Study and applications of retrodirective and self-adaptive electromagnetic wave controls to a Mars probe Quarterly report, 1 Oct. - 31 Dec. 1965

Design feasibility and applications of adaptive antenna circuits for deep space communication - antenna concepts, environmental effects, and phase lock loops and adaptive circuitr

Study and applications of retrodirective and self adaptive electromagnetic-wave phase controls to a Mars probe

Computer analyses of retrodirective, and self adaptive antenna phase control techniques for Mars prob

Establishing Multi-User MIMO Communications Automatically Using Retrodirective Arrays

Communications in the mmWave and THz bands will be a key technological pillar for next-generation wireless networks. However, the increase in frequency results in an increase in path loss, which must be compensated for by using large antenna arrays. This introduces challenging issues due to power consumption, signalling overhead for channel estimation, hardware complexity, and slow beamforming and beam alignment schemes, which are in contrast with the requirements of next-generation wireless networks. In this paper, we propose the adoption of a retro-directive antenna array (RAA) at the user equipment (UE) side, where the signal sent by the base station (BS) is reflected towards the source after being conjugated and phase-modulated according to the UE data. By making use of modified Power Methods for the computation of the eigenvectors of the resulting round-trip channel, it is shown that, in single and multi-user multiple-input multiple-output (MIMO) scenarios, ultra-low complexity UEs can establish parallel communication links automatically with the BS in a very short time. This is done in a blind way, also by tracking fast channel variations while communicating, without the need for ADC chains at the UE as well as without explicit channel estimation and time-consuming beamforming and beam alignment schemes

Navigation/traffic control satellite mission study. Volume 4 - Critical technology, growth and economic summaries Final report

Navigation and traffic control satellite network developmen

Advanced deep space communication systems study Final report

Deep space communication system requirements for period 1970 to 198

The practical implementation of a retrodirective cross-eye jammer by using software defined radio (SDR)

Dissertation (MEng (Electronic Engineering))--University of Pretoria, 2022.Radar-guided missiles have the potential to cause extreme damage to vital military assets. Although traditional deception techniques can deceive radars in range and Doppler shift, only a few methods can deceive them in angle. Cross-eye jamming was identified as a possible countermeasure against angular radar threats. This electronic attack (EA) method works by artificially creating the worst case of glint in angular radars. Numerous analyses of cross-eye jamming exist in the literature. The earlier analyses were derivative glint analyses that made two incorrect assumptions. The first was to use linear fits to the monopulse antenna patterns, which is only valid when the target platform is on broadside of the radar. The second was to assume that the target platform is an infinite distance from the radar, which is not possible. The analyses also did not consider retrodirectivity. It was only during a later cross-eye jamming analysis that the limitations were identified and corrected. The limitations in the analysis could have been identified much sooner if practical measurements were made. The extended cross-eye jamming analysis made fewer assumptions and was proven accurate by numerous simulations and some experimental results. However, the only available experiments where the radar rotation was considered did not implement true retrodirectivity but simulated it by combining isolated channel measurements. A need was identified for the development of a truly-retrodirective cross-eye jammer in a laboratory environment to expand the body of knowledge available about cross-eye jamming. The cost-effective jammer would be used to identify any real-world effects or anomalies that could not be predicted by the extended analysis or identified by simulation. This dissertation presents the development of a truly-retrodirective cross-eye jammer by using a software-defined radio (SDR). The development is accompanied by a method of calibrating the cross-eye jammer to obtain the ideal magnitude factor and phase difference between the retrodirective paths by minimising the magnitude of the sum-channel return of a monopulse radar. The developed system was tested in an anechoic environment against a self-implemented phase-comparison monopulse radar. It was shown that significant angular errors could be induced. The angular errors were larger than 10° at broadside of the radar. This equated to a minimum miss-distance of around 1 m at a range of 6 m. It was shown that a cross-eye gain of around ten was obtained, which resulted in the indicated angle of the radar never becoming zero, regardless of the radar rotation. This suggested that tracking radars, such as that used by active homing missiles, would lose lock on the target platform. Further experiments also proved the jammer to be retrodirective, with large angular errors for all rotations of the jammer antennas. All results correlated very well with that predicted by the extended analysis, with only minor deviations between radar rotations of 0° and 5°. After further investigation, it was concluded that the deviations were most likely caused by mutual coupling between the radar antennas and were not caused by a reduction in the performance of the jammer.Electrical, Electronic and Computer EngineeringMEng (Electronic Engineering)Unrestricte

Retrodirective phase-lock loop controlled phased array antenna for a solar power satellite system

This thesis proposes a novel technique using a phase-lock loop (PLL) style phase control loop to achieve retrodirective phased array antenna steering. This novel approach introduces the concept of phase scaling and frequency translation. It releases the retrodirective transmit-receive frequency ratio from integer constraints and avoids steering approximation errors. The concept was developed to achieve automatic and precise beam steering for the solar power satellite (SPS). The testing was performed using a transceiver converting a pair of received 2.9 GHz signals down to 10 MHz, and up converting two 10 MHz signals to 5.8 GHz. Phase scaling and conjugation was performed at the 10 MHz IF using linear XOR phase detectors and a PLL loop to synthesize a 10 MHz signal with conjugate phase. A phase control loop design is presented using PLL design theory achieving a full 2π steering range. The concept of retrodirective beam steering is also presented in detail. Operational theory and techniques of the proposed method are presented. The prototype circuit is built and the fabrication details are presented. Measured performance is presented along with measurement techniques. Pilot phase detectors and PCL achieve good linearity as required. The achieved performance is benchmarked with standards derived from likely performance requirements of the SPS and beam steering of small versus large arrays are considered

Retrodirective phased array antenna for nanosatellites

Thesis (M.S.) University of Alaska Fairbanks, 2019This thesis presents a S-band phased array antenna for CubeSat applications. Existing state-of the-art high gain antenna systems are not well suited to the majority of CubeSats, those that fall within the 1U (10 cm x 10 cm x 10 cm) to 3U (10 cm x 10 cm x 30 cm) size ranges and in Low Earth Orbit (LEO). The system presented in this thesis is designed specifically to meet the needs of those satellites. This system is designed to fit on the 1U face (10 cm x 10 cm) of a CubeSat and requires no deployables. The use of beamforming and retrodirective algorithms reduces the pointing requirements of the antenna, easing the strict requirements that high gain antennas typically force on a CubeSat mission. Additionally, this design minimizes volume and uses low cost Commercial-off-the-Shelf (COTS) parts. This thesis discusses the theoretical background of phased array theory and retrodirective algorithms. Analysis are presented that show the characteristics and advantages of retrodirective phased antenna systems. Preliminary trade studies and design analyses show the feasibility and expected performance of a system utilizing existing COTS parts. The preliminary analysis shows that an antenna system can be achieved with ≥8.5 dBi of gain, 27dB of transmitted signal gain, 20% Power Added Efficiency (PAE) within a 1 W to 2 W power output, and an 80° effective beamwidth. Simulation results show an example antenna array that achieves 8.14 dBi of gain and an 82° effective beamwidth. Testing results on a prototype of the front-end electronics show that with minimal calibration, the beamforming and scanning error can be reduced to 5°. The power consumption and signal gain of the electronics is also verified through testing. The CubeSat Communications Platform, a CubeSat mission funded through the Air Force Research Laboratory is in Phase A design to demonstrate this antenna system, along with other experimental payloads. This thesis includes a discussion of interface control, mission requirements, operations, and a recommended experiment sequence to test and verify the antenna system on orbit.Alaska Space Grant Program, NASA Space Technology Research Fellowship (80NSSC170185

Microwave power transmitting phased array antenna research project

An initial design study and the development results of an S band RF power transmitting phased array antenna experiment system are presented. The array was to be designed, constructed and instrumented to permit wireless power transmission technology evaluation measurements. The planned measurements were to provide data relative to the achievable performance in the state of the art of flexible surface, retrodirective arrays, as a step in technically evaluating the satellite power system concept for importing to earth, via microwave beams, the nearly continuous solar power available in geosynchronous orbit. Details of the microwave power transmitting phased array design, instrumentation approaches, system block diagrams, and measured component and breadboard characteristics achieved are presented