Graphene-based balanced Nonlinear Transmission-Line frequency doubler. - In: IEEE Xplore digital library, ISSN 2473-2001, (2024), S. 265-268
This paper introduces a tunable balanced Nonlinear Transmission-Line (NLTL) frequency doubler topology designed using graphene-based Monolithic Microwave Integrated Circuit (MMIC) technology. The frequency doubler chip, operating at a centre frequency of 1.6 GHz, is presented alongside its validation through a proof-of-concept Printed Circuit Board (PCB). The proposed topology offers significant advantages, including high harmonics suppression and exceptional phase noise performance. We employ two measurement setups to evaluate the PCB's performance, showcasing the practical applicability of the design. The frequency doubler design achieved remarkable performance, featuring a conversion gain of -11 dB with high tunability. The circuit exhibited good fundamental suppression below -25 dB, and third and fourth harmonic suppression lower than -35 dB. Moreover, the circuit showcased low-phase noise with a delta carrier-to-noise ratio (CNR) of 6.33 dB.
https://doi.org/10.23919/GeMiC59120.2024.10485322
Evaluation of near-field to far-field transformation accuracy based on reference radiation models. - In: AMTA 2023 proceedings, (2023), insges. 6 S.
Measuring the radiation behavior of antennas in an anechoic environment with far-field (FF) conditions requires large measurement sites resulting in high costs. To overcome this problem, near-field (NF) measurement techniques and near-field to far-field (NFFF) transformation are used to derive the FF of an antenna under test. Thus, evaluating the accuracy and reliability of the NFFF transformation is highly important. The first step for this evaluation process is creating a valid and accurate reference data library consisting of NF and FF data. NF data is used as input to the NFFF transformation, whereas FF data is used as a reference for comparison to the FF obtained after the transformation. This paper explores analytical studies for different antenna models, namely a pyramidal horn antenna and an open-ended waveguide. Simulations of the models are carried out in a commercial full-wave electromagnetic software, considering the various input parameters influencing the FF results. The NF and FF data from the parameterized simulation model is used to evaluate the NFFF transformation methods. After optimization of the simulation parameters, the required accuracy levels of -30 dB and -40 dB for two different accuracy metrics defined throughout the paper are achieved.
https://doi.org/10.23919/AMTA58553.2023.10293741
Distributed ISAC systems - multisensor radio access and coordination. - In: 2023 20th European Radar Conference, (2023), S. 351-354
Integrated sensing and communication (ISAC) qualifies mobile radio systems for detecting and localizing of passive objects by means of radar sensing. Advanced ISAC networks rely on distributed infrastructure, multisensor uplink and downlink, or meshed sidelink access. In this way, ISAC develops into a MS-MIMO (multisensor multiple input multiple output) network which constitutes a distributed MIMO radar network. Multisensor link coordination and synchronization are becoming crucial. Many multisensor access and signaling techniques find their communication counterpart in multiuser MIMO and cooperative multilink communications (CoMP) and can be adopted from there.
https://doi.org/10.23919/EuRAD58043.2023.10289611
Mutual over-the-air frequency synchronization of continuous wave signals. - In: 2023 20th European Radar Conference, (2023), S. 363-366
Future communication and radar sensing systems will require synchronization methods which are more versatile in terms of the systems involved in the synchronization process. We present an over-the-air frequency synchronization algorithm based on self-synchronization which uses continuous wave signals. In contrast to other approaches, all nodes of the network participate equally, and synchronization can even be achieved in presence of a non-cooperative node. These claims are supported by measurements conducted with continuous wave radars. It will be demonstrated that our algorithm enables synchronization accuracies down to 1.92 ppb and thus could provide sufficient accuracy for velocity measurements on pedestrians.
https://doi.org/10.23919/EuRAD58043.2023.10289292
Intelligent reflective surfaces for multistatic radar networks. - In: 2023 24th International Radar Symposium (IRS), (2023), S. 1-9
Radar networks promise more reliable detection of radar targets compared to monostatic radars, but require a large number of transmitters and receivers. In this paper, the use of intelligent reflective surfaces is proposed to direct the electromagnetic wave emitted from a monostatic radar and reflected at a target back to the radar receiver. To build the structures without electronic phase shifters, beam broadening is used to establish a reliable link to the radar receiver for different target positions. Results of the simulation of a reflect array show that beam broadening can be achieved for an angular range of at least 20˚ using a quadratic phase distribution.
https://doi.org/10.23919/IRS57608.2023.10172477