Narrow-band Impedance Matching Research Articles

Design and Analysis of Dual Narrow Band MIMO (DNB-MIMO) Antenna for IoT Applications

A compact DNB-MIMO antenna design and analysis for IoT application was proposed. The antennaradiator consists of 2 L-shaaped quarter-wavelengths and inverted 7-shaped radiators with a microstrip feed line, and partial ground plane with a size of 32 × 15 mm2. This antenna achieves a higher quality factor (Q > 10) and narrow band impedance matching at the central frequencies of 1.8 GHz and 2.4 GHz bands with approximately 8.2% and 6.2% bandwidth respectively. The suitability of the designed antenna for IoT applications is verified through the hosting device model. The proposed 4-port MIMO antenna has an overall size of 60 × 60 ×1.6 mm3, and it is printed on an FR4 substrate. The diversity add comma such as ECC, DG, TARC, MEG, and CCL, are calculated and there values are < 0.19, 9.85 dB, < -25 dB, < -6 dB, < 0.19 bits/Hz/s, respectively, within the limits. The proposed antenna is integrated with the Zigbee module (lowercase) to analyze the performance for IoT applications at 2.4 GHz

Double-Conversion, Noise-Cancelling Receivers Using Modulated LNTAs and Double-Layer Passive Mixers for Concurrent Signal Reception With Tuned RF Interface

A double-conversion, noise-cancelling receiver architecture is presented that consists of a double-layer mixer-first branch and two quadrature-modulated LNTA branches. The two layers of passive mixing in the mixer-first branch up-convert the low-pass, baseband impedance and create concurrent, narrowband impedance matching at (F <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LO</sub> ±F <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">IF</sub> ), as well as concurrently receive signals around these two RF carriers while rejecting spurious responses without using any IF filters. To improve the noise performance, quadrature-modulated LNTA branches are incorporated to allow frequency-translational, noise cancellation for better receiver sensitivity. Double conversion is achieved in the LNTA branches by periodically varying the LNTA transconductance and current-mode, passive mixing. A generalized, linear time-varying (LTV) analysis of the receiver is presented and verified with behavioral-model simulation results.

Design of compact dual-polarized multiband MIMO antenna using near-field for IoT

This paper presents the integration of the unlicensed ultra-wideband (UWB) with the existing bands like the 1.9 GHz long‐term‐evolution (LTE) band and 2.4 GHz industrial scientific and medical (ISM) band to cater for the diverse need of the upcoming internet of things (IoT) technology. The designed compact triband antenna has a dimension of 33 × 18 mm2 (i.e. 0.2λ0 × 0.11λ0, where λ0 is calculated at 1.89 GHz in the free space). This antenna provides high-quality factor (Q) and narrow-band impedance matching at the 1.9 and 2.4 GHz bands with about 2.9% and 4.7% bandwidth respectively, which is sufficient for those IoT applications, which are supposed to support low data rate communication. Further, the triband antenna is found to be effective for IoT as the hosting effect is within the tolerable range. Finally, multiband polarization diversity antenna is designed having a size of only 33 × 57.25 mm2 (0.2λ0 × 0.36λ0) to combat the depolarization effect of signals in the indoor environment. Near-field simulations are carried out to determine the best position/orientation of MIMO elements in order to improve port-to-port isolation and envelope-correlation-coefficient (ECC). The minimum isolation and maximum ECC are found to be 14.2 dB and 0.0471, respectively across all the operating frequency bands.

Modified Q-Based Real Frequency Design of Narrowband Impedance Equalizer with Complex Terminations

In this paper, real frequency design equations of narrowband impedance matching network with complex terminations are derived; which are used to design L, Pi and T type of networks. In the approach, there is no need to have termination models with component values, it is enough to have measurement values of termination impedances. A few examples are solved to exhibit the merits and application of the derived equations.

Excellent Microwave Absorption Properties Derived from the Synthesis of Hollow Fe₃o₄@Reduced Graphite Oxide (RGO) Nanocomposites.

Magnetic nanoparticles, such as Fe3O4 and Co3O4, play a vital role in the research on advanced microwave absorbing materials, even if problems such as high density and narrow band impedance matching are still unsolved. Herein, the study of lightweight hollow Fe3O4@reduced graphite oxide (RGO) nanocomposites synthesized via the solvothermal method is presented. The microstructure and crystal morphology of the materials were characterized by X-ray diffractometer (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) analyses. Single crystalline hollow Fe3O4 spheres were grown onto RGO flakes, leading to the formation of heterojunction, which further influenced the microwave absorption properties. The latter were evaluated by standard microwave characterization in the frequency range of 2–18 GHz. It was found that, for a specific Fe3O4@0.125 g RGO composite, the minimum reflection loss can reach −41.89 dB at 6.7 GHz, while the reflection loss was less than −10 dB from 3.4 GHz to 13.6 GHz for a nanocomposite sample thickness in the range of 1–4 mm. The combination of these two materials thus proved to give remarkable microwave absorption properties, owing to enhanced magnetic losses and favorable impedance matching conditions.

A fully integrated rf front end for DVB‐SH

AbstractThis article describes a RF front end for DVB‐SH (2.17–2.2 GHz) implemented in UMC CMOS 90 nm process. This receiver includes a low noise amplifier (LNA), a single‐to‐differential converter, and a mixer. The LNA is based on cascode topology combined with a narrow band impedance matching and LC tank load. The single‐to‐differential converter generates a pair of differential output signals from a single input, which have balanced amplitude and phase. This converter is followed by a Gilbert cell based quadrature mixer. The measurements show a conversion gain of 15.7–15.5 dB, an input return loss (S11) of −12 dB, and an output compression point of 1.92 dBm. This receiver has a simulated noise figure of 2.2 dB. This combination draws 22 mW from a 1.2‐V supply. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:1944–1949, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26974

Accurate measurement method for characterisation of RF impedance tuners

The design and measurement of a compact narrowband impedance matching network is presented. The device has been realised in hybrid technology: coplanar waveguide transmission lines and surface-mounted components. The experimental results were carried out through two different measurement methods, a traditional approach and a new faster, simpler one giving the same results. They show that complex impedances with magnitudes varying from 6.3 to 1120 Ω can be matched with a 50% bandwidth around the centre frequency.

Review of narrowband impedance-matching limitations

Many antennas can be characterized by their radiation Q (the ratio of reactance to radiation resistance). A classic problem is determining the maximum possible bandwidth, constrained by the maximum permissible reflection magnitude, and the number of tuned circuits in the impedance-matching circuit. This paper presents a review on theoretical limitations of narrowband impedance matching.