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Methodology for Broadband Matching of Electrically Small Antenna using combined Non-Foster and Passive Networks

DOI:10.1007/s10470-020-01672-3
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Saadou Almokdad at Atomic Energy and Alternative Energies Commission
Saadou Almokdad
R. Lababidi at ENSTA Bretagne
R. Lababidi
Marc Le Roy at Université de Bretagne Occidentale
Marc Le Roy
Sawsan Sadek at Lebanese University
Sawsan Sadek
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Abstract and Figures

Decreasing the electric length of an antenna results in increasing its input reactance that becomes greater than its input resistance, resulting in a significant rise in its quality factor and in a drastic reduction of its potential operating bandwidth. For such small antennas, namely ESA for Electrically Small Antenna, passive matching is restricted by the gain-bandwidth theory, providing narrow bandwidths and/or poor gain. This limitation can be overtaken by using antenna matching networks based on non-Foster components. In previous studies, non-Foster components are used to cancel the reactance part of the ESA, and then passive matching may be introduced to transform the net input impedance toward 50Ω, which leads to an increase in the bandwidth. In this paper, a design methodology is put forward on three different topologies all based on combined passive and active matching networks. A described step-by-step design to decrease the antenna quality factor is discussed. A comparison is made between these topologies along with a discussion on their limitations and ability to increase the bandwidth and radiation efficiency of ESA. The third topology presented in this paper is a novel one that proposes a three-stage matching network and exhibits both the widest matched bandwidth and an increase in the efficiency of the whole system compared to previous approaches. In order to make this comparison, a new indicator to estimate the whole system radiated power efficiency is introduced and validated by comparison with a full EM simulation. Moreover, actual implementation of the two most interesting techniques are detailed and associated measured results are carefully compared to simulations.
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Methodology for broadband matching of electrically small antenna
using combined non-Foster and passive networks
Saadou Almokdad
1,2
•Raafat Lababidi
1
•Marc Le Roy
1
•Sawsan Sadek
3
•Andre
´Pe
´rennec
1
•
Denis Le Jeune
1
Received: 19 December 2019 / Revised: 27 April 2020 / Accepted: 2 June 2020 / Published online: 6 June 2020
Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract
Decreasing the electric length of an antenna results in increasing its input reactance that becomes greater than its input
resistance, resulting in a significant rise in its quality factor and in a drastic reduction of its potential operating bandwidth.
For such small antennas, namely ESA for Electrically Small Antenna, passive matching is restricted by the gain-bandwidth
theory, providing narrow bandwidths and/or poor gain. This limitation can be overtaken by using antenna matching
networks based on non-Foster components. In previous studies, non-Foster components are used to cancel the reactance
part of the ESA, and then passive matching may be introduced to transform the net input impedance toward 50X, which
leads to an increase in the bandwidth. In this paper, a design methodology is put forward on three different topologies all
based on combined passive and active matching networks. A described step-by-step design to decrease the antenna quality
factor is discussed. A comparison is made between these topologies along with a discussion on their limitations and ability
to increase the bandwidth and radiation efficiency of ESA. The third topology presented in this paper is a novel one that
proposes a three-stage matching network and exhibits both the widest matched bandwidth and an increase in the efficiency
of the whole system compared to previous approaches. In order to make this comparison, a new indicator to estimate the
whole system radiated power efficiency is introduced and validated by comparison with a full EM simulation. Moreover,
actual implementation of the two most interesting techniques are detailed and associated measured results are carefully
compared to simulations.
Keywords Non-Foster Passive matching Quality factor Electrically small antenna
1 Introduction
The demand for wide-band small antennas is steadily
increasing for future wireless communication systems, due
to the need of compact multi-function and multi-standard
devices. Electrically small antennas (ESA) are thus
required due to the limited space available in the structures
such as electronic mobile devices (5G), IoT (Internet of
Things), medical equipment, etc. However, practical
application in today’s electronic systems is limited by their
fundamental tradeoff between bandwidth and efficiency
using passive impedance matching techniques [1]. Non-
Foster circuits (NFCs) are active circuits that promise to
break the fundamental tradeoffs between size, operating
frequency and bandwidth for electrically small antennas
[2], [3].
An antenna is considered to be an ESA when it satisfies
the following condition: ka \0.5, where k is the wave
number and a is the radius of a hypothetical sphere
enclosing the antenna [4].
Furthermore, ESAs famously suffer from high quality
factor Q because of their high reactance value compared to
their small resistive value, resulting in storing the input
power in their near field and a small portion radiates in
their far field [5]. Wheeler and Chu [6] have provided
&Saadou Almokdad
Saadou-ali-almokdad@hotmail.com
1
Lab-STICC (UMR CNRS 6285), UBO, ENSTA-Bretagne,
Brest, France
2
Doctoral School of Science and Technology, Lebanese
University, Hadath, Lebanon
3
Faculty of Technology, Lebanese University, Saida, Lebanon
123
Analog Integrated Circuits and Signal Processing (2020) 104:251–263
https://doi.org/10.1007/s10470-020-01672-3(0123456789().,-volV)(0123456789().,-volV)
Content courtesy of Springer Nature, terms of use apply. Rights reserved.
... Such an element requires an additional power source and does not obey Foster's reactance theorem [18], and thus it is known as a non-Foster element. The use of non-Foster elements has been proposed not only for the realization of broadband dispersionless metamaterials [20,21], but for the reduction of parasitic losses [22], improvement of device characteristics [22], filtering [23], realization of oscillators [24], phase shifters [25], broadband matching of small antennas [26][27][28][29][30][31], the design of broadband microwave [32] and reflection amplifiers [33,34], and realization of parity-time symmetric systems [35,36]. In this article we transfer the concept of electrical NICs to mechanical systems and propose novel concept of mechanical negative-inertia converters (NICs), able to produce negative mass in a fundamentally different manner compared to acoustic metamaterials. ...
Negative-Inertia Converters: Devices Manifesting Negative Mass and Negative Moment of Inertia
Article
Full-text available
  • Mar 2022
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.
Wide-band Active Tunable Phase Shifter Using Improved Non-Foster circuit
Conference Paper
Full-text available
  • Dec 2018
Non-Foster impedance matching of an electrically small loop antenna for biomedical telemetry
Conference Paper
Full-text available
  • Nov 2017
Réseau d'antennes compact, super directif et large-bande associé aux éléments Non-Foster
Article
Full-text available
  • May 2017
Les performances des antennes électriquement petites ou compactes sont limitées par les lois fondamentales de la physique. L'introduction d'éléments actifs au sein d'une structure d'antenne constitue une opportunité pour dépasser ces limites. Les éléments Non-Foster sont généralement utilisés afin d'améliorer l'adaptation d'impédance des antennes miniatures. Dans ce papier, les éléments Non-Foster sont proposés comme une méthode innovante pour réaliser des antennes à la fois compactes et fortement directives sur une large bande passante. L'étude est menée dans la bande UHF, centrée à 1.2 GHz en utilisant un réseau de deux antennes dipolaires associées à des éléments Non-Foster.
A Non-foster Matching Circuit for an Ultra-wideband Electrically Small Monopole Antenna
Conference Paper
  • Feb 2019
In this paper, a negative-capacitance non-foster circuit (NFC) is designed to match an electrically small monopole antenna with a height of 300 mm. Since the effectiveness of an electrically small antenna is severely limited by gain-bandwidth theory due to high-Q impedances, a non-foster circuit is proposed to overcome this limitation. The proposed circuit is verified by using co-simulation based on HFSS and ADS, and the results indicate that the electrically small monopole antenna is well matched to the designed NFC with a bandwidth of 173% which ranges from 16 MHz-222MHz. Index Terms-Monopole antenna, negative-capacitance non-foster circuit, super-band electrically small antenna.
Non-foster broadband matching networks for electrically-small antennas
Conference Paper
  • Nov 2016
A Reactance Theorem
Article
  • Jan 1924
Broadband non-Foster matching of an electrically small loop antenna
Conference Paper
  • Jul 2012
Electrically small antennas have a theoretical limit to the maximum bandwidth-efficiency product that can be achieved, as derived by Wheeler and Chu. This can be overcome using non-Foster matching (active matching), as is shown in this paper for an electrically small loop antenna. A floating negative inductor was simulated and the full matching network simulation demonstrates that the bandwidth of the small antenna increases to 2.9 times the Wheeler-Chu limit.
Realizing Non-Foster Reactive Elements Using Negative-Group-Delay Networks
Article
An intimate relation is established between non-Foster reactive elements and loss-compensated negative-group-delay (NGD) networks. It is shown that any possible network configuration containing a class of non-Foster elements operates as an NGD network. Likewise, it is demonstrated that a loss-compensated NGD network represents a reactive network with a non-Foster behavior. Consequently, these two properties can be intimately linked together and NGD networks can be utilized to implement non-Foster elements, such as negative capacitors and inductors. This result introduces another perspective in realizing non-Foster reactive elements, leading to new designs that are well behaved and more predictable in terms of stability and operation than traditional designs using negative impedance inverters and negative impedance converters. Based on this concept, loss-compensated NGD networks are proposed for realizing high-quality non-Foster reactive elements. Furthermore, entirely passive non-Foster elements with a limited quality ( Q) factor are proposed for which the minimum Q factor and the maximum achievable bandwidth are inversely related. It is shown that the design of non-Foster reactive elements using NGD networks can lead to the realization of standalone unilateral non-Foster reactive elements in a certain bandwidth. Examples of such non-Foster reactive elements and networks are demonstrated experimentally and shown to be stable.
Network Analysis and Feedback Amplifier Design
Article
  • Jan 1945
Physical Limitations of Omni‐Directional Antennas
Article
  • Jan 1949
The physical limitations of omni‐directional antennas are considered. With the use of the spherical wave functions to describe the field, the directivity gain G and the Q of an unspecified antenna are calculated under idealized conditions. To obtain the optimum performance, three criteria are used, (1) maximum gain for a given complexity of the antenna structure, (2) minimum Q, (3) maximum ratio of G/Q. It is found that an antenna of which the maximum dimension is 2a has the potentiality of a broad band width provided that the gain is equal to or less than 4a/λ. To obtain a gain higher than this value, the Q of the antenna increases at an astronomical rate. The antenna which has potentially the broadest band width of all omni‐directional antennas is one which has a radiation pattern corresponding to that of an infinitesimally small dipole.