Browsing by Author "Kutinlahti, Veli-Pekka"
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Item Amplifier-Antenna Array Optimization for EIRP by Phase Tuning(2022-04-01) Kutinlahti, Veli-Pekka; Lehtovuori, Anu; Viikari, Ville; Department of Electronics and Nanoengineering; Ville Viikari GroupIn this paper, we analyse an antenna array fed with element-specific phase shifters and amplifiers. The elements of the array are mutually coupled and the operation of the amplifiers depend on the load impedance presented by the array. We derive a method for maximizing EIRP in a given direction and demonstrate the concept by simulations with 2x2 array fed with element-specific phase shifters and amplifiers at 2.5 GHz. Compared to the reference case, the optimization provides up to 0.7 dB improvement in EIRP in the −3 dB beam steering range.Item Analyzing and Optimizing the EIRP of a Phase-Tunable Amplifier-Antenna Array(IEEE, 2023-01-06) Kutinlahti, Veli-Pekka; Lehtovuori, Anu; Viikari, Ville; Department of Electronics and Nanoengineering; Ville Viikari GroupWe analyze the performance of an amplifier-antenna array by using separately measured amplifier load-pull data and antenna S-parameters and port-specific radiation patterns. We show that the effective isotropic radiated power (EIRP) of the system can be improved by using phase values which differ from progressive phase shift. Maximum EIRP improvement is 1.1 dB in certain steer directions and over 0.5 dB improvement over a large beamsteering range was measured when compared to using the progressive phase-shift envelope.Item Antenna for Directive Energy Device Against Drones(2019-08-19) Kutinlahti, Veli-Pekka; Holopainen, Jari; Sähkötekniikan korkeakoulu; Viikari, VilleUnmanned aerial vehicles (UAV) have become common in commercial and recreational fields, but also in the hands of criminals. UAVs are used for plural of crimes. Most notably they are used to smuggle contrabands over perimeters, for example to prisons. Presently the industry of neutralizing misused UAVs is growing and testing different methods. Four electromagnetic methods can be distinguished at the moment, which are jamming, spoofing, high-power laser and electromagnetic pulse (EMP). This thesis presents theory on high power microwave (HPM) systems required to design directed EMP system to disable commercial unmanned aerial vehicles and presents a prototype design for high-power circularly polarized directive antenna for the specific purpose. Research of the theory was conducted as a literature review and the design of the antenna was confirmed through electromagnetic simulations on CST Microwave® Studio. Literature review presents basic radiation characteristics of magnetrons, klystrons and backward wave oscillators (BWO), techniques and components for HPM transmission and directive antennas with high power capacity. The different microwave sources are capable of producing microwaves at gigawatt power levels and on frequencies of over 10 GHz. The sole transmission components for HPM are the multitude of different waveguides. The surveyed antennas are the horn antenna, the parabolic antenna, the slotted array waveguide antenna, the helical array antenna and the radial line slotted array (RLSA) antenna. The RLSA was chosen to be designed, because of its low profile. The designed antenna has maximum directivity of 32.8 dB and the system from the magnetron interface to the antenna has a total efficiency of 0.9026=-0.45 dB. The range of the system is estimated to be 130 m with 325 kW input power, within which a commercial UAV is neutralized by the EMP from the antenna.Item Antenna mutual coupling and amplifier effects in transmission(Aalto University, 2024) Kutinlahti, Veli-Pekka; Lehtovuori, Anu, Dr., Aalto University, Department of Electronics and Nanoengineering, Finland; Elektroniikan ja nanotekniikan laitos; Department of Electronics and Nanoengineering; Sähkötekniikan korkeakoulu; School of Electrical Engineering; Viikari, Ville, Prof., Aalto University, Department of Electronics and Nanoengineering, FinlandThe oncoming fifth generation (5G) telecommunication standard utilizes multi-antenna systems to implement multiple-input multiple-output and beam-steering capabilities in most wireless devices, including mobile devices. This shift in transceiver architecture will introduce each antenna element with its own feed control, along with an amplifier and phase shifter chain. The high integration level of these components prohibits the use of traditional ferrite circulators as isolators between the components, introducing the non-ideality of active reflections in the antenna elements to the amplifier outputs. The change in amplifier load impedance causes variation in amplifier output power, linearity, efficiency and can possibly even cause breakage of components in extreme cases. This development is parallel to the fact that 5G will use higher frequencies and wider bandwidth signals, driving the development of innovative design methods to achieve wide-band high-gain antennas with beam-steering capability. The first part of the thesis describes optimizing different aspects of amplifier-antenna systems with mutual-coupling-induced mismatch. First, the equivalent isotropic radiated power (EIRP) of a 2x2 patch antenna array in an amplifier-antenna system is optimized through phase tuning. Phase tuning achieves a maximum 0.7-dB improvement in EIRP within the -3-dB beam steer range at 2.5 GHz, compared to progressive phase shift. Second, the 3rd order intermodulation is minimized with respect to the carrier by adjusting input feed power and phase in a two-tone excited 1x4 amplifier-antenna array, where the beam at each tone is independently steered. Optimization results in a 25-dB improvement in the signal-to-3rd-order-intermodulation ratio without decreasing far-field power density. However, this improvement comes at the cost of sacrificing beam integrity in terms of side-lobe level. Third, 3rd order intermodulation with respect to the carrier is minimized by antenna impedance matching using co-simulations of the amplifier and antenna. The second part considers the optimization of realized gain in antenna arrays. First, an antenna array driven with element-specific amplifiers with varying output impedance is examined. Changes in amplifier gain may lead to altered output impedance and increased mismatch in the antenna interface, a phenomenon often neglected. An iterative method that accounts for the change in impedance is introduced, resulting in increased realized gain. Second, a cluster array concept is proposed to achieve high coverage gain over a wider band compared to a simple patch antenna array with similar elements. The cluster array utilizes patch elements with different resonant frequencies and high inter-element coupling to achieve wide-band matching with feeding weight tuning.Item Discretized Antenna Concept(2020-08-04) Viikari, Ville; Hannula, Jari-Matti; Kormilainen, Riku; Kutinlahti, Veli-Pekka; Lehtovuori, Anu; Luomaniemi, Rasmus; Saarinen, Tapio; Department of Electronics and Nanoengineering; Ville Viikari Group; Department of Electronics and NanoengineeringAll electrical properties of an antenna are determined by its current distribution. It is possible to numerically solve a current distribution producing optimal performance in some sense. However, this ideal current distribution is nearly impossible to realize in practice. We propose the discretized antenna concept, which makes it possible to realize nearly optimal current distributions in practice. The method does not necessitate manual error and trial type iteration and it can be solved with many design goals. In this paper, we describe the design steps.Item Langaton tehonsiirto(2015-05-23) Kutinlahti, Veli-Pekka; Hänninen, Jari; Sähkötekniikan korkeakoulu; Turunen, MarkusItem Radioaaltojen käyttö energialähteenä ja tiedonsiirrossa 6G:n osana(2020-12-01) Lahti, Roope; Kutinlahti, Veli-Pekka; Sähkötekniikan korkeakoulu; Turunen, MarkusItem Symmetrointimuuntaja spiraaliantennille Airfence-järjestelmään(2019-12-02) Nieminen, Seppo; Kutinlahti, Veli-Pekka; Sähkötekniikan korkeakoulu; Turunen, MarkusItem Tutkateknologia ilmailussa(2020-05-21) Haapaniemi, Rasmus; Kutinlahti, Veli-Pekka; Sähkötekniikan korkeakoulu; Turunen, MarkusItem Vahvistimien epälineaaristen ominaisuuksien tutkiminen load pull -mittauksen avulla.(2022-12-02) Saren, Mikko; Kutinlahti, Veli-Pekka; Sähkötekniikan korkeakoulu; Turunen, Markus
