Electrically small metamaterial-inspired antennas with active near field resonant parasitic elements: From theory to practice

© 2017 Euraap. By augmenting several classes of metamaterial-inspired near-field resonant parasitic (NFRP) electrically small antennas (ESAs) with active (non-Foster) circuits, we have achieved performance characteristics surpassing their fundamental passive bounds. The designs not only have high radiation efficiencies, but they also exhibit large frequency bandwidths, large beam widths, large front-to-back ratios, and high directivities. Furthermore, the various initially theoretical and simulated designs have led to practical realizations. These active NFRP ESAs will be reviewed and recently reported designs will be introduced and discussed

Overcoming traditional electrically small antenna tradeoffs with meta-structures

© 2017 Euraap. Metamaterial-inspired near-field resonant parasitic (NFRP) electrically small antennas (ESAs) have been designed and experimentally validated to have not only high radiation efficiencies, but also multi-functionality, large bandwidths, high directivities and reconfigurability. These expanded capabilities have been attained by introducing more complex meta-structures, i.e., multiple NFRP elements loaded with fixed and tunable lumped elements, as well as active circuits. Different classes of passive and active NFRP ESAs that have successfully produced these effects will be reviewed, and several recently reported ESA systems will be introduced and discussed

Compact hyper-band printed slot antenna: Design and experiments

© 2014 European Association on Antennas and Propagation. A compact hyper-band printed antenna design is designed numerically and measurements of a fabricated prototype confirm the predicted 10:1 input impedance bandwidth and radiation characteristics. It is based on an elliptical-slot antenna augmented with a parasitic oval patch and driven with a specially engineered microstrip-line-fed elliptical tuning fork element. The total size of the final optimized antenna is 30 × 40 mm2; it exhibits a -10-dB impedance bandwidth from 2.26 to 22.18 GHz. While the hyper-band performance could be used for high fidelity pulse applications, the antenna also covers the entire ultra-wideband (UWB) spectral range from 3.1-10.6 GHz

Compact printed ultra-wideband antenna: corrugated monopole augmented with parasitic strips

© 2016 Informa UK Limited, trading as Taylor & Francis Group. A novel compact microstrip line-fed ultra-wideband (UWB) antenna is reported in this paper. The antenna consists of a corrugated half-ellipse monopole and three strips that act as near-field resonant parasitic (NFRP) elements. The entire UWB band (3.1–10.6 GHz) is covered from a very compact size: 19 mm × 10 mm. Two of the NFRP strips are utilized to cover more effectively the lower portion of the UWB frequency range; the third one improves the broadside gain values by 3.28 dB in the upper portion. As a consequence, this compact design maintains a stable radiation performance over the entire UWB band

Electrically Small, Broadside Radiating Huygens Source Antenna Augmented with Internal Non-Foster Elements to Increase Its Bandwidth

© 2002-2011 IEEE. A broadside radiating, linearly polarized, electrically small Huygens source antenna system that has a large impedance bandwidth is reported. The bandwidth performance is facilitated by embedding non-Foster components into the near-field resonant parasitic elements of this metamaterial-inspired antenna. High-quality and stable radiation performance characteristics are achieved over the entire operational bandwidth. When the ideal non-Foster components are introduced, the simulated impedance bandwidth witnesses approximately a 17-fold enhancement over the passive case. Within this-10-dB bandwidth, its maximum realized gain, radiation efficiency, and front-To-back ratio (FTBR) are, respectively, 4.00 dB, 88%, and 26.95 dB. When the anticipated actual negative impedance convertor circuits are incorporated, the impedance bandwidth still sustains more than a 10-fold enhancement. The peak realized gain, radiation efficiency, and FTBR values are, respectively, 3.74 dB, 80%, and 28.01 dB, which are very comparable to the ideal values

A 28-GHz, multi-layered, circularly polarized, electrically small, Huygens source antenna

© 2017 IEEE. A 28 GHz, multi-layered, circularly-polarized (CP), Huygens source electrically small antenna (ESA) is presented. The CP radiation is realized by integrating two orthogonal linearly polarized Huygens source EASs into one with an asymmetrical arc strip feed providing the necessary 90° phase difference. Finally, the CP Huygens source ESA exhibits the properties: ka = 0.942; 1.41% FBW-10dB with a 0.47% 3-dB axial ratio (AR) fractional bandwidth; and peak realized gain, FTBR, and radiation efficiency values are 2.03 dBi, 26.72 dB, and 73.4%, respectively. To confirm its efficacy for on-body applications, the specific absorption rate (SAR) values of the Huygens source ESA is evaluated and found to be very low

Compact hyper-band printed slot antenna with stable radiation properties

A compact hyper-band (> 10:1 impedance bandwidth) printed antenna design is investigated numerically and experimentally. It is based on an elliptical-slot antenna augmented with a parasitic oval patch and driven with a specially engineered microstrip-line-fed elliptical tuning fork element. The parasitic and driven elements are adjusted along with the elliptical slot to create additional resonance modes; adjust the coupling strengths among all of the design components; facilitate the overlap of adjacent resonance modes; and fine tune the input impedance. The total size of the final optimized antenna is only 30×40 mm2. It exhibits a -10-dB impedance bandwidth from 2.26 to 22.18 GHz. Desirable radiation performance characteristics, including relatively stable and omni-directional radiation patterns, are obtained over this range. A prototype was fabricated and tested. The experimental results confirm the predicted input impedance bandwidth and radiation characteristics. While the hyper-band performance could be used for high fidelity short pulse applications, the antenna could also be used for multi-band operations from 3.1-10.6 GHz since it covers that entire ultra-wideband (UWB) spectral range. © 1963-2012 IEEE

The Design of a Compact, Wide Bandwidth, Non-Foster-Based Substrate Integrated Waveguide Filter

© 2018 IEEE. A compact, wideband, half-mode substrate integrated waveguide (HM-SIW) filter with internal non-Foster element is demonstrated. First, its passive version is simulated and measured. Next, by integrating an ideal tunable capacitor at the end of the central stub of the HM-SIW resonator, the frequency-agile characteristic of the tunable HM-SIW filter is investigated. Finally, a negative impedance converter (NIC) is developed to replace this tunable capacitor to design a new nonFoster filter. The non-Foster-based HM-SIW filter was realized. Its measured results indicate that it has an operational fractional bandwidth of 10.8% and an electrical size 0.118 × 0.292 λ g 2, which is a 3.93 times bandwidth increase and a 12% electrical size reduction compared to its passive, fixed capacitance version

Experimentally Validated, Planar, Wideband, Electrically Small, Monopole Filtennas Based on Capacitively Loaded Loop Resonators

© 2016 IEEE. Two planar efficient wideband electrically small monopole filtennas are presented. The first one directly evolved from a common planar capacitively loaded loop (CLL)-based filter. This filtenna possesses a flat realized gain response within the operational band and good band-edge selectivity. The second filtenna consists of a driven element augmented with a CLL structure and with slots etched into its ground plane. It expands the fractional impedance bandwidth of the first case from 6.28% up to 7.9%. It too has a gain response that remains flat over its operational bandwidth and even higher band-edge selectivity. Both filtennas are electrically small: ka < 1. The experimental results, which are in good agreement with their simulated values, demonstrate that both filtennas exhibit excellent impedance matching, high radiation efficiency, flat gain response, and steep skirts at both band edges, as well as producing monopole radiation patterns that are uniform and nearly omnidirectional in their H-planes

Circularly polarized electrically small antennas for emerging wireless applications

© Institution of Engineering and Technology.All Rights Reserved. This paper introduces three circularly-polarized (CP) electrically small antennas for emerging wireless applications including wireless power transfer (WPT), Internet-of-Things (IoT), and Device-to-Device (D2D) communications in future fifth generation (5G) systems. First, an electrically small Huygens CP (HCP) antenna operating at L-band frequencies is presented that is facilitated by two near-field resonant parasitic (NFRP) elements, a crossed Egyptian axe dipole (EAD) pair and a crossed capacitively loaded loop (CLL) pair. The HCP antenna is electrically small (ka = 0.73), low profile (~ 0.04°0), and has decent cardioid-shaped radiation patterns with a broad half power beamwidth (>120°). It is attractive for many WPT and body-centric wireless sensor network applications. Second, with the rapid development of 5G wireless networks, a corresponding 28 GHz electrically small HCP antenna is reported. The overall size of this antenna is only p (1.5)2 × 1 ˜ 7 mm3 (ka = 0.94), which can be readily integrated into the various compact platforms anticipated for 5G IoT devices. Third, unlike the above two antennas that radiate uni-directional patterns, a compact 28 GHz omni-directional CP (OCP) antenna is presented for D2D communications in future 5G systems. It is electrically small (ka = 0.95), easy to fabricate, and its performance characteristics cover the entire FCC-specified 5G, 27.5 to 28.35 GHz band