Narrow Results

We design a structure to achieve a function of polarization-independent multi-band unidirectional reflectionlessness in a non-Hermitian metamaterial system based on the Fabry-Pérot resonance. All contrast ratios of reflectance at 198 THz, 214.2 THz, and 232.65 THz are 0.99. The unidirectional reflectionless peak position remains almost unchanged with increasing polarization angles. Besides, the structure can also be used to realize the unidirectional reflectionless phenomenon in the incident angle range of 0–30${}^{\circ }$, which may provide great convenience for experimental operations.

A multi-band perfect metamaterial absorber (MA) based on a cylindrical waveguide with polarization independency is numerically presented and investigated in detail. The proposed absorber has a very simple configuration, and it operates at flexible frequency ranges within the microwave frequency regime by simply tuning the dimensions of the structure. The maximum absorption values are obtained as 99.9%, 97.5%, 85.8%, 68.2% and 40.2% at the frequencies of 1.34 GHz, 2.15 GHz, 3.2 GHz, 4.31 GHz and 5.41 GHz, respectively. The numerical studies verify that the proposed model can provide multi-band perfect absorptions at wide polarization and incident angles due to its rotational symmetry feature. We have also realized sensor and parametric study applications in order to show additional features of the suggested model. The suggested MA enables myriad potential applications in medical technologies, sensors and in defense industry etc.

In this paper, a cross-coupled complementary inductance–capacitance voltage controlled oscillator (LCVCO) with low phase noise and wide tuning range is presented. It has a multi-band topology and was fabricated with RF CMOS technology. For the purpose of lowering the K_VCO and reducing the nonlinearities of varactors, the sizes of the varactors are set small. Also noise filtering technique is adopted to minimize up-conversion of the low frequency noise as well as down-conversion of the high frequency noise, thus the phase noise performance of the VCO is greatly improved. Simulation and experimental results indicate that the LCVCO displays a phase noise of -126.1 dBc at 900 kHz offset in worst case with a tuning range from 1.76 to 1.96 GHz.

In this paper, a differential multi-band CMOS low noise amplifier (LNA) is proposed that is operated within a range of 1500–2700 MHz with input matching capacitor switching and gain flatness performance enhancement technique. Traditional multi-band LNAs have poor performances on gain flatness performance. Therefore, we propose a new multi-band LNA which obtain good gain flatness performance by integrating the characteristics of the transistor trans-conductance and LC resonant load. The new LNA can also achieve a tunable frequency at different matching capacitance conditions. The post-layout simulation results shows that the voltage gain is between 19.3 dB and 22.4 dB, the NF is less than 2.5 dB, and the 1-dB compression point is about -5.1 dBm. The LNA consumes 17.79 mW under 1.8 V supply voltage in TSMC 0.18-um RF CMOS process.

This paper describes the design of a novel cascode-grounded tunable active inductor and its application in an active band-pass filter (BPF) suitable for multi-band radio frequency (RF) front-end circuits. The proposed active inductor circuit uses feedback resistance to improve the equivalent inductance and the quality factor. The novelty of this work lies on the use of a few number of multi-finger transistors, which allows reducing strongly the power consumption and the silicon area. In other words, we demonstrate that the use of variable P-type Metal-Oxide-Semiconductor (PMOS) resistor and controllable current source have a good potential for wide tuning in terms of inductance value, quality factor and frequency operation. The RF BPF is realized using the proposed active inductor with suitable input and output buffer stages. The tuning of the center frequency for multi-band operation is achieved through control voltages. The designed active inductor and RF BPF have been implemented in a standard 0.13$\mu$m Complementary Metal Oxide Semiconductor (CMOS) technology. The simulation results are compared between schematic and post-layout design for inductance value, quality factor, transmission coefficient S21 and noise. This design yields encouraging results: the inductance value can be tuned from 10.94 to 44.17nH with an optimal quality factor around 2,581. In addition, the center frequency of the BPF can be tuned between 2 and 4.84GHz with an average insertion loss of $10.92\pm 0.31$dB. Throughout this range, the noise figure is between 10.49 and 9.22dB with an input referred 1dB compression point of $-0.25$dBm and IIP3 of 7.36dBm. The filter occupies 25.43$\mu \mathrm{\text{m}}\times 21.56\mu$m of active area without pads and consumes between 2.38 and 2.84mW from a 1V supplying voltage.

In this paper, a compact reconfigurable tri-band/quad-band monopole antenna is presented. To achieve the multi-band behavior, two right-angled triangles were etched in a conventional rectangular patch, and a partial ground plane is used. Moreover, the proposed multi-band antenna is printed on a low cost FR4 epoxy with compact dimensions of 0.23${\lambda }_0\times 0.23{\lambda }_0\times 0.012{\lambda }_0$, where ${\lambda }_0$ is calculated at the lowest resonance frequency. To provide frequency agility, a metal strip which acts as PIN diode was embedded in the frame of the modified patch. The tri-band/quad-band antenna performance in terms of reflection coefficient, radiation patterns, peak gain and efficiency was studied. The measured results are consistent with the simulated results for both cases. The simple structure and the compact size of the proposed antenna could make it a good candidate for multi-band wireless applications.

In this paper, a highly efficient tree-shaped fractal antenna with multi-broadband resonance characteristics is proposed. The proposed antenna exhibits broad operating bandwidth, high gain, and high efficiency characteristics due to the suggested modifications in the antenna geometry. The suggested circular patch is modified by introducing slots in the form of a tree-shaped fractal structure, and the partial ground plane is modified by incorporating a narrow rectangular slot. The proposed antenna is designed on an FR4 substrate of $40\times 25.05\times 1.6$mm³. The prototype of the proposed antenna has been fabricated and tested to justify the simulation results. The measurement results are in good agreement with the simulation that validates the multi-broadband design approach of the proposed fractal antenna. As per the measurement results, the proposed antenna operates at four distinct bands with $-$10dB impedance bandwidths of 600MHz (2.2–2.8) GHz, 1070MHz (3.3–4.37) GHz, 2550MHz (4.75–7.3) GHz, and 2200MHz (9.7–11.9) GHz. Furthermore, a high peak gain of 10.23dB and a peak radiation efficiency of 96.65% are recorded for the suggested fractal antenna. The suggested compact bandwidth enhanced multi-band antenna can be useful for several wireless communication systems such as wireless fidelity (Wi-Fi), wireless local area network (WLAN), Bluetooth, long-term evolution (LTE), C, S and X bands.

This paper describes the requirements on RF filtering derived from multi-band, multi-mode RF front ends for cellular phone applications. Drivers are forward integration – e.g. from PA function via transmit front-end to a fully integrated radio – and new influences are introduced by new requirements of 3G systems and the integration of complementary access (e.g., Bluetooth; WLAN, GPS, DVB-H). Filter components such as SAW and BAW filters have to solve several aggravated requirements simultaneously. New technologies are required to follow the demand for improved RF performance, reduced PCB area consumption, and continuously decreased overall component costs.