scholarly journals An RF-MEMS-Based Digitally Tunable SIW Filter in X-Band for Communication Satellite Applications

2019 ◽  
Vol 9 (9) ◽  
pp. 1838 ◽  
Author(s):  
Abbas El Mostrah ◽  
Andrei Muller ◽  
Jean-François Favennec ◽  
Benjamin Potelon ◽  
Alexandre Manchec ◽  
...  
Keyword(s):  
Tuning Range ◽  
Rf Mems ◽  
Frequency Control ◽  
Frequency Range ◽  
Digital Frequency ◽  
X Band ◽  
Satellite Applications ◽  
Waveguide Filter ◽  
Functional States ◽  
Commercial Off The Shelf

This paper presents a digitally tunable SIW (substrate integrated waveguide) filter designed for X-band, based on RF-MEMS (radio frequency micro-electrical-mechanical systems) technology. Four commercial off-the-shelf RF-MEMS single-pole single-throw (SPST) switches were directly mounted on the upper surface of the filter, with metallic tuning posts specifically located within each cavity to define the potential achievable frequency range. Fabricated on standard alumina substrate, the design of the filter and the biasing network enabled fine digital frequency control of up to four functional states by the inclusion of wire bondings between each switch and the substrate. A relative tuning range of 2.3% was achieved between the lower and upper discrete states of 2.76% and 2.89% in the 3 dB fractional bandwidths.

Design and Analysis of a Novel MEMS Variable Capacitor for RF Applications

2008 ◽  
Author(s):  
Qing Rao ◽  
Jun Yao ◽  
Li Zhang ◽  
Dajia Wang ◽  
Mohua Yang
Keyword(s):  
Return Loss ◽  
Tuning Range ◽  
Rf Mems ◽  
Wide Frequency Range ◽  
Bottom Plate ◽  
Cantilever Beams ◽  
Frequency Range ◽  
Fixed Plate ◽  
Variable Capacitor ◽  
Mechanical Suspension

A novel electrostatic RF MEMS variable capacitor consisting of a suspended top plate and two fixed bottom electrodes is presented. The fixed bottom electrodes are constructed by an inner fixed plate and an outer fixed plate. The inner fixed bottom plate is designed to provide electrostatic actuation for capacitance tuning and the outer one is coupled with the top plate to form a variable capacitor. The mechanical suspension of the top plate is served by four L-shaped cantilever beams, the spring constant of which has been analyzed. The characteristics of the proposed device have been analyzed through FEA software IntelliSuite and HFSS, and an extended tuning range of 78.9% is obtained. The achievable pull-in voltage is 20.2V. This capacitor operates over a wide frequency range from 1GHz to 20GHz with the return loss lower than 0.16 dB. Its quality factor is 119 at 5GHz when the applied voltage is zero.

RF MEMS Extended Tuning Range Varactor and Varactor Based True Time Delay Line Design

PIERS Online ◽  
2008 ◽  
Vol 4 (4) ◽  
pp. 433-436 ◽  
Author(s):  
Yaping Liang ◽  
Calvin W. Domier ◽  
Neville C. Luhmann, Jr.
Keyword(s):  
Time Delay ◽  
Delay Line ◽  
Tuning Range ◽  
Rf Mems ◽  
True Time Delay ◽  
True Time ◽  
Line Design

scholarly journals A Novel Fast-Locking ADPLL Based on Bisection Method

Electronics ◽  
2021 ◽  
Vol 10 (12) ◽  
pp. 1382
Author(s):  
Xiaoying Deng ◽  
Huazhang Li ◽  
Mingcheng Zhu
Keyword(s):  
High Performance ◽  
Tuning Range ◽  
Frequency Control ◽  
Control Word ◽  
Cmos Process ◽  
Bisection Method ◽  
Reference Frequency ◽  
Wide Tuning Range ◽  
Cascade Structure ◽  
And Control

Based on the idea of bisection method, a new structure of All-Digital Phased-Locked Loop (ADPLL) with fast-locking is proposed. The structure and locking method are different from the traditional ADPLLs. The Control Circuit consists of frequency compare module, mode-adjust module and control module, which is responsible for adjusting the frequency control word of digital-controlled-oscillator (DCO) by Bisection method according to the result of the frequency compare between reference clock and restructure clock. With a high frequency cascade structure, the DCO achieves wide tuning range and high resolution. The proposed ADPLL was designed in SMIC 180 nm CMOS process. The measured results show a lock range of 640-to-1920 MHz with a 40 MHz reference frequency. The ADPLL core occupies 0.04 mm2, and the power consumption is 29.48 mW, with a 1.8 V supply. The longest locking time is 23 reference cycles, 575 ns, at 1.92 GHz. When the ADPLL operates at 1.28 GHz–1.6 GHz, the locking time is the shortest, only 9 reference cycles, 225 ns. Compared with the recent high-performance ADPLLs, our design shows advantages of small area, short locking time, and wide tuning range.

scholarly journals Snow dielectric properties: from DC to microwave X-band

1994 ◽  
Vol 19 ◽  
pp. 92-96 ◽  
Author(s):  
TH. Achammer ◽  
A. Denoth
Keyword(s):  
Grain Size ◽  
Dielectric Properties ◽  
Water Content ◽  
Liquid Water ◽  
Liquid Water Content ◽  
Frequency Range ◽  
Snow Density ◽  
Cold Room ◽  
X Band ◽  
Grain Size And Shape

Broadband measurements of dielectric properties of natural snow samples near or at 0°C are reported. Measurement quantities are: dielectric permittivity, loss factor and complex propagation factor for electromagnetic waves. X-band measurements were made in a cold room in the laboratory; measurements at low and intermediate frequencies were carried out both in the field (Stubai Alps, 3300 m; Hafelekar near Innsbruck, 2100 m) and in the cold room. Results show that in the different frequency ranges the relative effect on snow dielectric properties of the parameters: density, grain-size and shape, liquid water content, shape and distribution of liquid inclusions and content of impurities, varies significantly. In the low-frequency range the influence of grain-size and shape and snow density dominates; in the medium-frequency range liquid water content and density are the dominant parameters. In the microwave X-band the influence of the amount, shape and distribution of liquid inclusions and snow density is more important than that of the remaining parameters.

scholarly journals Development of a low-cost X-band meteorological radar

2021 ◽  
Author(s):  
Jan Hrach
Keyword(s):  
Material Selection ◽  
Low Cost ◽  
Technology Selection ◽  
Advantages And Disadvantages ◽  
Radar Network ◽  
X Band ◽  
Spatially Distributed ◽  
Commercial Off The Shelf ◽  
Slotted Waveguide ◽  
Small Team

<p>We have undertaken a journey to develop a small X-band radar based on widely available commercial off-the-shelf (COTS) components. We have evaluated various radar transmitters, antenna and radome designs and sizes and we are currently operating the second-largest radar network in Europe, spanning 5 countries and consisting of 30 radars.</p><p>The final solution can be deployed by a small team in two days and operated without supervision with negligible maintenance and recurring costs. With approximately 120 kilometers of effective range and high refresh rate, it might be a good fit as an early warning radar, for areas with no current radar coverage or to fill gaps in larger networks; however, due to some limitations of the X band, namely higher attenuation in spatially distributed rain, it may not be a replacement of long-range observation radars.</p><p>In this work, we present an overview of our undertakings, technical solutions we have chosen and problems we have encountered. First, we cover transmitter technology selection, and discuss advantages and disadvantages of currently available magnetron and solid-state transmitters. Then we show the evolution of our antenna design, from 1-dimensional slotted waveguide to parabolic antennas with tapered beam. </p><p>With large parabolic antennas, another problem arises: the mechanics of the radar cannot cope with the additional weight and angular momentum, thus we had to develop various mechanical supports and a custom rotator. This rotator can also tilt the antenna, effectively adding volumetric scanning; the tilting is also needed to cope with non-ideal radar locations, where the horizon is partially obscured, which are unfortunately common for a radar network with limited budget. Finally, we discuss design and material selection of our custom radomes, and present an overall experience with everyday running and maintaining the network.</p>

scholarly journals Electromagnetic Interference Shielding Efficiency in the Range 8.2-12.4 GHz of Polymer Composites with Dispersed Carbon Nanoparticles

2011 ◽  
Vol 14 (1) ◽  
pp. 55 ◽  
Author(s):  
Anna V. Gubarevich ◽  
Kazuki Komoriya ◽  
Osamu Odawara
Keyword(s):  
Carbon Nanotubes ◽  
Carbon Black ◽  
Polymer Composites ◽  
Electromagnetic Interference ◽  
Carbon Nanoparticles ◽  
Hot Press ◽  
Frequency Range ◽  
Electromagnetic Interference Shielding ◽  
X Band ◽  
Graphite Nanoparticles

In the present work, electromagnetic interference shielding properties of polymer composites with dispersed cup-stacked carbon nanotubes, graphite nanoparticles and carbon black were investigated. The polymer composites with carbon nanoparticles content from 1 to 5 w% were successfully prepared by the coagulation method, and composite sheets with thickness from 0.25 to 0.77 mm were formed by the hot press technique. The electromagnetic interference shielding efficiency measured in the frequency range of 8.2~12.4 GHz (X-band) of cup-stacked carbon nanotubes/polymer composite was considerably higher than that of carbon black and graphite nanoparticles polymer composites at the same contents of carbon nanoparticles, and contribution of absorption to the shielding efficiency was found to be higher than that of reflection.

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