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To ensure the safety and security of airport runway operations, the automatic foreign object debris (FOD) detection system has been developed recently. We have been working on a FOD detection system based on a distributed-type millimeter-wave radar sensor operating in the 90 GHz band. In this paper, the sensitivity improvement of the radar, which is mainly achieved by using signal processing, is discussed based on experimental results at the actual airport runway. The reflection power of the typical 9 FODs is measured at various angles. The detection probabilities are then calculated using the measured results. At 307 m, the detection probabilities of 7 types of the FOD, including small FOD such as a 3 cm piece of asphalt and a 2 cm length M8 bolt, are 100%. These findings support the radar sensor’s improved detection performance.

Detection probabilities of a 96 GHz millimeter-wave airport foreign object debris (FOD) detection radar system are estimated based on both airport measurement results and radar cross section (RCS) measurement results. Firstly, the reflection power and signal-to-noise ratio of a 1-inch height and 1-inch diameter metallic cylinder on an airport runway are measured using an experimental FOD detection system. Secondly, RCS values of typical runway FOD are measured in an anechoic chamber. Then, the measured RCS values of the typical FOD are compared with detection threshold values obtained with the metallic cylinder. Finally, detection probabilities of typical FOD samples are obtained at 250 m, 300 m and 500 m.

The reflection power from 12.6 mm diameter high-voltage power lines located between two islands was evaluated using a 76 GHz helicopter forward-looking low transmitting power millimeter-wave radar. Firstly, the specifications of the radar system are discussed. Then, reflection power measurements are carried out with a distance of 370 m between the radar and the high-voltage power lines. Both the specular reflection and Bragg scattering are measured with different incident angles. In addition, it is confirmed that a maximum 30 dB signal-to-noise ratio is obtained.

The Foreign Object and Debris (FOD) must be removed to keep the safe operation of airports. Some of FOD Detection Systems (FODDS) are in service. This paper describes the development of international standards for FODDS.

In order to accelerate the speed of security inspections at airports, authors propose a new hybrid radar system which has two functions to create passive radio images from thermal noise picture and active radio images from radar picture by the same hardware. In this paper, we conducted a basic study on passive radio imaging technology for receiving weak incoming radio waves. This paper also describes a radio interferometer using two receivers, and reports on test results of incoming noise buried in receiver noise. In addition, we describe the verification results of an algorithm that generates a two-dimensional image by synthetic aperture processing based on the results obtained by moving one receiver and simulating a two-dimensional receiver array.

We are developing Foreign Objects and Debris (FOD) detection system for runways. We introduce the millimeter wave radar system with high rage resolution obtained by the combination of 90 GHz millimeter wave and Radio over Fiber (RoF) technologies. This paper describes the development of multi-static millimeter wave radar which has plural radio heads connected by RoF to create the real-time radar image of 2-D map. We found the architecture of multi-static millimeter wave radar can estimate the position of the FOD using data which are obtained successfully.

An airport runway foreign object debris (FOD) detection system enables automatic detection of small objects which may cause damage to aircraft. We have been developing a FOD detection system based on an optically-connected 96 GHz distributed-type millimeter-wave radar. In this paper, the reflection angle dependency of 11 typical pieces of FOD on an airport runway are measured using a prototype millimeter-wave radar system located in the actual airport. The measured FOD includes a metallic cylinder, a plastic ball, a wrench, a bolt, and a metallic strip. Then, the detection probabilities of the FOD are evaluated based on the measurement results. The detection probabilities of all pieces of FOD are 100% at a distance of 250 m. In addition, the detection probability will be 100% at 500 m with a 10 dB improvement in radar sensitivity.

Wireless Avionics Intra-Communication (WAIC) devices operate between 4,200 MHz and 4,400 MHz. This is the same frequency band as aircraft radio altimeters. In this paper, to investigate the coexistence conditions, the radio altimeter interference path loss (IPL) due to an assumed WAIC device is investigated. Firstly, an overview of the Beechcraft B300, a medium sized turboprop aircraft, is given. Then, the radio altimeter IPL measurement set-up is discussed. The measurement set-up and procedures are based on the RTCA DO-307A procedure. Finally, the IPL values are calculated using the measurement results. The minimum IPL value with the transmitting antenna inside of the cabin is 72.8 dB. This is not significantly small compared with that of the Airbus A321 (74.4 dB). In addition, the median IPL value with the transmitting antenna inside of the cabin is 90.9 dB.

The equivalent isotopically radiated power (EIRP) of a wireless avionics intra-communication (WAIC) system is limited to 6 dBm/MHz at the geometrical center of the aircraft, to avoid interference with aircraft radio altimeters, which are operated at the same frequency band between 4,200–4,400 MHz. In this paper, the height and angle characteristics of the point source EIRP of a WAIC system are analyzed based on the large scale FDTD analysis. Firstly, the strength of the electric field (E-field) around the three-dimensional model of Airbus A320-200 is analyzed. Then, the point source EIRP is calculated based on the analyzed E-field strength. Finally, the height and angle characteristics are analyzed to estimate the electromagnetic field characteristics of the aircraft.

To detect small foreign-object debris (FOD) on airport runways, an FOD detection system based on optically connected 96-GHz distributed-type millimeter-wave radar has been developed. In this paper, long-distance coherent signal transmission and reception by this Radio-over-Fiber (RoF)-based radar system are discussed. Firstly, a coherent signal network based on optical wavelength-division multiplexers is proposed. The radar transmission and receiving signals are transferred by millimeter-wave RoF and 10 gigabit Ethernet, respectively. The signal integration performances are then evaluated using the radar test-bed. The results show a noise floor reduction effect approaching the theoretical value.

Foreign object debris (FOD) on airport runways must be removed immediately. To detect small debris, we proposed and developed an optically-connected distributed-type 96 GHz millimeter-wave radar system based on radio-over-fiber (RoF) technology and an optical fiber network. The proposed distributed-type radar system offers both improved FOD detection characteristics and cost performance. This paper details the design and field feasibility evaluation of the 96 GHz frequency-modulated continuous wave radar system that uses RoF and an optical frequency multiplier. Firstly, the problem of long distance RoF transmission, which limits the practical use of the RoF networked radar system in the airport environment, is discussed. Secondly, the concept and architecture of the millimeter-wave radar system are discussed and demonstrated focusing on its use in actual airports. Then, the results of a field experiment are shown to confirm the feasibility of the radar system. Finally, the effectiveness of the high-speed signal processing and generation circuits inside the central unit is evaluated at an actual airport based on the results of non-coherent and coherent signal integration.

We are investigating the millimeter wave radar system to cover the vast space with high range resolution. These challenges are owing to the combination of 90GHz millimeter wave and Radio over Fiber (RoF) technologies. In this paper, we introduce millimeter wave radar technology networked using RoF. In addition, we introduce 2-D radar image generation from three 1-D distance measurement results. And we show the measurement results conducted in the laboratory.

The fundamental receiving performance of an optically-connected 96 GHz millimeter-wave radar depends on the phase noise of the transmission signal is investigated. We experimentally evaluate this performance by generating a 96 GHz frequency-modulated continuous wave (FMCW) signal by multiplying a 4 GHz signal. The phase noise degrades by about 28 dB due to the 24-fold multiplication. Next, the performance of the radar system with the two FMCW signal sources is measured in an anechoic chamber. The results show that the effectiveness of the low-phase-noise signal generator.

System Wide Information Management (SWIM) concept is now considered in the International Civil Aviation Organization (ICAO) for an efficient and secure information sharing among air traffic controllers, pilots, and airport operators. However, it is difficult for current air-ground communication systems to satisfy these requirements. To achieve rich information exchange between the aircraft and the Air Traffic Management (ATM) service providers at the airport surface and en-route areas, we have developed a new Aeronautical Mobile Airport Communications System (AeroMACS). In this paper, we present the practical experiments and technical analysis for collaborative information exchange between the mobile vehicle and ground SWIM applications by using AeroMACS. It is effective to share various information over AeroMACS, since it has higher capacity and is securer than traditional aeronautical communication systems. As preliminary experiments for flight test, we carried out filed taxing experiments using test vehicle. The results show the effectiveness of AeroMACS for air-ground SWIM integration.

International audience; An obstacle detection forward-looking 76 GHz millimeter-wave system for civil helicopters is developed and evaluated by flight experiments. The purpose of the radar system is to detect high-voltage power lines. Firstly, characteristics of the developed 76 GHz millimeter-wave radar system, which has a transmitting power of 10 dBm, a circular polarized antenna and real-time signal processing, are discussed. Then, the results of ground experiments to obtain a static reflection from the target high-voltage power lines reveal a signal-to-noise ratio of approximately 20 dB at a distance around 1,430 m. Finally, flight experiments are conducted using the developed radar and an obstacle mapping system. The measured maximum detection distance of the power pylons and the high-voltage power lines is approximately 1,970 m and 1,570 m, respectively.

Herein, millimeter-wave radar systems for helicopter all-around obstacle detection are proposed. These systems detect and avoid obstacles to ensure flight safety. First, the configuration of a 24 GHz quasi-millimeter-wave radar module is presented. Second, the development of an all-around obstacle detection system with such radar modules is described. Then, the experiments using the all-around obstacle detection system and the multicopter are conducted to examine the fundamental performance of the developed system.

Radio altimeters and wireless avionics intra-communication (WAIC) systems are both operated at the frequency band 4,200 MHz-4,400 MHz. Hence, a detailed analysis is required for spectrum sharing in the same band. Firstly, a large-scale finite-difference time-domain analysis is performed to obtain the detailed characteristics of the electromagnetic field (EMF) around the three-dimensional Airbus A320 aircraft model, which assumes that a WAIC device is located inside the cabin. Then, the 4-GHz EMF propagation characteristics are evaluated based on the analyzed results. Finally, the methodology of the interference analysis is discussed based on the obtained EMF characteristics.

System wide information management (SWIM) is a recent concept for providing efficient and safe information sharing in civil aviation. The goal in implementing SWIM is to achieve seamless air traffic management (ATM) services worldwide through the efficient integration of the current ATM systems. In this paper, we consider the wireless media to access SWIM. In the International Civil Aviation Organization (ICAO), the aeronautical mobile airport communications system (AeroMACS) is standardized for the next generation airport surface communication system. It is effective to share various types of information among air traffic controllers, pilots, and airport operators, not only on airport surface, but also in taking off and landing by AeroMACS. However, AeroMACS is intended to be used at speeds of 120km/h or below. In this paper, we study the possibility of using AeroMACS while an aircraft is moving at over 120km/h, as would occur in takeoff and landing situations. We conducted flight tests using an AeroMACS standard-compliant prototype system and an experimental aircraft. In the experiments, we obtained a received signal strength indicator (RSSI) to investigate 5GHz ground-to-air propagation. The results revealed that an onboard antenna configuration involving vertical placement at the top and bottom of the aircraft body is effective in achieving multiple input multiple output (MIMO) operation. Additional throughputs measurements showed that it was possible for AeroMACS to access SWIM both in takeoff and landing situations at an aircraft speed of 200km/h.

A mutual-interference mitigation methodology for an optically connected millimeter-wave radar system with several antenna units is proposed based on a common transmission signal and is evaluated in an actual airport. First, the fundamental structure of the mutual-interference mitigation method employing an additional optical fiber for a distance of 10 km as the delay line is discussed. Interference mitigation experiments are then conducted using two antenna units in Sendai Airport. Finally, by plotting a typical one-dimensional beat spectrum with the additional optical delay line, it is confirmed that the interference signal is removed from the beat spectrum.

The effects of electromagnetic lossy materials such as humans, on the electromagnetic field (EMF) characteristics of an aircraft are evaluated using finite-difference time-domain analyses and experiments conducted in a reverberation chamber. This study aims to confirm the EMF reduction effect, through measurements. The results of a large-scale finite-difference time-domain analysis conducted on a model of the B777-200 aircraft with occupants show a reduction in the electric field strength inside the cabin. The EMF loss due to a human phantom is measured quantitatively using a reverberation chamber, between 500 MHz and 6 GHz. The measured quality factor is found to be reduced by 55% when using a full-sized human phantom, which is lower than of the value measured at 2.1 GHz, without using a phantom.

International audience; To improve the detection conditions of the high-voltage power lines using the 76 GHz low-transmitting power helicopter collision avoidance forward looking millimeter-wave radar, the characteristics of the circular polarization is experimentally investigated. Firstly, the specifications and the operating parameters of developed circular polarized 76 GHz is discussed. Then, the radar receiving module with the W-band low noise amplifier and the low loss waveguide to microstrip line transitions enables 12 dB receiving noise figure. Finally, the ground power line detection test is carried out to compare the circular polarization and vertical polarization, which are commonly used to detect the power lines. The results confirm the almost 10 dB increase of the reflection signal of the power lines.

To examine the microwave electromagnetic field (EMF) characteristics inside carbon fiber reinforced plastic (CFRP) structures, the quality factors (Q-factors) of reverberation chambers constructed of either CFRP or aluminum are evaluated and compared. In the CFRP structure, the four sidewalls and ceiling, which are originally made of aluminum, are replaced by CFRP panels, and then the uniformity of the field is evaluated. The standard deviation of the measured maximum electric field strength inside the chamber is less than 1.5 dB between 500 MHz and 6 GHz. The unloaded Q-factor of the CFRP chamber is almost identical to that of the all-aluminum structure below 2.5 GHz; however, it decreased by about 50 % between 2.5 GHz and 6 GHz compared to that of the all-aluminum structure. No significant difference is found in the loaded Q-factors of both structures.

Detection of small foreign object debris (FOD) on airport runways is important to prevent accidents. In this study, an FOD detection system that utilizes optically-connected 96 GHz millimeter-wave radar has been developed. This detection system uses Radio-over-Fiber signal transmission between a signal source and several radar antenna units. Further, field evaluations of the developed radar system are carried out at the Tokyo Narita International Airport. The results confirm that the proposed system is capable of detecting objects surrounding the radar antenna. In addition, a 1 inch × 1 inch (diameter × height) metal cylinder is detected with approximately 20 dB signal-to-noise ratio at 450 m.

Analog wireless link on the fiber is the key technology to deliver the millimeter wave signal to the remote antenna units. Authors are developing a Foreign Objects and Debris (FOD) detection system based on millimeter wave radar connected by Radio over Fiber for runway surveillance in the airport. This radar consists a central station and several remote antenna units to cover the vast area of the runway. The architecture of the system and result of the preliminary test in Narita International Airport are presented.

Electromagnetic compatibly (EMC) is required to be investigated for newly introduced on-board Wireless Avionics Intra-Communication (WAIC) systems. In this paper, the feasibility of the detailed electromagnetic field (EMF) estimation method for the Airbus A320 class passenger aircraft at 4 GHz band is discussed. Firstly, the three-dimensional analysis model based on Airbus A320-200 aircraft is developed for the EMF estimation using the large-scale finite-difference time-domain (FDTD) method. Then, the material constants and the FDTD analysis parameters are discussed. Finally, the analyzed EMF characteristics confirm the effectiveness of the EMC investigation at WAIC band using the numerical analysis.

Recently, much attention has been paid to unmanned aircraft systems (UAS), especially for civilian purposes such as disaster prevention and transportation. This paper considers big long-flight-type UASs remotely piloted from ground station by radio communication link, since these types of UASs require higher reliability. The purpose of this paper is to consider a communication system which transmits real-time video of the surroundings of aircraft from unmanned aircraft to the ground pilot. In this paper, the aeronautical mobile airport communications system (AeroMACS) is considered as a command and non-payload communications (CNPC) link between unmanned aircraft and ground pilot. Flight tests using the experimental aircraft and AeroMACS prototype system are conducted to obtain the air-to-ground propagation profile. In addition, the placements of airborne antennas are considered, because the positional relationship between airborne antenna and ground fixed antenna is not constant during the flight. The results of flight tests show the effectiveness of our system, and the received signal strength indicator (RSSI) obtained by flight tests has the same tendency as the free space propagation model. Finally, the results of flight tests show that a vertical placement on top and bottom of aircraft body is effective for the multiple inputs and multiple outputs (MIMO) antenna configuration of UAS.

We have been developing a Radio-over-Fiber (RoF) connected wideband 96 GHz millimeter-wave radar system to detect small debris on the airport surface such as on runways. As the debris on the runway may cause damage to aircraft, they are required to be removed immediately. This paper discusses the detection characteristic evaluations of the developed 8 GHz frequency-modulated signal bandwidth 96 GHz radar system at an actual airport. The millimeter-wave radar transmission signals are transmitted by the RoF signal. In addition, the −20 dBsm metallic cylinder, which is located on the runway, is measured to investigate the detection characteristics. Then, the effects of the phase noise characteristics of the frequency-modulated continuous wave signal are investigated based on the measurement results.