Dual-band Mode Research Articles

New Technique for Synthesizing Concurrent Dual-Band Impedance-Matching Filtering Networks and ${\hbox{0.18-}}\mu{\hbox {m}}$ SiGe BiCMOS 25.5/37-GHz Concurrent Dual-Band Power Amplifier

New technique for synthesizing concurrent dual-band impedance-matching filtering networks is presented. The technique enables the design of concurrent dual-band impedance-matching filtering networks that provide not only simultaneous matching of two arbitrary loads to two arbitrary sources at two different frequencies, but also dual-bandpass filtering response capable of suppressing unwanted signals like the harmonics and inter-modulation products in nonlinear circuits, such as power amplifiers (PAs). A new 0.18-μm SiGe BiCMOS concurrent dual-band PA was designed based on the developed dual-band matching filtering technique around 25.5 and 37 GHz, which works in the concurrent dual-band mode (25.5 and 37 GHz), as well as single-band mode (25.5 or 37 GHz). The measured results show that, in the single-band mode, the dual-band PA exhibits gain of 21.4 and 17 dB, maximum output power of 16 and 13 dBm, and maximum power-added efficiency (PAE) of 10.6% and 4.9% at 25.5 and 37 GHz, respectively. In the dual-band mode, the maximum output power is 13 and 9.5 dBm at 25.5 and 37 GHz, respectively, and the total maximum PAE is 7.1%. The designed concurrent dual-band PA has a chip size of 1.3×0.68 mm2 and consumes a dc current of 120 mA from a 3-V supply voltage.

Dynamic deviation reduction-based concurrent dual-band digital predistortion

This article introduces the concurrent dual-band digital predistortion DPD architecture with only one upconvertion unit, which is suitable for the linearization of wideband power amplifiers PAs excited by concurrent dual-band signals. By extending the conventional dynamic deviation reduction DDR model to the concurrent dual-band mode, we propose two DDR-based concurrent dual-band models, the dual-band DDR DB-DDR model and the simplified dual-band DDR SDB-DDR model. The performance of these two models is experimentally assessed with two types of wideband PAs a GaN Class F PA and a GaN Doherty PA driven by the concurrent dual-band signal, and compared with the prior two-dimensional digital predistortion 2D-DPD model and the two-dimensional modified memory polynomial 2D-MMP model. The results prove the good DPD performance and low computational complexity of the proposed models. © 2013 Wiley Periodicals, Inc. Int J RF and Microwave CAE 24:401-411, 2014.

Concurrent dual-band envelope tracking GaN PA design and its 2D shaping function characterization

This paper presents the design of a high-power dual-band power amplifier (PA) for envelope tracking (ET) operation and its characterization in concurrent dual-band ET operation modes. The design approach relies on the specific actual signal probability distribution and the prototype was conceived for the WCDMA 3GPP DL signals. The paper discusses the impact of the ET-shaping function influence on the linearity versus mean efficiency trade-off, for both single and concurrent dual-band cases. The technique was applied to a concurrent 870 and 2140 MHz ET-PA designed around a GaN HEMT device. The ET friendly design method led to performance very close to those observed at each single band. Over a bandwidth of 100 MHz and for PAR = 6.5 dB, the measured results reported a mean DE better than 71 and 54%, with a peak power higher than 55 and 54 dBm, at the two frequency bands, respectively. When evaluated in concurrent dual-band mode with two WDCMA signals at 6.5 dB PAR each, the ET-PA exhibited an estimated average total power of 49.5 dBm with 57.1% average drain efficiency.

Dual-Band, Switched-Beam, Reconfigurable Antenna for WLAN Applications

The development of WLAN technology requires antennas with additional capabilities using simple and low-cost mechanisms. This letter presents a low-cost microstrip antenna integrated with simple p-i-n diodes as RF switches. The proposed antenna is capable of steering the beam in a dual-band mode: -19°, -59°, and 61° within the 2.45-GHz band, and 6°, -14°, and 16° within the 5.8-GHz band, which meets the IEEE 802.11a, b/g requirements. The antenna consists of three different dual-band elements, connected using an H-shaped transmission line at the radiating side. The novelty of this structure lies in the ground plane design. The H-shaped transmission line is used to integrate three different ground-plane structures.

A Dual-Band Coaxial Waveguide Mode Converter for High-Power Microwave Applications

A dual-band coaxial waveguide mode converter is investigated. In the converter, the TEM mode (Coa.TEM) and TM01 circular waveguide (Cir.TM01) mode are transformed simultaneously into TE11 coaxial waveguide (Coa.TE11) mode and TE11 circular waveguide (Cir.TE11) mode, respectively. The optimized geometrical dimensions are achieved by employing the mode coupling theory. A mode converter at 1.3 GHz and 5.0 GHz is designed, and conversion efficiencies of Coa.TEM-to-Coa.TE11 and Cir.TM01-to-Cir.TE11 are 99.88% and 99.70% at central frequency, respectively. Over the frequency ranges 1.15–1.51 GHz and 4.87–5.19 GHz, the conversion efficiency exceeds 90%. A good agreement between theoretical calculations and computer simulations is observed, demonstrating the feasibility of the dual-band mode converter.

Broadband and Dual-Band Coplanar Folded-Slot Antennas (CFSAs) [Antenna Designer's Notebook

This paper presents a unified design methodology for dual-band and broadband coplanar folded-slot antennas (CFSAs). The design is achieved by using a coplanar waveguide-fed antenna element that is asymmetric with respect to the folded slot, and by adjusting the length of the stub inside the slot. A mathematical derivation, based on a transmission-line model for the asymmetrically-fed coplanar folded-slot antenna, is used on a single-frequency coplanar folded-slot antenna to determine the condition for a second resonance. In this way, when the second resonant frequency is close to the first, broadband uniplanar antennas with ~30%, bandwidth can be designed. In addition, at the dual-band mode, a frequency ratio (f <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> /f <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> ) of the order of 2.5 or more can be obtained. The effect of the ratio of the feed-shift distance to the length of the stub on the bandwidth is an important parameter, and is shown for both the broadband and dual-band designs. The presented method and tables are simple to use, provide very accurate results, and correctly predict the resonant frequencies for the dual-band coplanar folded-slot antennas. The theoretical and simulated results were verified by measurements of fabricated prototypes. The design guidelines cover a broad range of applications in the 2.4 GHz to 5.25 GHz range, with various bands and bandwidths.

Reconfigurable tri-band H-shaped antenna with frequency selectivity feature for compact wireless communication systems

This study presents an H-shaped reconfigurable antenna for wireless applications. The antenna consists of an H-shape radiator and a CPW printed on a circuit board and a varactor diode connecting the upper and lower arms of the H-shape radiator for reconfigurability. The uniqueness of the antenna lies on the ability to select the operating mode and frequencies electronically using a varactor diode. By selecting the DC-bias voltages of 11.5, 10 and 8 V across the varactor diode, which in turn selects the corresponding varactor capacitances of 2, 4 and 6 pF, the antenna can be controlled to operate in three different modes, namely a single-band mode to cover the GSM1900, a dual-band mode at 1.88 and 2.4 GHz to cover the GSM1900 and Bluetooth/WLAN, respectively and a tri-band mode at 1.57, 1.88 and 2.4 GHz to cover the GSM1900, WLAN and GPS, respectively. Furthermore, by varying the varactor capacitance from 7 to 13 pF, the GPS and WLAN bands can be tuned by 11.44% (1.57–1.4 GHz) and 6.46% (2.4–2.25 GHz), respectively, yet keeping the 1.88-GHz band unchanged. Detailed studies on the antenna&apos;s performance are carried out to investigate the behaviour of the antenna at each resonant frequency in each operating mode.

DUAL-BAND MONOPOLE ANTENNA WITH OMEGA PARTICLES FOR WIRELESS APPLICATIONS

A new design of dual-band antenna for DCS/PCS/UMTS/ WLAN/WiMAX applications is proposed. Using two metamaterials omega-shaped structures, a good impedance matching the dual-band mode is obtained. The proposed prototype antenna is fabricated on a 1.5mm thick FR4 epoxy substrate with a relative dielectric permittivity r = 4:4 and a loss tangent tanae = 0:02. Good monopole- like radiation patterns and antenna gains over the operating bands have also been observed. Efiects of each omega particle on the antenna performance and their coupling are all examined and discussed.

A Narrow Band Dual Mode HTS Patch Filter With High Power Capability

A novel structure is presented to optimize the design of narrow band dual mode patch filters. Using this method, a narrow band dual mode high power HTS filter with center frequency 2.015 GHz, fractional bandwidth less than 0.35%, return loss greater than 20 dB, near band-edge rejection close to -45 dB, and insertion loss less than 0.2 dB has been designed and fabricated. The filter can work at a power of 11.7 W without obvious deterioration of its transmission response.

Properties of microstrip filter with elliptic-fractal pattern

We described the properties of microstrip band gap filter with elliptic-fractal pattern from 40 Hz to 20 GHz. It used the characteristic of the fractal and elliptic pattern to improve the performance of microstrip band gap filter. The center frequencies of gaps of the filter were about 5.5 and 15 GHz, and the band stop bandwidth of the filter can be increased by increasing the numbers of the cell of elliptic-fractal pattern. To verify the characteristic of dual-mode band gap filter, we simulated the above microstrip filter with the finite differential time-domain method. The simulation results were in good agreement with the experimental results.

A wide-band slot antenna design employing a fictitious short circuit concept

A wide-band slot antenna element is proposed as a building block for designing single- or multi-element wide-band or dual-band slot antennas. It is shown that a properly designed, off-centered, microstrip-fed, moderately wide slot antenna shows dual resonant behavior with similar radiation characteristics at both resonant frequencies and therefore can be used as a wide-band or dual-band element. This element shows bandwidth values up to 37%, if used in the wide-band mode. When used in the dual-band mode, frequency ratios up to 1.6 with bandwidths larger than 10% at both frequency bands can be achieved without putting any constraints on the impedance matching, cross polarization levels, or radiation patterns of the antenna. The proposed wide-band slot element can also be incorporated in a multi-element antenna topology resulting in a very wide-band antenna with a minimum number of elements. It is also shown that, by using only two of these elements in a parallel feed topology, an antenna with good radiation parameters over a 2.5:1 bandwidth ratio can be obtained.

Fabrication of an X-Band Dual Mode Bandpass Filter Using Low Cost FR4 Substrate

SUMMARY The investigation presents a low cost and low insertionloss X-band dual mode bandpass filter (BPF) based on inexpensive com-mercial FR4 substrate. The proposed filter at a central frequency f 0 of11.3GHz has high filter performance filter with a fractional bandwidth of14%, the insertion loss of −2.7dB, and two transmission zeros. The de-signed procedures are presented in this letter and the fabricated filter veri-fies the proposed designed concept. key words: dual-mode, transmission zero, ring resonator, FR4 1. Introduction Miocrowave communication systems are expanding rapidlyto higher frequency such as C-band or X-band since they canprovide many advantages over conventional wireless links,for example the larger bandwidth and smaller device size.Waveguide components are widely used at these frequenciesand offer very good performance. However, they result inhigh production costs and bulky systems. Conventional pla-nar filter structures suffer from radiation from the resonatorsinto the substrate and from high ohmic loss, and there-fore give high insertion loss and poor filter rejection. Re-cently, the micromachined techniques have been providedand shown to enhance filter performance by removing thedielectric material up to a thin membrane that suspends theplanar filters, therefore reducing of the radiation, ohmic,and dielectric losses of resonators [1],[2]. However, thereis still a challenge in cost down of the commercial RF mi-cromachined device since the devices are fabricated in thesemiconductor-like process.In this letter, we have succeeded to fabricate an lowcost and low loss X band dual mode BPF by using inex-pensive commercial FR4 GD (Glass-Epoxy Double Sided)substrates with thickness of 0.4mm and original relative di-electric constant e