Showing papers on "Coplanar waveguide published in 2013"

Analysis and Design of Stacked-FET Millimeter-Wave Power Amplifiers

Abstract: Stacked field-effect transistor (FET) CMOS millimeter-wave power amplfiers (PAs) are studied with a focus on design of appropriate complex impedances between the transistors. The stacking of multiple FETs allows increasing the supply voltage, which, in turn, allows higher output power and a broader bandwidth output matching network. Different matching techniques for the intermediate nodes are analyzed and used in two-, three-, and four-stack single-stage $Q$ -band CMOS PAs. A four-stack amplifier design achieves a saturated output power greater than 21 dBm while achieving a maximum power-added efficiency (PAE) greater than 20% from 38 to 47 GHz. The effectiveness of an inductive tuning technique is demonstrated in measurement, improving the PAE from 26% to 32% in a two-stack PA design. The input and output matching networks are designed using on-chip shielded coplanar waveguide transmission lines, as well as metal finger capacitors. The amplifiers were implemented in a 45-nm CMOS silicon-on-insulator process. Each of the amplifiers occupies an area of 600 $\mu$ m $\,\times\,$ 500 $\mu$ m including pads.

Displacement Sensor Based on Diamond-Shaped Tapered Split Ring Resonator

Abstract: Split-ring resonators (SRRs) are ideal structures for the realization of compact high-sensitivity and high-resolution sensors due to their high-quality factor resonance, compact size, and high sensitivity to changes in the constituent materials and physical dimensions. This paper presents a displacement sensor based on a diamond-shaped tapered SRR coupled to a coplanar waveguide. Two significant improvements over previous designs are reported. Firstly, the proposed sensor has higher dynamic range and linearity for displacement sensing. Secondly, compared with previous designs, where the displacement changes both the resonant frequency and depth of the transmission notch, the proposed sensor has a fixed resonant frequency. This is an important improvement since the sensor can be operated at a single fixed frequency and bypass the need for a frequency-sweeping microwave source and measurement system such as an expensive network analyzer. It is shown that, while preserving the compact size, the proposed sensor also benefits from a lower operating frequency. The design principle and simulation results are validated through measurement.

Interchip communication using a dielectric waveguide

Abstract: An apparatus is provided. There is a circuit assembly (206-A1) with a package substrate (304-A) and an integrated circuit (IC) (302-A). The package substrate has a microstrip line (208-A1), and the IC is secured to the package substrate and is electrically coupled to the microstrip line. A circuit board (202-A) is also secured to the package substrate. A dielectric waveguide (204- A) is secured to the circuit board. The dielectric waveguide has a dielectric core (310-A) that extends into a transition region (314- A) located between the dielectric waveguide and the microstrip line, and the microstrip line is configured to form a communication link with the dielectric waveguide.

Rotation Sensor Based on Horn-Shaped Split Ring Resonator

Abstract: This paper presents a rotation sensor based on a modified split ring resonator (SRR) coupled to a coplanar waveguide. It is shown that compared with previous SRR-based rotation sensors, the proposed sensor benefits from a higher dynamic range and superior linearity. It is shown that the geometry of the SRR can be optimized to compensate for the non-uniformity of the magnetic flux through the SRR, in order to suppress the unwanted frequency shift in the resonance. This is a significant improvement because the sensor can be operated as an inexpensive single frequency system. The concept and simulation results are validated by experimental measurements.

Broadband Circularly Polarized Slot Antenna Array Using Sequentially Rotated Technique for $C$ -Band Applications

Abstract: This letter presents the investigation results on a novel circularly polarized square-slot antenna (CPSSA) array designed to operate at a frequency of 5.5 GHz. In order to realize the proposed antenna array, four miniature circular polarized square-slot antennas are used with L-shape grounded strips located at the slots' opposite corners to reduce cross polarization. The antenna is fed by symmetric coplanar waveguide. The CPSSA element achieves a bandwidth of 16.6% for an axial ratio $\leq 3~$ dB. The CPSSA's performance is further enhanced with the construction of a novel 2 $\,\times\,$ 2 antenna array that is designed using sequentially rotated feed technique. The 3-dB axial ratio of the array extends to approximately 2 GHz with an impedance bandwidth of 31%. The CPSSA array was designed to operate over the frequency range between 4 and 6.825 GHz corresponding to an impedance bandwidth of 52% for ${\rm VSWR} (1.71:1). Acceptable agreement between the simulation and measured results validates the proposed design.

Triband Planar Monopole Antenna With Compact Radiator for WLAN/WiMAX Applications

Abstract: A novel coplanar waveguide (CPW)-fed triband planar monopole antenna is presented for WLAN/WiMAX applications. The monopole antenna is printed on a substrate with two rectangular corners cut off. The radiator of the antenna is very compact with an area of only 3.5 × 17 mm2, on which two inverted-L slots are etched to achieve three radiating elements so as to produce three resonant modes for triband operation. With simple structure and small size, the measured and simulated results show that the proposed antenna has 10-dB impedance bandwidths of 120 MHz (2.39-2.51 GHz), 340 MHz (3.38-3.72 GHz), and 1450 MHz (4.79-6.24 GHz) to cover all the 2.4/5.2/5.8-GHz WLAN and the 3.5/5.5-GHz WiMAX bands, and good dipole-like radiation characteristics are obtained over the operating bands.

Uniplanar polarisation diversity antenna for ultra-wideband systems

Abstract: A new compact, uniplanar, polarisation-diversity, monopole-like slot antenna for ultra-wideband (UWB) systems is presented. The proposed design effectively integrates orthogonally fed slot antennas, utilising the uniplanar nature of coplanar waveguide without degrading the time-domain characteristics and diversity performance. To achieve high isolation between the ports, a strip is integrated diagonally in the ground plane. Furthermore, by loading arc shaped slot resonators on the feeding structures, the proposed antenna successfully rejects the undesired subband, assigned for IEEE 802.11a and HIPERLAN/2. The measured results demonstrate that the antenna provides a 2:1 voltage standing wave ratio (VSWR) band from 2.76 to 10.75 GHz whereas showing rejection in the frequency band 4.75-6.12 GHz, along with an inter-port isolation better than 15 dB. The proposed radiator displays a nearly omnidirectional radiation pattern, along with a moderate gain and efficiency. The envelope correlation coefficient discloses a good diversity performance across the UWB spectrum. Furthermore, the time-domain analysis shows minimum dispersion to the radiated pulse. In addition, the experimental analysis indicates that the proposed design is less disposed to the housing effects when mounted in metallic casing. All these features make the proposed antenna a viable candidate for UWB dual-polarised multiple-input-multiple-output applications.

Quantum state characterization of a fast tunable superconducting resonator

Abstract: We demonstrate a frequency-tunable superconducting coplanar waveguide resonator, with a tuning range of half a gigahertz and a switching time of 1 ns. The resonator is made tunable by inserting a superconducting quantum interference device in the center strip of the resonator. Quantum measurements are made by probing the resonator with a superconducting qubit, allowing us to use microwave photon Fock states to benchmark the resonator performance. Using the resonator, we shuttle energy quanta between the qubit and a microscopic two-level state. The tunable resonator can, therefore, serve as a communication bus or memory element in a prototype quantum processor.

Superconducting coplanar waveguide resonators for low temperature pulsed electron spin resonance spectroscopy

Abstract: We discuss the design and implementation of thin film superconducting coplanar waveguide micro-resonators for pulsed electron spin resonance experiments. The performance of the resonators with P doped Si epilayer samples is compared to waveguide resonators under equivalent conditions. The high achievable filling factor even for small sized samples and the relatively high Q-factor result in a sensitivity of 4.5 × 108 spins per shot, which is superior to that of conventional waveguide resonators, in particular to spins close to the sample surface. The peak microwave power is on the order of a few milliwatts, which is compatible with measurements at ultra-low temperatures. We also discuss the effect of the nonuniform microwave magnetic field on the Hahn echo power dependence.

Broadband CPW Feed for Millimeter-Wave SIW-Based Antipodal Linearly Tapered Slot Antennas

Abstract: To achieve broadband performances in the millimeter-wave range, antipodal linearly tapered slot antenna (ALTSA) designs with new combined substrate integrated waveguide (SIW) and regular coplanar waveguide (CPW) feeds are presented and studied. This feed structure eliminates the fabrication of air bridges in direct CPW-fed tapered slot antennas (TSAs). Two millimeter-wave design techniques are introduced for the selected 41–61 GHz and 90–120 GHz frequency ranges, demonstrating very good impedance match and nearly constant gain, beamwidth, and cross-polarization levels over bandwidths of 39% and 28%, respectively. The design procedure is validated by comparing simulated results with measurements performed on a 21–31 GHz (38% bandwidth) prototype. Very good agreement between measured and calculated performance characteristics is obtained with only cross-polarization levels slightly higher than predicted. The structural design parameters and dimensions of all three designs are given.

A CPW-Fed Dual Band-Notched UWB Antenna with a Pair of Bended Dual-L-Shape Parasitic Branches

Abstract: In this paper, a novel coplanar waveguide (CPW) fed dual band-notched ultra-wideband (UWB) antenna with circular slotted ground is proposed. In order to achieve two notched bands at 3.3{3.7GHz for worldwide interoperability for microwave access (WiMAX) and 5.15{5.825GHz for wireless local area network (WLAN) respectively, a pair of bended dual- L-shape branches are attached to the slotted ground. By optimizing the lengths and positions of the branches, the desired notch-bands of WLAN and WiMAX can be achieved. The prototype of the proposed antenna was fabricated and tested. The simulated and measured results show good agreement over the ultra-wideband. Besides these mechanical features, such as compact in size, easy in fabrication, the proposed antenna also shows good characteristics in its radiation patterns and time-domain behaviors. So it is a nice candidate for modern UWB communication systems.

Through-glass copper via using the glass reflow and seedless electroplating processes for wafer-level RF MEMS packaging

Abstract: We present a novel method for the fabrication of void-free copper-filled through-glass-vias (TGVs), and their application to the wafer-level radio frequency microelectromechanical systems (RF MEMS) packaging scheme. By using the glass reflow process with a patterned silicon mold, a vertical TGV with smooth sidewall and fine pitch could be achieved. Bottom-up void-free filling of the TGV is successfully demonstrated through the seedless copper electroplating process. In addition, the proposed process allows wafer-level packaging with glass cap encapsulation using the anodic bonding process, since the reflowed glass interposer is only formed in the device area surrounded with silicon substrate. A simple coplanar waveguide (CPW) line was employed as the packaged device to evaluate the electrical characteristics and thermo-mechanical reliability of the proposed packaging structure. The fabricated packaging structure showed a low insertion loss of 0.116 dB and a high return loss of 35.537 dB at 20 GHz, which were measured through the whole electrical path, including the CPW line, TGVs and contact pads. An insertion loss lower than 0.1 dB and a return loss higher than 30 dB could be achieved at frequencies of up to 15 GHz, and the resistance of the single copper via was measured to be 36 mΩ. Furthermore, the thermo-mechanical reliability of the proposed packaging structure was also verified through thermal shock and pressure cooker test.

A Lossy Circuit Model Based on Physical Interpretation for Integrated Shielded Slow-Wave CMOS Coplanar Waveguide Structures

Abstract: This paper presents a new physical model for shielded slow-wave coplanar waveguide structures. This lossy electrical model is based on physical behavior of the transmission lines. It allows a better understanding of the losses distribution along the structure. The ohmic losses in the coplanar strips, as well as the ohmic losses and the eddy current losses in the floating shield strips are studied for transmission lines having different geometrical dimensions and hence electrical characteristics. The model is then validated on different CMOS technologies and leads to the efficient optimization of the slow-wave transmission lines, especially concerning the floating shield dimensions.

A New Low Cost Leaky Wave Coplanar Waveguide Continuous Transverse Stub Antenna Array Using Metamaterial-Based Phase Shifters for Beam Steering

Abstract: In this paper, we have proposed a new leaky-wave coplanar waveguide (CPW) continuous transverse stub (CTS) antenna array with metamaterial-based phase shifters for beam steering applications. The array integrates three CTS elements and two 6-stage negative reflective index (NRI) phase shifters, and is fed by CPW transmission line. Beam steering capabilities are achieved by tuning the values of the NRI phase shifters. The proposed CPW-CTS array is fabricated for 2.4-GHz wireless local area network (WLAN). The measured data, including parameters, radiation patterns and gain, agree well with the simulation results. A scan-angle range from 58 to 124 of unidirectional radiation pattern is measured in the -plane with good impedance matching (-1 dB ). Designs incorporating continuous beam steering using tunable NRI metamaterial phase shifters are also discussed.

Epsilon Negative Zeroth- and First-Order Resonant Antennas With Extended Bandwidth and High Efficiency

Abstract: This paper presents a new method to extend the bandwidth of metamaterial (MTM) antennas using an epsilon negative transmission line (ENG-TL). The bandwidth characteristics of zeroth-order resonance (ZOR) and first-order resonance (FOR) are analyzed and described using circuit parameters based on the ENG-TL theory. An equivalent circuit model for the FOR is derived to understand its working principle. The asymmetric coplanar waveguide (ACPW) adopted as the host TL not only offers high freedom to implement the circuit elements, but also overcomes the design constraint of the traditional CPW. Based on the proposed bandwidth extension technique, dual-band and wideband MTM antennas are designed. They provide size reduction, extended bandwidth and high efficiency, which are good candidates for modern wireless communication systems (GSM, UMTS, LTE, WLAN, WiMAX).

Shielding of the electromagnetic field of a coplanar waveguide by a metal film: Implications for broadband ferromagnetic resonance measurements

Abstract: We show that the propagation of microwave fields along a planar transmission line is strongly modified when a conducting film is brought close to it. The effect is attributed to the shielding of the electrical and/or magnetic microwave fields which is shown to occur over a wide range of parameters (microwave frequency, film square resistance, transverse dimensions of the waveguide). This is illustrated by finite-element electromagnetic simulations and interpreted using a distributed impedance model. We discuss the implications of this phenomenon for broadband measurements of ferromagnetic resonance realized by placing a ferromagnetic metal film above a coplanar waveguide.

Feasibility Study of Optically Transparent CPW-Fed Monopole Antenna at 60-GHz ISM Bands

Abstract: This paper presents a feasibility study on an optically transparent planar monopole lozenge antenna at the 60-GHz industrial-scientific-medical (ISM) band. The feeding of this antenna is composed of a 50- $\Omega$ meshed coplanar waveguide. The size of the proposed antenna is around 2.3 $\,\times\,$ 2.3 mm $^{2}$ . The transparent and conductive material used to fabricate the proposed antenna is made of a gold grid layer deposited on a 0.2-mm-thick fused silica 7980 Corning substrate. The theoretical transparency equals 83% with a sheet resistance of 0.44 $\Omega$ /sq. The simulated and measured results of the transparent monopole antenna are compared to a nontransparent (but identical) antenna. It was found that both antennas have the same performances in terms of bandwidth, radiation pattern, and gain. The measurements show the same behavior for transparent and nontransparent antennas. These results confirm the absence of ohmic and skin depth losses in the gold grid layer at 60-GHz ISM bands and provide the possibility of implementing transparent antennas with performances absolutely identical to the nontransparent ones, with the advantage of a soft visual impact.

Design of Chipless UWB RFID System Using A CPW Multi-Resonator

Abstract: In this paper, the design of a novel chipless ultra-wideband radio-frequency identification (UWB RFID) system is proposed. The system employs printable uniplanar chipless tags and a pair of high-gain reader antennas. The chipless tag is composed of two UWB monopole antennas, connected by a coplanar waveguide (CPW). The tag's ID is represented by a spectral signature in the UWB frequency range, and is created by a multi-resonator embedded on the coplanar waveguide. The detection of the tag's ID is based on using only the amplitude of the spectral signature, which significantly simplifies the complexity of detection. The reader employs two separate Vivaldi antennas - one for transmitting a vertically polarized signal, and the other for receiving a horizontally polarized signal - to reduce the mutual coupling between the uplink and downlink signals. Further reduction of mutual coupling is achieved by using a copper plate at the reader to separate the uplink and downlink signals. These two proposed methods together reduced the mutual coupling by 20 dB. The chipless RFID tag with eight coplanar waveguide resonators in a group and the reader antennas were designed using computer simulation, and fabricated on Rogers substrates for measurement. The results of studies in an anechoic chamber showed that the proposed UWB RFID system could achieve a reading range of larger than 30 cm, at least three times longer than the maximum distance of a similar system reported by others. This indicated that the proposed system has great potential for short-range item tracking at low cost.

DC and RF Measurements of Serial Bi-SQUID Arrays

Abstract: SQUID arrays are promising candidates for low-profile antennas and low-noise amplifier applications. We present the integrated circuit designs and results of dc and radio frequency measurements of wideband serial arrays based on the integration of linear bi-SQUID cells forming a superconducting quantum interference filter (bi-SQUID SQIF). Various configurations of serial array designs are described. The measured linearity, power gain, and noise temperature are analyzed and compared. The experimental results are matched to results of mathematical modeling. A serial bi-SQUID SQIF arrays are integrated into a coplanar waveguide, and symmetrically grounded to corresponding sides of the coplanar waveguide. The radio frequency output comes out from the central common line, which is also used for dc biasing, and forms a symmetrical balanced output. The signal and dc flux biasing line is designed as coplanar lines passed in parallel over each bi-SQUID cell in a bidirectional fashion concentrating magnetic flux inside of each cell. Serial bi-SQUID SQIF arrays are fabricated on 5 mm × 5 mm chips using a standard HYPRES niobium 4.5 kA/cm2 fabrication process.

Low-Cost CPW Meander Inductors Utilizing Ink-Jet Printing on Flexible Substrate for High-Frequency Applications

Abstract: This paper describes the design and fabrication of low-cost coplanar waveguide (CPW) miniature meander inductors. Inductors are fabricated on a flexible plastic polyimide foil in ink-jet printed technology with silver nanoparticle ink in a single layer. For the first time, the detailed characterization and simulation of CPW inductors in this technology is reported. The inductors are developed with impressive measured self-resonance frequency up to 18.6 GHz. The 2.107-nH inductor measures only 1 mm × 1.7 mm × 0.075 mm and demonstrates a high level of miniaturization in ink-jet printing technology. The measured response characteristics are in excellent agreement with the predicted simulation response.

Design of a Coplanar Sensor for RF Characterization of Thin Dielectric Samples

Abstract: A multilayered conductor backed coplanar waveguide (MCCPW) sensor for the non-destructive characterization of thin dielectric samples in the RF and microwave frequency band is designed and developed. The newly designed sensor allows the measurement of complex permittivity of thin dielectric samples over a wide frequency band in a non-destructive way as it does not require any special sample preparation except for the fact that the surface of the test sample should be flat for good contact with the coplanar waveguide. The overall procedure is based on the measurement of scattering parameters of the test specimen placed at the top of the designed coplanar sensor in the specified frequency band using the vector network analyzer. The measured scattering data are then employed to compute the effective permittivity of the coplanar (MCCPW) structure using the revised form of the reflection-transmission approach. From the practical point of view, the advantage of the proposed technique is that it employs only two SMA to coplanar end launchers in lieu of the expensive microwave probe stations commonly being used in the past for carrying out such kinds of measurements. The applicability of the designed sensor is tested by extracting the permittivity of a number of reference samples from both the simulated and the experimental data.

A Printed LPDA Fed by a Coplanar Waveguide for Broadband Applications

Abstract: A printed log-periodic dipole array (LPDA), operating between 3 and 6 GHz and fed with a coplanar waveguide, is presented. The antenna has been designed starting from Carrel's theory, optimized using CST Microwave Studio 2012, and then realized. The comparison between simulated and measured results shows that the proposed antenna can be used for broadband applications in the whole operating frequency band (3-6 GHz), with a very good input matching and a satisfactory endfire radiation pattern.

Periodic Leaky-Wave Antenna on Planar Goubau Line at Millimeter-Wave Frequencies

Abstract: A periodic leaky-wave antenna on a planar Goubau line is presented. This transmission line is formed by a planar single-wire waveguide on a thin dielectric substrate. Leakage is produced by adding dipoles along the line on the bottom face of the substrate. A coplanar waveguide is used to feed the antenna, which acts as a smooth transition between the input coaxial cable and the planar Goubau line. The advantage of using this line lies on its losses, lower than those of typical microstrip lines due to the absence of a ground plane. As a result, a higher radiation efficiency than in microstrip-fed antennas can be obtained while keeping similar advantages, e.g., low profile or low production cost. A prototype of the antenna at 40 GHz has been fabricated. Measurements of this prototype are presented in this letter.

A Planar Transmission-Line Sensor for Measuring the Microwave Permittivity of Liquid and Semisolid Biological Materials

Abstract: A planar transmission-line configuration for rapid, nondestructive, wideband permittivity measurements of liquid and semisolid materials at microwave frequencies is described. The transmission-line propagation constant of the proposed configuration is determined with the multiline technique from scattering parameter measurements of two lines with a known length difference. Guidelines for the appropriate selection of the line dimensions and a technique for resolving the phase ambiguity associated with the multiline technique are presented. The material permittivity is related to the propagation constant by closed-form expressions that allow the permittivity to be determined by a relatively simple numerical inversion procedure. The proposed sensor has the advantage of not requiring the sample to have uniform edges, nor that they are perpendicular to the planar line. The technique used for determining the line propagation constant has the advantage of not requiring any transmission-line discontinuities to be explicitly modeled. To illustrate the technique, a coplanar waveguide transmission-line sensor was fabricated and used to measure the permittivity of six liquids and four gelatin samples from 1 to 5 GHz. These measurements agree very well with coaxial-line probe measurements, demonstrating the accuracy of the proposed configuration. The sensitivity of the results to dimensional tolerances is demonstrated.

Compact Topside Millimeter-Wave Waveguide-to-Microstrip Transitions

Abstract: This letter presents two different waveguide-to-microstrip transition designs for the 76-81 GHz frequency band. Both transitions are fabricated on a grounded single layer substrate using a standard printed circuit board (PCB) fabrication process. A coplanar patch antenna and a feed technique at the non-radiating edge are used for the impedance transformation. In the first design, a conventional WR-10 waveguide is connected. In the second design, a WR-10 waveguide flange with an additional inductive waveguide iris is employed to improve the bandwidth. Both designs were developed for the integration of multi-channel array systems allowing an element spacing of λ0/2 or less. Measurement results of the first transition without the iris show a bandwidth of 8.5 GHz (11%) for 10 dB return loss and a minimum insertion loss (IL) of 0.35 dB. The transition using the iris increases the bandwidth to 12 GHz (15%) for 10 dB return loss and shows a minimum insertion loss of 0.6 dB at 77 GHz.

The development and evaluation of RF TSV for 3D IPD applications

Abstract: In this paper, Silex Microsystems, the world's largest Pure-Play MEMS foundry, together with partners TNO and VTT, present our recent advancements in RF through silicon Vias (TSV) for 3D integrated passive devices (IPD) applications, achieved in conjunction with the European consortium EPAMO. A novel open TSV fabrication process on 200 mm diameter 305 μm thick High Resistivity wafers has been used to demonstrated High Aspect Ratio Through Silicon Vias (HAR TSV), focusing on tight pitch, resulting in 36 TSV/mm2 Via density. 305 μm wafer thickness enables the fabrication of rigid interposers, an advancement in the commercialization of 3D packaging technology. The fabrication includes double sided deep reactive ion etching (DRIE), developments and evaluation on various conformal high aspect ratio (HAR) plating seedlayer processes, and void-free TSV Cu plating of open rigid TSV structures and bonding to glass wafers for characterization. The electrical characterization of the fabricated devices was performed by VTT with excellent measured RF properties: in specific, low RF losses as well as low DC resistances of less than 20 mOhm/TSV. Several different coplanar waveguide (CPW) test vehicles and other RF TSV test structures together with Daisy Chain and parasitic Capacitance test structures were designed, fabricated and evaluated. The loss of a single coplanar TSV transition is less than 0.04 dB @ 5 GHz, which is considered to be very small. The developed TSV technology was also employed to fabricate 3D toroidal inductors. These inductors were characterized by TNO showing high Q-factor (>30) and self-resonance frequency (> 6 GHz) for 3D inductors in the range of 1-15 nH. 1 and 2 port inductor temperature characteristics over temperature interval from room temperature to 111°C are reported. A fabrication integration scheme for fully integrated RF-IPD with 3D TSV based inductors and high ohmic polysilicon (p-Si) resistors and piezoelectric (PZT) metal-insulator-metal (MIM) capacitors are discussed. Outlook for improvements using integrated high frequency magnetic flux materials and commercialization aspects are described.

Dielectric Permittivity of Porous Si for Use as Substrate Material in Si-Integrated RF Devices

Abstract: Dielectric permittivity of porous Si (PSi) layers formed on a low-resistivity p-type Si (0.001-0.005 Ω.cm) is thoroughly investigated using analytical expressions within the frame of broadband transmission line characterization method in the frequency range 1-40 GHz. It is demonstrated that the value of Si resistivity is critical for the resulting PSi layer permittivity even within the above limited resistivity range. The real part of PSi dielectric permittivity changes monotonically between 1.8 and 4 by changing the Si resistivity between 0.001 and 0.005 Ω.cm. The above study was made for porosities between 70% and 84%. The quality factor and attenuation loss of the investigated coplanar waveguide transmission lines were found to be Q=26 and a=0.19ndB/mm, respectively, at 40 GHz. These values are competitive to those obtained on quartz, which is one of the off-chip RF substrates with the lowest losses. This confirms the superiority of the PSi material, mentioned above, for use as a local substrate for the on-chip RF device integration.

Bandwidth Enhancement of Asymmetric Coplanar Waveguide (ACPW)-Fed Antenna Based on Composite Right/Left-Handed Transmission Line

Abstract: A novel wideband antenna based on composite right/left-handed transmission line (CRLH-TL) is presented. The bandwidth enhancement of the antenna can be achieved when the zeroth-order and first-positive-order modes are closely spaced and merged together. The uniplanar asymmetric coplanar waveguide (ACPW) is adopted as the host transmission line. The ACPW structure not only offers the design freedom to implement the circuit parameters, but also overcomes the design constraint of the traditional CPW. The measured results show that the operating bandwidth is 1720 MHz (2.1–3.82 GHz), corresponding to approximately 58.1% fractional bandwidth. Owing to the characteristics of wide bandwidth, enhanced efficiency, and omnidirectional radiation, the proposed antenna is a good candidate for modern wireless communication systems (LTE, WLAN, WiMAX).

Compact tri-band CPW-fed antenna for WLAN/WiMAX applications

Abstract: A compact triple-band coplanar waveguide (CPW)-fed antenna for WLAN/WiMAX applications is proposed. The radiation patch is fed by capacitive coupling of the top transmission line. By only using one metallic strip etched on the bottom of the substrate, tri-band resonances of the antenna are generated. The proposed antenna has a compact size of 30 × 27 mm2, which can provide stable omnidirectional radiation patterns in three bands. The measured − 10 dB impedance bandwidths are 150 MHz (2.39–2.54 GHz), 360 MHz (3.37–3.73 GHz) and 1170 MHz (5.02–6.19 GHz), which is suitable for WLAN/WiMAX applications.