequency (RF) platform. The HAPS was launched in July 2024 from the Moriarty Municipal Airport, New Mexico, USA, landing near Mountainair, New Mexico, USA. The HAPS traveled southward a 2D distance of 105.3 km, with a 3D distance of 119.2 km. The HAPS reached a peak altitude of 25.3 km (83,000+ ft) above ground. The design of the high altitude RF data collection platform is described. Received LEO signals are modeled and software-defined receivers (SDRs) are implemented to estimate the Doppler frequency shift from downlink signals. Extensive experimental results are presented analyzing Starlink and OneWeb downlink signals over four HAPS segments: (i) stationary at ground-level, (ii) initial takeoff, (iii) cruising altitude, and (iv) peak altitude. SDR tracking results are presented comparing the performance during stationary and in-flight scenarios, and the the received carrier-to-noise density ratio (C/N0) is characterized. An extended Kalman filter (EKF) is designed to fuse Starlink and OneWeb Doppler measurements with altimeter data to estimate the HAPS' states, assuming two dynamical models: velocity random walk and Wiener process acceleration, with the latter model yielding more accurate results, namely a 3D position root mean-squared errors (RMSEs) of (i) 306 m over 4.12 km during initial ascent, (ii) 729 m over 28.24 km while traveling through a presumed jet stream, and (iii) as accurate as 17 m at peak altitude over a 1.38 km trajectory.
Power management is crucial for the success of Martian surface missions. This study presents a comprehensive quantitative assessment of solar irradiance on Mars over a full Martian Year (687 Earth days or 668 Martian sols) under varying atmospheric conditions. Using the COMIMART radiative transfer model and solar data extracted from the Mars Climate Database, we simulate sunlight interaction with atmospheric components, including dust, water ice clouds, and gases, to estimate effective irradiance on sun-tracking solar arrays. Our results indicate that atmospheric losses typically reach up to 25%, with temperature effects on solar cell power conversion efficiency explicitly considered. We provide detailed power generation estimates for the first 180 sols (approximately six months) at two critical landing sites, viz. Elysium Planitia and Oxia Planum, accounting for diurnal irradiance variations. The analysis demonstrates that industry-standard triple junction solar cells maintain efficiency reductions below 5% annually under Martian conditions. Furthermore, we qualitatively and computationally evaluate the impact of dust deposition on solar array performance. This work offers valuable insights for spacecraft designers involved in mission design, solar power system optimisation, and operational planning for Martian exploration.
Commercial aviation accounts for approximately 2.5% of global carbon emissions, with current propulsion systems relying heavily on unsustainable fuels. This study examines the performance of electro-aerodynamic (EAD) thrusters, a potentially zero-emission propulsion system, under varying atmospheric pressures in comparison to conventional propeller systems, aiming to identify the optimal operating conditions of EAD technology within Earth's atmosphere. We used a propeller system as the representative “conventional propulsor” due to its usage in Unmanned Aerial Vehicles (UAVs). An EAD thruster requires a sharp crown-shaped cathode and a smooth ring-shaped anode, which produces “ionic wind” when passing 25 kV of electricity through the electrodes. The thruster is then placed into a vacuum chamber to replicate low-pressure conditions similar to those experienced by aircraft at high altitudes. The air pressure was manipulated using a vacuum pump during our tests. Data analysis revealed that ionic propulsion is generally more efficient than the conventional propeller system, peaking at 1700 mN of thrust at 75 kPa of pressure. The conventional propellers performed their best at 100 kPa, producing 1308 mN of thrust. However, a limitation with EAD thrusters was their tendency to create arcs of electricity when the pressure dropped too low (around 30 kPa), potentially making them unreliable in high-altitude applications. This experiment demonstrates that in environments where pressure exceeds 30 kPa, EAD thrusters offer a greater magnitude of thrust than conventional propeller systems, making them a more efficient and sustainable alternative to current commercial propulsion systems such as those used in UAVs. This work will contribute to the implementation of EAD thrusters on atmospheric aircraft by advancing the understanding of their performance across various atmospheric conditions.
With dynamically simulated false targets generated by airborne miniature simulation platforms becoming increasingly similar to genuine targets, radar discrimination faces mounting challenges. Due to the difficulty of accessing publicly available echo data from such platforms, this paper constructs a simulated dataset. Unlike conventional methods that directly leverage intrinsic features of genuine targets for discrimination, the proposed approach exploits multi-channel statistical discrepancies for identification, without focusing solely on the inherent characteristics of true or false targets, thereby avoiding reliance on real echo data. The method first constructs echo models for both genuine and simulated false targets by leveraging differences in radar cross-section (RCS) under various transmitter–receiver geometries and employing fundamental radar waveforms to build the simulated echo dataset. The resulting simulated false target echoes exhibit high similarity to genuine target echoes. Subsequently, a multi-channel time-frequency correlation statistical feature is proposed. This is achieved by applying Short-Time Fourier Transform (STFT) to echoes from each transmitter–receiver channel to extract time-frequency complex matrices, and then computing the mean of the correlation coefficients among these matrices across all channels. Under multiple observations, genuine and simulated false targets show distinct differences in this feature. Finally, a classifier is designed for training and discrimination. Simulation results demonstrate that, under signal-to-noise ratio (SNR) conditions ranging from –18 dB to 0 dB, the proposed method achieves a discrimination accuracy of at least 83.9% and a Kappa coefficient of at least 0.678 for various types of genuine and simulated targets.
Drone Swarm applications have become increasingly diverse in military reconnaissance, material delivery, and disaster rescue. Task allocation, a key part of swarm execution, has been widely studied. Traditional exact or rule-based methods often struggle to balance solution quality and response time in large or uncertain drone swarm missions. Swarm intelligence (SI) algorithms offer a flexible population-based alternative through distributed search, parallel evaluation, and self-organized adaptation, although their advantages depend on mission structure and reporting conditions. This paper reviews recent literature on SI algorithms for drone swarm task allocation. It summarizes common task allocation models and algorithm families, distills a survey-level five-stage paradigm, and categorizes applications by environmental dynamics and platform homogeneity. The paper also discusses challenges related to dynamic replanning, heterogeneous collaboration, and resource communication constraints, while outlining future research directions for drone swarm task allocation.
TanSat-2 is the successor to TanSat, China's first dedicated carbon monitoring satellite. Compared to TanSat, TanSat-2 features improved designs with enhanced spatial and temporal coverage, a wider range of measurements, and higher measuring accuracy. TanSat-2 achieves near-daily global coverage by using a medium/medium-low earth orbit (M/MLEO) and large swath design, allowing it to monitor most land areas daily. This M/MLEO elliptical orbit intersects with the Van Allen radiation belts, requiring special radiation analysis and protection designs. TanSat-2 also features higher retrieval accu racy and carbon-pollution collaborative monitoring to identify anthropogenic emissions accurately. TanSat-2 carries three key spectrometers: (1) the Ultra-wide-field Carbon Pollution collab orative monitoring Instrument (UCPI), which provides a 2900 km swath and retrieval accuracy for XCO2 (1 ppm), XCH4 (8 ppb), NO2 (1.3×1015 molec cm−2) and SIF (0.3 mW m−2 Sr−1 nm−1); (2) the Hotspot Greenhouse gas Emission Tracker, with a 500-m nadir resolution, designed for tracking carbon emission hotspots; and (3) the Cloud Aerosol Polarization Imager (CAPI). Additionally, TanSat-2 is also equipped with the On board Intelligent Hotspot Extraction and Distribution Instrument (OHEDI), providing high-performance computing capabilities and Beidou short-message capabilities for near-real-time hotspot detection and distribution. The high-precision global observation from TanSat-2 is expected to provide essential data for global assimilation systems to assess global anthropogenic emissions for global carbon stock and other scientific purposes. The near-real time hotspot detection and distribution capability is also expected to be combined with other space-ground observation programs.
Planned missions for human exploration of the Moon, and possibly Mars, have aroused great interest in space networks. Because of long propagation delays and link intermittency, space networks are an example of challenged networks, for which the expected solution is the introduction of the Delay-/Disruption-Tolerant Networking architecture (DTN) with its associated Bundle Protocol. Recently, however, a few researchers have challenged the need for this architecture, and instead suggested extensions to the IP-based Internet architecture for space, based on the addition of some store-and- forward functionalities to the IP protocol and the use of innovative Transport protocols, such as QUIC. The pros and cons of the two different visions have been clearly highlighted by their supporters. Any qualitative reasoning, however, needs to be supported by numbers, thus there is an urgent need for comparative evaluation based on quantitative assessments. The aim of this paper is to provide such a comparison in the scenario of Earth to Moon communications, focusing on transport protocols. After a comprehensive introduction, performance achievable by TCP and QUIC, used end-to-end, is compared with that of the DTN architecture. A significant novelty is that the work presented here is the first side-by-side comparison of end-to-end QUIC vs. DTN with QUICCL/LTP under a common testbed. In the Earth to Moon scenario considered in numerical evaluations, with a terrestrial 10 Mbit/s bottleneck and 2.5 s RTT, the results show that although QUIC outperforms TCP when used end-to-end, DTN architecture can perform better thanks to the isolation of challenges within the hop where they appear, and to the possible use a specialized protocol, LTP, on the space link.
We are pleased to offer the 17th issue of IEEE Aerospace and Engineering Systems tutorials, Tutorial XVII, to members of the IEEE AESS. I am particularly excited about this issue as this is my first issue as the Magazine Tutorials Chair and I want to take this opportunity to express my gratitude to my predecessor, Dr. W. Dale Blair, for his continued guidance and support, as well as for his exceptional service as Magazine Tutorials Chair in the past years.
Although realizing high technology demands rigorous specialization, a historical perspective can present its development as human choice and institutional learning-thereby enabling cross-disciplinary debate on how the technically feasible can be shaped toward what is genuinely desirable. The IEEE HISTory of ELectrotechnology CONference (HISTELCON, 30 September-2 October 2025, Bonn, Germany) showed how historically informed reflection can help rekindle technological passion and position high technology as part of high culture-vital to prosperity and security. Under the theme Knowing the Past for Preparing the Future, opening remarks by the IEEE President and the NATO Chief Scientist framed the link between technology, shared values, and innovation in the service of humanity. Round tables structured plenary sessions on defense and security pathways, the quantum century, and the heritage of intelligence from computing to ethics. Keynotes, topical sessions in parallel tracks, and a strong social program reinforced both technical depth and community building. HISTELCON 2025 also marked a step toward the conference series' worldwide expansion, beginning with Tokyo in 2026.
