Showing papers on "Balun published in 2018"
TL;DR: In this article, a broadband dual-polarized filtering dipole antenna for base station application is presented, which consists of four parts: main radiator, feeding baluns, reflector, and two parasitic loops.
Abstract: This paper presents a broadband dual-polarized filtering dipole antenna for base-station application, which has a compact size of 50 $\text {mm} \times 50\,\,\text {mm} \times 31.8$ mm. The antenna consists of four parts: main radiator, feeding baluns, reflector, and two parasitic loops. Without using complex filtering circuits, the dual-polarized dipole antenna realizes satisfactory filtering performance and enhanced bandwidth by employing only two parasitic loops. Two specific radiation nulls are thus generated and individually controlled by the two parasitic loops. To further improve the upper stopband selectivity and bandwidth, a simple open-ended stub is added to the arms of the dipole. As a result, the bandwidth can be tuned from 7.4% to 47.6%, and the realized gain is decreased dramatically from 8.6 dBi at 2.7 GHz (in-band) to −10 dBi at 2.9 GHz (out-of-band). For demonstration, a broadband dual-polarized dipole antenna is implemented. Measured results show that the proposed antenna has more than 34 dB port isolation over 48.7% (1.66–2.73 GHz) impendence bandwidth (VSWR < 1.5). The measured in-band gain is about 8.15 dBi with stable 3 dB beamwidth 65.4°±2.4° in the horizontal plane, whereas the out-of-band radiation suppression is more than 17 dB.
108 citations
TL;DR: In this paper, a differential dual-polarized filtering dielectric resonator antenna (DRA) is proposed to achieve high isolation for input ports, and the elaborately designed feeding strips ensure controllable input impedances for integration applications.
Abstract: This communication presents a differential dual-polarized filtering dielectric resonator antenna (DRA). In this antenna, a four-leaf-clover-shaped dielectric resonator is excited with two groups of out-of-phase modes. The novel configuration and differential feeding provide the DRA with high isolation for input ports, and the elaborately designed feeding strips ensure controllable input impedances for integration applications. After integrating with a pair of filtering baluns on the opposite side of the reflecting ground, the proposed DRA also exhibits good out-of-band rejection for each port with a wide stopband and two radiation nulls at band edges. A prototype has been designed and implemented, and reasonable agreement between the measured and simulated results can be observed.
80 citations
TL;DR: In this article, a dual-polarized broadband antenna array for base stations is proposed for the purpose of low profile, low profile and ease of mass production, and printed dipoles are adopted as the dual-Polarized antenna element.
Abstract: A compact $\pm \text{45}^{\circ }$ dual-polarized broadband antenna array is proposed in this letter for base stations. For the sake of structural simplicity, low profile, and ease of mass production, printed dipoles are adopted as the dual-polarized antenna element. To achieve the broadband performance, radiators are designed to be spline-edged bowties, and they are fed by tapered transmission lines. Moreover, to improve the symmetry and stability of the radiation pattern, the Pawsey stub baluns are used to balance the antenna structure. Finally, an eight-element antenna array prototype backed by a folded reflector is fabricated and measured. The compact antenna array has a broad bandwidth of 68% (1.427–2.9 GHz) with a voltage standing-wave ratio less than 1.5 and stable radiation properties to provide international mobile telecommunication services over 2G/3G/LTE systems and L- and S -bands released recently.
78 citations
12 Oct 2018
TL;DR: In this article, a wake-up receiver (WuRX) that achieves −80.5dBm sensitivity with only 6.1 nW of power is presented, where high sensitivity is achieved via a passive pseudo-balun envelope detector (ED) with a high input impedance.
Abstract: A wake-up receiver (WuRX) that achieves −80.5-dBm sensitivity with only 6.1 nW of power is presented. High sensitivity is achieved via a passive pseudo-balun envelope detector (ED) with a high input impedance ( $> 750~\text {k}{\Omega }\;{\|}{ pF) that enables a 30.6-dB passive voltage gain transformer while providing differential output and improving the conversion gain by ${2}{\times }$ compared to a conventional single-ended input passive ED for a given input capacitance. The WuRX is implemented in a 180-nm CMOS process and operates from a 0.4-V supply.
53 citations
TL;DR: In this article, a balanced frequency doubler with 6.5 dBm peak output power at 204 GHz in 130-nm SiGe BiCMOS technology was presented, where an on-chip transformer-based balun was employed to convert the single-ended input signal to a differential signal for balanced operation.
Abstract: This paper presents a balanced frequency doubler with 6.5-dBm peak output power at 204 GHz in 130-nm SiGe BiCMOS technology ( $f_{T}/f_{\max }=210$ /250 GHz). To convert the single-ended input signal to a differential signal for balanced operation, an on-chip transformer-based balun is employed. Detailed design procedure and compensation techniques to lower the imbalance at the output ports, based on mixed mode S parameters are proposed and verified analytically and through electromagnetic simulations. The use of optimized harmonic reflectors at the input port results in a 2-dBm increase in output power without sacrificing the bandwidth of interest. The measured conversion loss of the frequency doubler is 9 dB with 6-dBm input power at 204-GHz output. The measured peak output power is 6.5 dBm with an on-chip power amplifier stage. The 3-dB output power bandwidth is measured to be wider than 50 GHz (170–220 GHz). The total chip area of the doubler is 0.09 mm2 and the dc power consumption is 90 mW from a 1.8-V supply, which corresponds to a 5% collector efficiency.
49 citations
TL;DR: In this paper, a reconfigurable cross-dipole fed with coaxial baluns and a switchable feeding network was designed for antennas with quad-polarization diversity, which can generate vertical and horizontal polarization radiations and the phase of each polarization mode can be switched between 0° and 180°.
Abstract: A design for antennas with quad-polarization diversity is described. The antenna structure is mainly composed of a reconfigurable crossed-dipole fed with coaxial baluns and a switchable feeding network. By controlling the states of p-i-n diodes embedded in the balun feeds, the crossed dipole can generate vertical and horizontal polarization radiations, and the phase of each polarization mode can be switched between 0° and 180°. As for the feeding network, it has four output ports and only two output ports are set to be active to excite the crossed dipole at a time. By integrating the crossed dipole with the feeding network, the resultant antenna can provide four polarization modes, including ±45° linear polarizations (LPs) and dual-orthogonal circular polarizations (CPs). Moreover, the overlapped operation bandwidth of the four polarization modes is more than 35%, and within the bandwidth, the cross polarization level of the LP modes is less than −20 dB and the axial ratio of the CP modes is smaller than 3 dB. Good impedance matching is also achieved for each polarization mode.
44 citations
TL;DR: In this paper, a 6-bit active phase shifter was developed in 0.13-μm-m$ CMOS technology for Ku-band phased arrays, where an improved transformer balun with wriggly stub is applied to split the single input to differential and achieve high balance with reduced chip area.
Abstract: A 6-bit high-accuracy active phase shifter is developed in 0.13- $\mu \text{m}$ CMOS technology for Ku -band phased arrays. Improved transformer balun with wriggly stub is applied to split the single input to differential and achieve high balance with reduced chip area. Two-stage polyphase filter (PPF) generates broadband I/Q signals with high accuracy. A main digital-to-analog convertor (DAC) controls the I/Q amplitude to achieve 6-bit phase resolution, while an auxiliary DAC compensates the amplitude/phase error introduced by balun and PPF. Consequently, high resolution along with low phase/gain error can be achieved. The phase shifter shows measured rms phase error of $0.75 \times 0.32$ mm2 excluding pads.
43 citations
TL;DR: Compared to the other reported dual-polarized dipole antennas, the presented antenna achieves wide impedance bandwidth, high port isolation, stable antenna gain, and HPBW with a simple structure and compact size.
Abstract: A novel design method of a wideband dual-polarized antenna is presented by using shorted dipoles, integrated baluns, and crossed feed lines. Simulation and equivalent circuit analysis of the antenna are given. To validate the design method, an antenna prototype is designed, optimized, fabricated, and measured. Measured results verify that the proposed antenna has an impedance bandwidth of 74.5% (from 1.69 to 3.7 GHz) for VSWR < 1.5 at both ports, and the isolation between the two ports is over 30 dB. Stable gain of 8–8.7 dBi and half-power beamwidth (HPBW) of 65°–70° are obtained for 2G/3G/4G base station frequency bands (1.7–2.7 GHz). Compared to the other reported dual-polarized dipole antennas, the presented antenna achieves wide impedance bandwidth, high port isolation, stable antenna gain, and HPBW with a simple structure and compact size.
37 citations
TL;DR: In this article, the authors present an explicit analysis of the bandwidth and port imbalance of a sub-quarter-wavelength transmission line (t-line) transformer and verifies this with the design of a two-stage D-band power amplifier (PA) series power combining techniques incorporating both stacked heterojunction bipolar transistors (HBTs) and power combining using an 8-way sub-thirdswavelength t-line transformer above 100 GHz.
Abstract: This paper presents an explicit analysis of the bandwidth and port imbalance of a subquarter-wavelength transmission-line (t-line) transformer and verifies this with the design of a two-stage D-band power amplifier (PA) Series power combining techniques incorporate both stacked heterojunction bipolar transistors (HBTs) and power combining using an 8-way sub-quarter-wavelength t-line transformer above 100 GHz The extremely compact power combining methodology leads to a small die area of 062 mm2 and a record 254-mW/mm2 output power per unit die area The PA has been fabricated in a 90-nm silicon germanium BiCMOS technology and produces more than 21-dBm output power over the frequency range of 114–130 GHz with a peak output power of $160~{\mathrm{mW}}\approx 22~{\mathrm{ dBm}}$ at 120 GHz and a 3-dB small-signal bandwidth of 35 GHz This output power is 32% higher than the highest prior art, while the chip area is 77% smaller
36 citations
TL;DR: In this article, a 60 GHz transformer-based voltage-type-combined single-stage stacked field effect transistor (FET) power amplifier (PA) is demonstrated using a 65-nm CMOS process.
Abstract: In this paper, a 60-GHz transformer (TF)-based voltage-type-combined single-stage stacked field-effect transistor (FET) power amplifier (PA) is demonstrated using a 65-nm CMOS process. A stacked-FET structure is adopted in the PA design to overcome the low breakdown voltage limit of MOSFETs. The TF-based voltage-type combiner used in the design has 0.9-dB insertion loss with a compact size of 0.023 mm2. The additional output balun is utilized to transform the differential output of the voltage-type combiner to the single-ended output for testing consideration. The thermal problem of the PA was discovered and improved during measurement. With a 3-V supply, the measured PA achieves the saturated output power ( $P_{\mathrm {SAT}}$ ) of 21.8 dBm, the maximum power-added efficiency (PAEmax) of 12.4%, and a 8.7-dB small-signal gain $(\vert S_{21}\boldsymbol \vert)$ at 60 GHz with the loss of the output balun. Without considering the loss of the output balun, which is 0.825 dB, the measured PA achieves $P_{\mathrm {SAT}}$ of 22.8 dBm, the PAEmax of 15.9%, and a 9.5-dB gain at 60 GHz.
35 citations
TL;DR: In this article, a tunable active differential inductor is used to achieve phase shifts up to 180° in an all-pass phase shifter with a switchable active balanced-to-unbalanced transition circuit.
Abstract: To address the challenging needs of small size, wide bandwidth, and low-frequency applicability, a novel phase shifter implementation is introduced that utilizes tunable active differential inductors within all-pass networks. The inductor tuning is used to achieve phase shifts up to 180°. A switchable active balanced-to-unbalanced transition (balun) circuit is included in front of the all-pass network to complement its phase shift capability by another 180°. In addition, the all-pass network is followed by a variable-gain amplifier to correct for gain variations among the phase shifting states and act as an output buffer. Although active inductors have previously been used in the design of various components, to the best of our knowledge this is the first time that they have been used in an all-pass phase shifter. The approach is demonstrated with an on-chip design and implementation exhibiting wideband performance for S- and L-band applications by utilizing the 0.5- $\mu \text{m}$ TriQuint pHEMT GaAs monolithic microwave integrated circuits (MMIC) process. Specifically, the presented phase shifter $1 \times 3.95~ \text {mm}^{2}$ die area and operates within the 1.5–3-GHz band (i.e., 2:1 bandwidth) with 10-dB gain, less than 1.5-dB root-mean-square (rms) gain error and less than 9° rms phase error. Comparison with the state-of-the-art MMIC phase shifters operating in S- and L-bands demonstrates that the presented phase shifter exhibits a remarkable bandwidth performance from a very compact footprint with low-power consumption. Consequently, it presents an alternative for the implementation of wideband phase shifters where all-passive implementations will consume expensive die real estate.
TL;DR: Two wideband balanced-to-unbalanced (balun) bandpass filters (BPFs) are synthetically designed with three- and four-pole filtering responses, respectively, and their theoretical and simulated results are well confirmed by the circuit model responses with the same impedance values of the simulated microstrip and slotline resonators and the extracted turns ratios of the employed transformers.
Abstract: In this paper, two wideband balanced-to-unbalanced (balun) bandpass filters (BPFs) are synthetically designed with three- and four-pole filtering responses, respectively. Based on the simplified even- and odd-mode equivalent circuits of the proposed three-pole balun BPF, the exact impedance value of the cascaded microstrip sections connected with two balanced ports is first determined in order to attain a perfectly matched S-matrix. By the virtue of the modified two-port transmission-line network with asymmetrical port impedances, a quasi-Chebyshev filtering response for this three-pole balun filter is theoretically presented. Next, to improve the in-band performance, especially at the high frequency, a four-pole balun BPF designed with a folded slotline resonator is proposed. Via the virtually short-ended microstrip stubs of the modified two-port equivalent network, the four-pole frequency response can be directly analyzed with the Chebyshev polynomial function. For these two proposed wideband balun filters, their theoretical and simulated results are well confirmed by the circuit model responses with the same impedance values of the simulated microstrip and slotline resonators and the extracted turns ratios of the employed transformers. Finally, two prototype wideband balun BPFs are fabricated and measured to verify our design predictions.
TL;DR: An in-band full-duplex scheme is proposed for simultaneous power transfer and data delivery in far-field wireless sensor systems, and an RF front-end architecture, here standing for a dual-polarized antenna array with its feeding network, is presented and detailed in this paper.
Abstract: An in-band full-duplex scheme is proposed for simultaneous power transfer and data delivery in far-field wireless sensor systems. To realize two independent links for power and data delivery, a high isolation level between the local transmitter and receiver of the in-band full-duplex system is critical. An RF front-end architecture, here standing for a dual-polarized antenna array with its feeding network, is presented and detailed in this paper. By using the proposed architecture, self-interference can be well canceled within a wide frequency band, leading to a high inter-port isolation level. To demonstrate the performance of such a front-end structure, an on-board prototype has been developed and examined experimentally. Measured results show that the impedance bandwidth of the developed antenna is from 4.5 to 5.8 GHz. The achieved inter-port isolation is higher than 65 dB from 4.4 to over 6.0 GHz, and over 71 dB from 5.36 to 5.82 GHz, indicating a very high self-interference suppression level. Furthermore, RF power and video transferring experiments are carried out, and good consistency with calculated results is observed.
TL;DR: A modified sliding-IF receiver architecture with a suitable local oscillator (LO) frequency plan utilizing a temperature-compensated thin film bulk acoustic-wave resonator (FBAR) completely eliminates the need for a PLL by directly dividing down the fixed FBAR oscillator frequency.
Abstract: This paper presents a 1.8-mW 2.4-GHz channelized receiver for ISM-band applications. Unlike traditional ISM-band radios which typically require a phase-locked loop (PLL) for channelization, we propose a modified sliding-IF receiver architecture with a suitable local oscillator (LO) frequency plan utilizing a temperature-compensated thin film bulk acoustic-wave resonator (FBAR). This strategy completely eliminates the need for a PLL by directly dividing down the fixed FBAR oscillator frequency. An inductor-less current-reuse balun LNA is proposed allowing a low-power wideband matching as well as noise cancelling. The frequency conversion is achieved by a hybrid mixer, which stacks a switching mixer on a switched- $g_{m}$ mixer for current reuse. It also features good voltage headroom and common-mode noise rejection. The FBAR-based Colpitts oscillator achieves the phase noise of −144 dBc/Hz at 3.5-MHz offset. The measured RX gain, noise figure, and in-band IIP3 are 57.8 dB, 15.7 dB, and −18.5 dBm, respectively, without external crystal and on-chip inductors, which allows us to reduce the size and weight of the receiver system. It dissipates 0.86 mW (RX) and 0.92 mW (LO) from a single 1-V supply.
TL;DR: In this article, a stacked-patch antenna based on substrate-integrated suspended line technology is proposed, which is designed to be self-packaged using five substrate layers with embedded air cavities.
Abstract: A novel stacked-patch antenna based on substrate-integrated suspended line technology is proposed. The antenna is designed to be self-packaged using five substrate layers with embedded air cavities. Via is utilized to connect the antenna driven patch with the feed line, and then resonant frequency at 5.2 GHz is generated. U-shaped slot is etched on the antenna driven patch for impedance matching. In order to further extend the impedance bandwidth, a stacked patch with slant slot is introduced and then another resonant frequency at 6.2 GHz is produced. According to the measured results, the antenna element achieves a fractional bandwidth of 17.5% from 5.2 to 6.2 GHz and gain of 9.7 dBi. Based on the antenna element, the eight-element antenna array with feeding network is presented. The microstrip–slotline balun is introduced in the feeding network to achieve 180° phase difference with equal amplitude so that symmetrical radiation patterns are achieved. Simulation and measurement results for the proposed antenna array are in good agreement. In the frequency band from 5.28 to 6.05 GHz, antenna gain of 16.24 dBi with gain flatness variation of 1.5 dB is achieved. In addition, the front-to-back ratio of the self-packaged antenna array is better than 20 dB.
TL;DR: In this article, a dual-mode balun bandpass filter (BPF) with high selectivity is proposed, which is mainly composed of two different types of microstrip-to-slotline transition structures, two identical dualmode stub-loaded resonators, and a pair of balanced outputs.
Abstract: In this letter, a new dual-mode balun bandpass filter (BPF) with high selectivity is proposed. The balun BPF is mainly composed of two different types of microstrip-to-slotline transition structures, two identical dual-mode stub-loaded resonators, and a pair of balanced outputs. First, to convert unbalanced signals from port 1 into balanced signals between port 2 and port 3, two different types of microstrip-to-slotline transition structures are utilized. Afterward, two identical stub-loaded resonators are embedded in the circuit for realizing the dual-mode bandpass response. Furthermore, four transmission zeros generated outside the passband are wisely introduced and well elucidated, thus ensuring high selectivity performance. For demonstration, a sample of balun BPF centered at 2.78 GHz ( $f_{0})$ with 0.5-dB magnitude imbalance and 5° phase imbalance is designed, fabricated, and measured. Both simulation and measurement are in good agreements.
TL;DR: Lower gmCG without degrading the input matching, allows a large scaling factor for common source (CS) stage in noise cancelling technique, and adds a degree of freedom for transconductance of common gate stage (gmCG).
TL;DR: In this article, a front-to-back pattern-reconfigurable antenna based on two dipoles is investigated, which achieves a bandwidth of 31.4% for return loss > 10 dB and a pattern-bandwidth of 20.8% for F/B > 10dB.
Abstract: A front-to-back pattern-reconfigurable antenna based on two dipoles is investigated. The theory for a front-to-back pattern reconfiguration is analyzed. The front-to-back ratio (F/B) is improved by using two folded dipoles. The pattern-reconfigurable antenna is realized by switching two PIN diodes with two broadband baluns. Two parasitic elements are introduced for the improvement of impedance bandwidth and pattern bandwidth. A shorter dipole is added to each folded dipole for further enhancing the pattern bandwidth. Experimental results show that the pattern-reconfigurable antenna achieves a bandwidth of 31.4% for return loss >10 dB and a pattern-bandwidth of 20.8% for F/B > 10 dB and 11.5% for F/B > 15 dB.
TL;DR: In this article, a new differential microstrip feeding method was proposed for dielectric resonator antenna (DRA) and array with low permittivity, where two parallel microstrip lines with differential signals were placed underneath the rectangular DRA to excite its fundamental $\text{TE}^{x}_{\delta 11}$ mode.
Abstract: A new differential microstrip feeding method is proposed for dielectric resonator antenna (DRA) and array with low permittivity. Two parallel microstrip lines with differential signals are placed underneath the rectangular DRA to excite its fundamental $\text{TE}^{x}_{\delta 11}$ mode. A single-port DRA element is first designed with a balun. The measured −10 dB bandwidth is achieved to be 22% around 2.4 GHz, and the in-band realized boresight gain is around 6 dBi. Then, a 2 × 2 differentially fed DRA array is developed, combining series and parallel feeding networks. An 18.7% bandwidth and an average gain of 12.3 dBi are achieved. The effectiveness of our proposed feeding method has been demonstrated by the good agreement between the measured and simulated results.
TL;DR: Two balanced-to-balanced planar diplexers based on magnetically coupled microstrip resonators are proposed in this paper and good differential-mode and common-mode performance is observed in both examples.
Abstract: Two balanced-to-balanced planar diplexers based on magnetically coupled microstrip resonators are proposed in this paper. For the first prototype, each channel/differential-output is composed of a second order single-band balanced bandpass filter based on open-loop resonators. For the second diplexer example, the filters composing the differential outputs are fourth order and are implemented by means of folded stepped-impedance resonators. The design procedure for the differential response is quite straightforward, since it is based on the use of the well-known external quality factor and coupling coefficients concepts. Common-mode is inherently rejected thanks to the benefits of magnetic coupling, which precludes common-mode transmission over a wide frequency range. The proposed structure also offers a high level of channel-to-channel isolation. To demonstrate the usefulness of the proposed idea, the two prototypes are simulated, fabricated, and measured. Good differential-mode and common-mode performance is observed in both examples. Simulations and measurements show good agreement.
Patent•
30 Oct 2018
TL;DR: In this article, a modified lattice, lattice and ladder circuit topology is proposed for a single crystal or polycrystalline bulk acoustic wave (BAW) resonator.
Abstract: An RF circuit device using modified lattice, lattice, and ladder circuit topologies. The devices can include four resonator devices and four shunt resonator devices. In the ladder topology, the resonator devices are connected in series from an input port to an output port while shunt resonator devices are coupled the nodes between the resonator devices. In the lattice topology, a top and a bottom serial configurations each includes a pair of resonator devices that are coupled to differential input and output ports. A pair of shunt resonators is cross-coupled between each pair of a top serial configuration resonator and a bottom serial configuration resonator. The modified lattice topology adds baluns or inductor devices between top and bottom nodes of the top and bottom serial configurations of the lattice configuration. These topologies may be applied using single crystal or polycrystalline bulk acoustic wave (BAW) resonators.
TL;DR: In this article, a broadband unidirectional dipole antenna with a folded dipole, a ground plane and a U-shaped structure is presented. But the antenna is not suitable for high frequency bands.
Abstract: By loading a parasitic patch, a novel broadband unidirectional dipole antenna is presented. The antenna fed by a coaxial balun consists of a folded dipole, a parasitic patch, and a ground plane. The folded dipole has two bowtie elements and a U-shaped structure. In the low operating band, the folded dipole works as an electric dipole and the parasitic patch works as a director. By using the director, the impedance matching performance is improved dramatically. In the high operating band, the two bowtie elements are as an electric dipole, and a magnetic dipole is formed by combining the parasitic patch and U-shaped structure. A new resonant frequency is generated and the impedance bandwidth is enhanced due to the magnetic dipole. Measured results show that an impedance bandwidth of 1.61–3.45 GHz (72.7%) for S 11 ≤ −15 dB is obtained. Stable radiation patterns, low cross polarization, and a maximum gain 8.77 dBi are achieved.
TL;DR: In this article, a switchless dual-band, dual-mode power amplifier (PA) has been developed for multioctave operation, which operates as a balun at highband frequencies and the coupled line at low-band frequencies.
Abstract: In this paper, a switchless dual-band, dual-mode power amplifier (PA) has been developed for multioctave operation. For the switchless dual-band operation, we proposed a new coupled-line-based diplexer structure. The proposed diplexer operates as a balun at high-band frequencies and the coupled line at low-band frequencies. To better understand the proposed diplexer structure, a detailed analysis is performed based on a coupled-line theory. The interstage and output-stage matching networks of the PA are designed by using the proposed diplexer. To maximize the power-added efficiency (PAE) of the designed PA, turn off the unused band PAs and decide the optimum off-state bias condition of transistors. The designed dual-band, dual-mode PA is fabricated with commercial 0.25- $\mu \text{m}$ GaN HEMT process. The fabricated PA shows over 15-dB small-signal gain at 5–11 GHz in the low-band mode and 9–18 GHz in the high-band mode. The measured average output power and PAE are 35 dBm, 23% in the low-band mode and 37 dBm, 26% in the high-band mode.
TL;DR: In this paper, a novel wideband four-arm sinuous antenna with dual circular polarizations (CPs) and unidirectional radiation is proposed, which is realized in a conical form and no ground plane or absorptive cavity is required to obtain unideal radiation.
Abstract: A novel wideband four-arm sinuous antenna with dual circular polarizations (CPs) and unidirectional radiation is proposed. Different from the conventional designs, this sinuous antenna is realized in a conical form and no ground plane or absorptive cavity is required to obtain unidirectional radiation. The beamforming network for dual circularly polarized operations consists of a wideband quadrature coupler and two wideband baluns, and an auxiliary feeding patch is introduced to facilitate the connection between baluns and sinuous arms. The design of baluns and coupler is inspired from the printed exponentially tapered microstrip balun and broadside-coupled microstrip coupler, respectively. The dynamic differential evolution algorithm is employed to optimize the geometry of coupler for optimal performance. For both polarizations, the presented antenna has wide impedance bandwidth, good axial ratio, moderate realized gain, and front-to-back ratio within 2–5 GHz. An antenna prototype is fabricated and tested. The agreement between simulation and measurement results validates the proposed antenna framework. The demonstrated antenna has advantages of wide bandwidth, dual CPs, unidirectional radiation, lightweight, and low cost, and is promising for applications in wireless systems.
TL;DR: In this paper, the authors proposed a microwave ablation (MWA) antenna design that uses minimally invasive interstitial antennas for heating tumors to cytotoxic temperatures by using coaxial cable feed lines to deliver the microwave energy.
Abstract: Microwave ablation (MWA) is a promising therapeutic technique that uses minimally invasive interstitial antennas for heating tumors to cytotoxic temperatures [1], [2]. Over the years, numerous MWA antennas have been reported in the literature (e.g., [3]-[15]). MWA antenna designs typically use coaxial cable feed lines to deliver the microwave energy to the active part of the antenna. Due to the unbalanced nature of coaxial cables, current can flow on the outer surface of the outer conductor. If not appropriately suppressed, this current can cause unwanted heating of healthy tissue along the antenna?s insertion path. Moreover, in such situations, the input impedance of the antenna becomes dependent on the insertion depth.
TL;DR: In this paper, a compact high-power SiGe Ka-band balanced frequency doubler is presented, using a compact single-footprint four-way transformer input balun, wideband matching, and high fundamental rejection simultaneously.
Abstract: A compact highly efficient high-power SiGe Ka-band balanced frequency doubler is presented. Using a compact single-footprint four-way transformer input balun, wideband matching, and high fundamental rejection were achieved simultaneously. A cascode topology with very low base impedance termination was utilized for stable operation and high-voltage swing at the output. Two cascode differential pairs form a common-centroid configuration, resulting strong enhancement in output power, power-added efficiency (PAE), fundamental rejection, and robustness to process and supply variation. The proposed Ka-band cascode balanced frequency doubler was implemented in a 0.13- $\mu \text{m}$ SiGe BiCMOS technology. Measured results show 13-dBm output power with 22% peak PAE at 34 GHz for a −1-dBm input power. The 3-dB conversion gain bandwidth is from 25 to 40 GHz, fully covering Ka-band. Peak fundamental suppression is 74.5 dB at 33 GHz, and it is higher than 35 dB over Ka-band. No performance degradation is observed after 24-h RF stress test. To the author’s best knowledge, this paper has the highest efficiency, the highest output power/power density, the highest conversion gain without output buffers, and the higher or comparable fundamental rejection among any Si-based frequency doublers. Therefore, this doubler will be a promising solution for efficient and high-power local oscillator generation in 5G wireless phased-array communication system.
TL;DR: In this paper, a dual-polarized antenna with a large bandwidth and a high front-to-back ratio was proposed for outdoor base station applications, and the back-lobe suppression technique can be applied easily to base station antennas.
Abstract: A novel dual-polarized antenna, with a large bandwidth and a high front-to-back ratio, is proposed in this communication. The antenna is composed of printed dipoles and tapered baluns above a square ground plane to yield a wide bandwidth. Semicylindrical walls are loaded on the edge of the ground plane to suppress the back lobe and produce a stable gain. Backward radiation is suppressed by the diffraction effect of the semicylindrical sidewalls. Simulation shows that the back-lobe level can be reduced below −13 dB in a large frequency range without degrading the antenna bandwidth. The proposed antenna is fabricated and the measured results show that it has an impedance bandwidth of 69.6% (1.46–3.02 GHz) for voltage standing wave ratio <1.5. Within the bandwidth, the gain varies between 7.1 and 8.4 dBi, and the front-to-back ratio is above 20 dB. The proposed antenna is suitable for outdoor base station applications, and the back-lobe suppression technique can be applied easily to base station antennas.
TL;DR: In this paper, a novel broadband horizontally polarized (HP) omnidirectional antenna is proposed for meteor-burst communication system in VHF, which is composed of three bowtie dipoles, which are concentrically placed to form a loop antenna.
Abstract: A novel broadband horizontally polarized (HP) omnidirectional antenna is proposed for meteor-burst communication system in VHF. The proposed antenna is composed of three bowtie dipoles, which are concentrically placed to form a loop antenna. The bowtie dipole is shorted at the terminal by folded elements in order to reduce antenna size. The bowtie dipoles are fed by a three-way power divider. A slotted line balun is employed to achieve broadband impedance matching and realize balanced-to-unbalanced transformation. The designed HP omnidirectional antenna exhibits a fractional bandwidth of 24.7% with VSWR < 2 ranging from 39 to 50 MHz. Uniform omnidirectional radiation patterns in the azimuth plane with HP have been obtained. The loop antenna provides a relatively low gain of no more than 1.5 dBi. Therefore, a two-element HP antenna array is developed to enhance its gain. In order to reduce longitudinal dimension of the array, the two loop antenna elements are placed in reverse and employ differential feeding method to realize in-phase current. Both the simulation and measured results are used to verify the design approach.
TL;DR: In this article, a new design method for an asymmetric microstrip-to-coplanar stripline (CPS) transition based on the analytical electromagnetic model is presented, where the cross section at each stage of the transition is analyzed through conformal transformation, and the corresponding line impedance is calculated.
Abstract: A new design method for an asymmetric microstrip-to-coplanar stripline (CPS) transition based on the analytical electromagnetic model is presented. The cross section at each stage of the transition is analyzed through conformal transformation, and the corresponding line impedance is calculated. Then, the ground linewidth on the substrate bottom is adjusted to form an optimal Klopfenstein impedance taper. To demonstrate the design method, a transition between a 50- $\Omega $ microstrip line and a high-impedance CPS line ( $147~\Omega$ ) was implemented. Good transition performance with more than 10-dB return loss and less than 1-dB insertion loss was obtained for frequency ranges of 6–40 GHz.
TL;DR: This paper presents a millimeter-wave Doherty PA implemented in a standard 65-nm CMOS technology with a Marchand balun with balance compensation designed to combine the output power with reduced power loss and a nonlinear driver used to drive the peaking amplifier.
Abstract: This paper presents a $V$ -band Doherty power amplifier (PA) which is implemented in a standard 65-nm CMOS technology. The voltage combination technique is used to realize the millimeter-wave Doherty PA without the $\lambda $ /4 transmission lines. A Marchand balun with balance compensation is designed to combine the output power with reduced power loss. Moreover, a nonlinear driver is used to drive the peaking amplifier to enhance the output power and the turn-on speed of it. The power-added efficiency (PAE) of this PA at the 6-dB power back-off point is 8.7% and the peak PAE reaches 16.8%. The small signal power gain is 18 dB, and the maximum output power is 14.9 dBm. The core circuit only costs 0.195 mm2 chip area as no $\lambda $ /4 transmission lines.