Good Gain Flatness Research Articles

Broadband high‐efficiency high‐gain dual‐beam empty substrate integrated waveguide cavity‐backed filtenna

AbstractA broadband high‐efficiency high‐gain empty substrate integrated waveguide cavity‐backed filtenna with dual beams is proposed. The antenna is vertically stacked by three cavities. Two rectangular slots are etched above the uppermost cavity to realize the radiation function. Since the interior of the cavity is covered with metal, the characteristics of the antenna are independent of the used dielectric substrate. The fractional bandwidth of the proposed filtenna is 21.1%, and the efficiency can reach more than 90% in the operational band. The antenna has good frequency selection properties, and the ratio of the −10 dB impedance bandwidth to the −3 dB impedance bandwidth is 0.88. Good gain flatness is obtained, the maximum gain of the filtenna within the operational band is 8 dBi. The proposed dual‐beam filtenna can realize broadband and filtering simultaneously, with low cost and high efficiency. It can be used in wireless communication systems.

Design of High-isolation Miniaturized Multi-channel Ku-band Driving Module

The driving module is the key component of the electronic scanning array radar system, which controls the radio frequency signal of the whole radar. It must have the characteristics of high performance, low cost, lightweight, miniaturization and easy to use. To meet this requirement, a miniaturized multi-channel Ku-band driving module design scheme is proposed in this paper. The module integrates four-channel T/R amplifier circuits, two-channel calibration switch circuits, and a RF power division network, with a total of 19 radio frequency interfaces, which can significantly reduce the number of active amplifiers in the radar system. The module adopts a positive and negative double-sided open-cavity design, combines with vertical interconnection technology to achieve more than 80dBc channel isolation of calibration switch circuit, and has good gain flatness and inter-channel phase consistency. The overall size of the module is 107mm*84mm*12mm, the weight is only 202g, the transmit power of the odd channel is greater than 26.7dBm, and the transmit power of the even channel is greater than 28.4dBm. This module can be widely used in car navigation, radar detection, and other fields due to its characteristics of small size, rich function, and easy integration.

D-Shaped Fiber Bragg Grating Ultrasonic Hydrophone With Enhanced Sensitivity and Bandwidth

In this paper, we demonstrate a miniature flexible FBG-based underwater ultrasonic sensor with enhanced pressure sensitivity and bandwidth using a side-polished configuration of ∼54 μ m depth and ∼15 mm length. The opto-mechanical responses of the sensor to acoustic-induced strain in axial and radial receiving modes are investigated and characterize the gain sensitivity dependent on the wavelength/Bragg length ratio. Then, ultrasonic testing in a water tank exhibited a maximum radial acoustic pressure-induced wavelength shift of 91.29 nm/MPa and a noise equivalent acoustic signal level of ∼49.6 mPa/Hz1/2 in the range of 40–120 kHz, as well as a good gain flatness of less than 9.4 dB. This is significantly superior to FBG-based hydrophones previously ever reported to our knowledge. The proposed technique greatly simplifies the miniaturized integration of all-optical ultrasonic detectors and could, therefore, be further improved for ultra-high sensitive hydrophones in optoacoustic imaging.

Implementation of Flat Gain Broadband Power Amplifier With Impedance Rotation Compensation

The conventional broadband impedance matching network in low-pass structure cannot present adequate broadband impedance rotation for the optimum broadband operation of the power amplifier (PA), resulting in performance variations and degradations. The underlying constraint is the phenomenon of opposite impedance rotation. Against such a backdrop, this paper presents a methodology using the band-pass topology to compensate the frequency-variable response of the PA. The CGH40010F from Cree is used to verify the effectiveness of this compensation method. The experimental results are in good agreement with the simulation. The proposed PA yields good gain flatness (±0.5 dB), input/output return loss (>13 dB), and high power added efficiency (>60 %) over the band from 1.7 to 2.7 GHz. After digital predistortion, the measured adjacent channel power ratio is about −55 and −50 dBc at ±5 and ±10 MHz offset when the PA is driven by 5- and 10-MHz WCDMA signals at 6.5 ~ 7 dB power back-off.

A New Wide-band Low-voltage Low-noise Amplifier with Gain Boosted and Noise Optimized Techniques

This work develops a new CMOS wide-band low-voltage low-noise amplifier (LNA). The proposed LNA uses negative feedback and gain boosted technique to increase its high-frequency gain to achieve high gain and wide bandwidth simultaneously. The proposed LNA uses mirror bias technique to achieve full output swing, and its operating current does not change due to changes in the supply voltage. The two-stage structure can improve the gain flatness, high gain, and low noise figure. Therefore, the developed LNA provides high gain, low noise, wide bandwidth, and good gain flatness performance. The operating bandwidth of the proposed LNA is between 1.5 and 3.5 GHz. The measured gain of the LNA is higher than 15 dB, the measured input third-order intercept points (IIP3) is –7 dBm, the noise figure of the proposed LNA is less than 4.2 dB, and the power dissipations of the LNA is 8 mW at 1 V supply voltage. The proposed LNA is implemented in a Taiwan Semiconductor Manufacturing Company 0.18-μm RF CMOS process. The chip area is 0.28 mm2.

A bandwidth-enhanced planar endfire antenna based on surface waves

ABSTRACTA surface-wave-based endfire antenna with an enhanced impedance bandwidth is presented in this paper. The antenna consists of a surface-wave guide (SWG) and five strips printed on the SWG. The endfire radiation benefits from the surface-wave diffraction of the SWG which is investigated with the Snell's law, effective surface impedance and eigenvalue analysis. A prototype is fabricated and measured, and the measured results indicate that the antenna has two resonances and its bandwidth is enhanced up to 16.1% (4.0–4.73 GHz). The proposed endfire antenna also exhibits high gain, good gain flatness, low cross-polarization level and low profile.

Design Approach for Implementation of Class-J Broadband Power Amplifiers Using Synthesized Band-Pass and Low-Pass Matching Topology

A new synthesis method for the design of broadband impedance matching network has been introduced to match the transistor input. The proposed matching network would be a realistic alternative to those that are frequently designed in low-pass structure. Easy-to-use design equations are given for this filter-based matching network. The required impedance of the stubs and the connecting lines can be directly calculated from the equations. This synthesis method simplifies the implementation of the network in the distributed form as compared with the LC low-pass matching network where equivalences are necessarily required in the rough conversion from lumped-to-distributed elements. The high-efficiency mode of operation is guaranteed by the constructed output low-pass matching network, since the LC low-pass network can provide the prescribed load terminations at fundamental frequencies and at harmonics. A commercially available 10-W GaN HEMT device (CGH40010) was used in this investigation. The proposed broadband power amplifier exhibits band-pass Chebyshev response in S-parameter measurements, and yields good gain flatness (±0.5 dB) and input return loss (>13 dB). Power-added efficiency of 58%-72% has been measured in large-signal measurements. After digital predistortion, the measured adjacent channel leakage power ratio is below -50 dBc at ±5- and ±10-MHz offset, when driven by 5- and 10-MHz WCDMA signals at 7-dB power back off.

A 60-GHz CMOS Broadband Receiver With Digital Calibration, 20-to-75-dB Gain, and 5-dB Noise Figure

We present a 60-GHz broadband heterodyne receiver with digital calibration. In the LNA, the low-coupling coefficient transformer-based matching network and the tail switch technique are used to achieve broadband operation and increase the gain tuning range with well-defined gain steps, respectively. In the down-conversion mixer, the inductive peaking technique is employed to extend its bandwidth. In the demodulator, inverter-based $g_{m}$ stages are used to improve its gain and linearity performance. The receiver gain tuning and the I/Q mismatch calibration are achieved by utilizing digital gain control and phase tuning schemes. The measurement shows that the receiver achieves a 20-to-75-dB conversion gain, a 5-dB noise figure (NF), and a good gain flatness performance within the complete 60-GHz band (i.e., 57–66 GHz). Measured with a 60-GHz transmitter, the error vector magnitude (EVM) is better than 10% (−20 dB) in each single channel. Fabricated in a 65-nm CMOS, the receiver occupies a silicon area of 1.9 mm $\times$ 0.7 mm (including all pads) and consumes 102.4-mW dc power.

Design of a new compact planar wide band dipole antenna

AbstractA new planar compact wideband dipole antenna is presented. The proposed antenna radiation pattern is omnidirectional and very stable in the operation bandwidth with good gain flatness and low cross polarization. Three cases of the proposed antenna are simulated by linear scaling of the designed antenna which proves the design flexibility. Finally, one case of the designed antenna is fabricated and measured. This antenna which works between 1.265 GHz to 3.98 GHz has very compact dimensions 82.4 mm × 45.5 mm (0.35l1 × 0.169l1, l1 is the wavelength in the start of bandwidth), stable radiation patterns and low cross polarization. These good specifications prove the antenna design capability and ability for wideband communication system applications.

A comparative Analysis of Nonresonant Microstrip Patch-Fed Dielectric Resonator Antenna and Proximity-Fed Annular Slot Antenna

paper shows the comparative analysis of a cylindrical dielectric resonator antenna (CDRA) fed by nonresonant microstrip patch and a proximity-fed planar annular slot (PPAS) antenna. The antenna array having an antenna element for higher directive gain at the center frequency 9.04 GHz. The band-notch is detained by almost a half-wavelength split-ring parasitic element printed around the radiating patch which is excited via a proximity-fed strip line with a planning of EBG via holes. The voltage standing wave ratio (VSWR) of the annular slot antenna is less than 2.0 in the frequency band of 7.92 GHz i.e. from 2.82 to 10.74 GHz. The PPAS antenna provides good gain flatness, high efficiency and omnidirectional field pattern over its whole frequency band and is appropriate for UWB applications. While CDRA array offer a bandwidth of 3.8 GHz and maximum gain of 14.8 dBi at the operating frequency Keywordsgain, cylindrical DRA (CDRA), dielectric resonator antenna (DRA), nonresonant microstrip patch.

Reconfigurable Modal Gain Control of a Few-Mode EDFA Supporting Six Spatial Modes

We experimentally demonstrate an inline few-mode erbium doped fiber amplifier supporting six spatial modes with reconfigurable differential gain control and excellent gain flatness obtained through mode-selective bidirectional pumping of a custom fiber with a radially profiled erbium dopant distribution. A signal gain of >20 dB was obtained for all the guided modes with a differential modal gain <;2 dB and good gain flatness across the C-band.

A MULTI-BAND LOW NOISE AMPLIFIER WITH GAIN FLATNESS AND BANDWIDTH ENHANCEMENT

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.

A novel printed monopole antenna for future ultra-wideband communication systems

In this letter, a novel microstrip line-fed printed monopole antenna for ultra-wideband (UWB) short-range wireless communications is proposed. The proposed antenna consists of a trapezoidal-shaped patch with two elliptical-shaped cuts from its edge forming a bell-shaped cut. Experimental results shows that the designed antenna operates over impedance bandwidth 3.2–11.4 GHz for return loss S11 < −10 dB, which almost covering the UWB frequency bandwidth. Moreover, the antenna has a good omnidirectional radiation patterns in the H-plane with good gain flatness over the frequency range of interest. The antenna transmission characteristics at different receiving angles are also measured. By embedding a simple narrow U-shaped slot in the radiating microstrip patch, a notch in the frequency band of 5.0–6.0 GHz is obtained. The proposed antenna is considered a good candidate for UWB short-range wireless communication systems avoiding the interference of the existing wireless systems. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26113

Compact and Broadband Antenna for LTE and Public Safety Applications

The antenna presented in this letter employs a stepped T-shape structure in combination with patch tapering and a capacitive feeding mechanism to obtain broad bandwidth (BW). This antenna is specifically designed to operate for US Public Safety (PS) and Long Term Evolution (LTE) wireless communication bands covering 426-861 MHz (68% BW). The radiation pattern over this broad bandwidth remains almost unchanged with good gain flatness. The antenna has a compact three-dimensional structure with lateral dimensions being ~ 0.25 λ in length and height being ~ 0.01 λ at the lowest frequency of operation. The measured and simulated impedance and radiation characteristics results agree well, demonstrating the good performance of the broadband and compact antenna presented in this letter.

X 대역 타일형 능동 송수신 모듈 설계

A tile type active T/R(Transmit/Receive) module for X-band active array radar is demonstrated in this paper. Proposed tile type structure based on fuzz button solderless vertical interconnection shows wide band characteristic of about 30 % bandwidth in X-band with insertion loss of below 0.6 dB and input and output VSWR of less than 1.7. Moreover, the mismatching generally appeared in the vertical interconnection which shown wide band characteristic can also be minimized and, therefore, good gain flatness can be achieved.

A new CMOS wideband low noise amplifier with gain control

In this paper, a new CMOS wideband low noise amplifier (LNA) is proposed that is operated within a range of 470 MHz–3 GHz with current reuse, mirror bias and a source inductive degeneration technique. A two-stage topology is adopted to implement the LNA based on the TSMC 0.18-μm RF CMOS process. Traditional wideband LNAs suffer from a fundamental trade-off in noise figure (NF), gain and source impedance matching. Therefore, we propose a new LNA which obtains good NF and gain flatness performance by integrating two kinds of wideband matching techniques and a two-stage topology. The new LNA can also achieve a tunable gain at different power consumption conditions. The measurement results at the maximum power consumption mode show that the gain is between 11.3 and 13.6 dB, the NF is less than 2.5 dB, and the third-order intercept point (IIP3) is about −3.5 dBm. The LNA consumes maximum power at about 27 mW with a 1.8 V power supply. The core area is 0.55×0.95 mm 2.

Two new ultra‐wideband antennas with 3.4/5.5 GHz dual band‐notched characteristics

AbstractThis letter presents two ultra‐wideband (UWB) antennas with 3.4/5.5 GHz dual‐notched bands. The U‐ and V‐slots are used to reject the frequency band (3.3–4.2 GHz) limited by C‐band satellite communication and Wimax systems. Another rejection band (5.15–5.825 GHz), limited by IEEE 802.11b or HIPERLAN/2 system, is obtained by using the U/V‐slot defected ground structure. Experimental results indicate that these antennas cover the entire UWB for voltage standing wave radio &lt;2, except two notched bands. Moreover, these antennas have omnidirectional radiation patterns in the H‐plane and good gain flatness. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 2942–2945, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24792

High-Spectral-Purity Millimeter-Wave Signal Optical Generation

In this paper, novel approaches for millimeter-wave signal generation using double-sideband suppressed-carrier modulation and four-wave mixing are proposed and demonstrated. The millimeter-wave signal is generated at a photodetector by beating the optical sidebands, which are gained from intensity modulation and after semiconductor optical amplifiers. In the proposed methods, the generated millimeter-wave signal has a frequency that is double, quadruple, sextuple, 12 times, or even 18 times higher than the microwave drive signal. And, it has quite good gain flatness with extremely high-spectral-purity and stability. The phase noise performance of the generated millimeter wave is investigated. The 3-dB linewidth of the millimeter wave has no broadening after propagating through 20-km standard single-mode fiber.

Miniaturization of an Ultra-Wideband Antenna with Two Spiral Elements

In this letter, novel antennas with two spiral elements are presented for ultra-wideband application. The original antenna consists of a T-shaped microstrip feed line, two spiral radiating elements, and a ground plane with two circular slots. It measures 30 mm 40 mm 1.6 mm. Spiral elements are used to increase the lower bandwidth limit. To further reduce the size of the antenna, the original antenna is cut in half by using the symmetry of the surface current distributions. The proposed antennas feature omnidirectional radiation patterns and good gain flatness.

A CPW-Fed Diamond Monopole Antenna with Dual Stopband Characteristic for UWB Communications

A coplanar waveguide (CPW) fed diamond monopole antenna with dual stopband characteristic is presented in this paper. The proposed antenna consists of a circular CPW feeding line and a diamond shape radiation patch. By using a U-slot in the feeding line, a stopband of 800 MHz for band rejection of wireless local area network (WLAN) is achieved. Another stopband of 600 MHz is obtained by implanting two slits in the ground plane. Experimental results show the designed antenna, with a compact size of 40 mm × 25.8 mm, has an impedance bandwidth of 3.2–10.7 GHz for voltage standing wave radio (VSWR) less than 2, except two frequency stopbands of 3.4–4.3 GHz and 5.1–5.9 GHz. Moreover, the antenna also shows omnidirectional radiation patterns in the H-lane and good gain flatness.