Methodology for broadband matching of electrically small antenna using combined non-Foster and passive networks

Introduction. Non-Foster elements (NFEs) mimic behavior of hypothetical negative inductors or capacitors in a certain frequency band. NFEs are used to compensate reactance of conventional inductors and capacitors that allows designing broadband microwave devices. To realize NFEs, active circuits referred to as negative impedance converters (NICs) are employed to convert the load impedance into the negative input impedance. The conversion error, caused by non-optimal choice of NIC parameters and non-idealities of NIC components, limits the accuracy and operating bandwidth of NFEs. The necessity to account for many factors, which indirectly and oppositely impact the final result, and unavailability of a universal design methodology complicate the design of NFEs significantly. As a result, broadband NFE characteristics differ from the target ones remarkably that limits practical applications.Aim. Elaboration of a design methodology to compensate the Linvill’s NIC conversion error and realize high-accuracy broadband negative inductors.Materials and methods. Influence of NIC constituent parameters on the negative inductor frequency characteristics is considered. The performed analysis and the identified relationships allowed us to propose a step-by-step methodology to design negative inductors having tight tolerance over a broad frequency band. The use of a transmission line section instead of a lumped inductor in the NIC load when realizing negative inductors of high absolute values is shown to be advantageous as this allows providing better tolerance and wider bandwidth.Results. In order to demonstrate possibilities enabled by the proposed methodology, simulation results are presented for the GHz-range negative inductors with a set of inductance and tolerance values.Conclusion. The results obtained show that the proposed methodology makes it possible to compensate the conversion error without any numerical optimization and therefore to reduce the deviation of the negative inductance from the target value in the given frequency range or to broaden the bandwidth for a given tolerable deviation of the negative inductance.

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Negative-Inertia Converters: Devices Manifesting Negative Mass and Negative Moment of Inertia

Lončar

Igrec

Babic

2022

Symmetry

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Negative inertia is an unusual and counter-intuitive property of matter, extensively investigated in some of the most exotic branches of physics and engineering at both macroscopic and microscopic levels. Such an exotic property promises a wide range of applications, from Alcubierre drive to acoustic wave manipulation. Here, a novel approach to the realization of negative inertia and the concept of negative-inertia converters are introduced for both translational and rotational motion. The proposed devices, capable of exhibiting negative mass and negative moment of inertia, base their operational principle on actuating the loading inertia, concealed within the housing of the device, synchronously with the displacement of the housing itself. Negative-inertia converters share many similarities with negative-impedance converters, including their proneness to instability. Thus, an equivalent circuit model of the proposed devices is developed and simulated in lossless and lossy environments. Friction, unavoidable in every practical system, is found to be the main cause of instability. The derived closed-form stability condition suggests that the effective inertia of a system containing a negative-inertia converter must remain positive to ensure the stability. Despite this limitation, negative-inertia converters may become the key elements in applications requiring reduction of an object’s inertia.

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Methodology for broadband matching of electrically small antenna using combined non-Foster and passive networks

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Cited by 3 publications

References 15 publications

Bandwidth and Stability of Reflection Amplifiers for Intelligent Reflecting Surfaces

Bandwidth and Stability of Reflection Amplifiers for Intelligent Reflecting Surfaces

A Methodology to Design Broadband Negative Inductors with Tight Tolerance for Microwave Applications

Negative-Inertia Converters: Devices Manifesting Negative Mass and Negative Moment of Inertia

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