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A low-profile and shared aperture dual-polarized (DP) omnidirectional antenna by reusing the structure of an annular quasi-dipole array is presented. The proposed antenna consists of a center-fed circular patch antenna, an annular quasi-dipole array, a wideband one-to-four power divider integrated with the center-fed circular patch antenna, and two annular strips. The center-fed circular patch antenna is utilized as the driven element for the vertically polarized (VP) radiation. The annular quasi-dipole array fed by the one-to-four power divider produces horizontally polarized (HP) radiation. Simultaneously, it also acts as the VP director to improve VP gain and bandwidth. Besides, the two annular strips enhance the HP omni-directivity and gain. In this way, the VP and HP share the same aperture to improve the profile utilization rate effectively. Due to the symmetry of the basic antenna structure, stable DP donut patterns are obtained within the entire operating bandwidth. For demonstration, a 4.1–5.0 GHz prototype is designed, fabricated, and measured. Under a low profile of $0.13\lambda _{0}$ , the prototype realizes a −10 dB overlapped bandwidth of 20%, high port isolation of above 35 dB, and stable DP donut patterns with horizontal gain larger than 1.8 dBi. [ABSTRACT FROM AUTHOR]

The fabrication process of an advanced transparent cyclic olefin copolymer (COC)‐based laminate is introduced, along with the laser cutting technology for circuit pattern. Then, a three‐way Gysel divider with an equal power‐dividing ratio is reviewed, designed and measured, based on the proposed COC‐based laminate. The measured results are compared to those from a similar three‐way Gysel divider based on traditional RT/duroid 5880 laminate, from which we can see that COC‐based laminate has the advantage of lower loss, with other advantages such as low cost, easy realization, high‐precision, and even the transparency. This laminate can be an excellent candidate for a substrate at microwave or millimeter‐wave circuits. [ABSTRACT FROM AUTHOR]

A wideband substrate integrated waveguide (SIW) power divider based on half mode analysis is presented in this article. The structure is constructed by two substrate layers and three metal layers. Two symmetrical longitudinal apertures etched on the middle ground are introduced to realize the equal power division, and couple the signal from the SIW to the upper layer output ports simultaneously. Two fork‐type microstrip lines on the top metal layer are used to improve the bandwidth of the power divider. The equivalent circuit based on the half mode analysis method is presented for theoretical analysis and further design of the power divider, and good impedance matching can be obtained accordingly. For demonstration, a power divider prototype with the dimension of 48 × 73 × 1.38 mm3 is designed, fabricated, and measured. Good agreement is observed between the simulated and measured results. The measured return loss of the SIW power divider is better than 12 dB in the frequency range of 6.2 ~ 10.3 GHz, and the insertion loss is around 1.6 dB over the entire frequencies of interest. [ABSTRACT FROM AUTHOR]

An admittance‐inverter‐based two‐section topology is proposed for filtering power dividers in this article aiming at high and wideband output isolation. Different from the classic two‐section Wilkinson power dividers, the bulky quarter‐wave transmission lines are removed and replaced by using two pairs of admittance inverters, which are realized by the input external quality factor (Qe‐in) and coupling coefficient (k12), respectively. Since the electric size of these coupling effects (Qe‐in and k12) are negligible, a significant size reduction is easily realized. In addition, two isolation elements are added between the input resonators and the output ones, respectively. Two‐prefect absorption points are accordingly realized in |S23|, indicating wider and higher output isolation compared with the reported designs using one isolation element. For demonstration, one two‐section filtering power divider is designed and fabricated. The circuit size is only 0.009λg2, while the output isolation exceeds 41.5 dB over the passband. [ABSTRACT FROM AUTHOR]

Aiming at high and wideband output isolation, a new topology of filtering power divider based on complex isolation impedance and surface wave mitigation techniques is proposed. Different from previously published filtering power dividers using pure resistor, an analytical design method by using complex impedance is proposed in this article. To formula the complex impedance, the LC equivalent circuit model is introduced, and the closed-form derivation is given accordingly. Based on the calculated impedance, high isolation can be theoretically realized in circuit level. However, the output isolation is limited below 20 dB in practical EM simulations. To solve this issue, the filtering power divider is further investigated in field level. To reduce the crosstalk between adjacent filtering channels, the surface wave mitigation techniques are investigated. Accordingly, a 16-dB enhancement of output isolation is realized, without sacrificing other filtering specifications. For experimental verification, a filtering power divider is designed, fabricated, and measured. A significant size reduction and 36-dB output isolation with over 500% isolation bandwidth can be observed, verifying the validity of the proposed design method. [ABSTRACT FROM AUTHOR]

This study proposes a compact structure of the three‐way Gysel power divider with arbitrary power dividing ratio, which has a significant difference from existing N‐way ones with a common node in the centre of the circuit. First, existing equations are reviewed, and new analytical closed‐form equations are derived according to the proposed structure. The frequency bandwidths, affected by the parameters of isolation networks are investigated in detail and optimised for performance balance. For verification, the proposed three‐way Gysel power dividers are calculated, optimised and fabricated at the centre frequency of 3.5GHz with different dividing ratios of 1:1:1 and 1:2:3, respectively. Moreover, the equations are derived to design the N‐way Gysel power divider. [ABSTRACT FROM AUTHOR]

A bandpass push–pull high power amplifier (PA) based on substrate integrated waveguide (SIW) filtering balun power divider is proposed in this article. The filtering characteristic of the PA is realized by the complementary split rings resonators (CSRRs) defected in the balun based on the SIW. Inherent to the middle metal plane of the SIW balun, the 180° phase difference power division can be achieved. Due to the natural differential characteristic of the balun, the proposed design can produce second-harmonic suppression. Greater output power is obtained owing to the filtering balun power combiner. For the fabricated bandpass push–pull PA, it exhibits high-selectivity bandpass response and good PA performance with the peak power-added efficiency (PAE) of 48.7% at 38.5-dBm output power. [ABSTRACT FROM AUTHOR]

Two new types of multi-functional RF wide-band differential-mode-to-single-ended filtering power dividers are reported in this brief. Their first configurations exploit half-wavelength ring resonators and coupled-line sections to attain common-mode suppression throughout a broad spectral range. Furthermore, asymmetrical coupled-line stages are incorporated in more-advanced schemes to enlarge upper-stopband bandwidth. Two demonstrative microstrip prototypes for the different structures of this RF tri-functional circuit concept that operate at the 1.7–2.7-GHz 4/5-generation long-term-evolution band are built and tested. [ABSTRACT FROM AUTHOR]

Two novel high selectivity balanced-to-unbalanced filtering power dividers using ring resonators are proposed. The even-/odd-mode analysis method is applied to obtain the design equations at the operating frequency. The ring resonators can bring two transmission zeros in each side of the passband for the differential mode for the filtering power divider (structure I). Moreover, the three-quarter wavelength transmission lines are applied to produce the additional two transmission zeros of differential mode for structure II, which can further improve the differential-mode harmonic suppression and common-mode suppression. Two fabricated prototypes with 4-dB bandwidths of 11.2% and 11.6% are designed and measured to prove the proposed methods. All the structures show good performances for differential-mode power division and common-mode suppression. [ABSTRACT FROM AUTHOR]

This paper presents an automatic impedance transforming technique to extend the radio frequency rectifier input power range with high conversion efficiency. The rectifier employs two branches of subrectifier, each achieving impedance matching at high and low input power ranges. Then, the two branches are connected by a $\lambda/4 $ T-junction power divider. With such configuration, the input impedance of the two subrectifiers are transformed automatically, allowing the impedance matching over a wide input power range. In this way, the injected power can be optimally delivered to the subrectifiers, achieving a high efficiency over this wide input power range. This scheme manages to eliminate the power detetor for branch selection and can be applied to both single- and dual-band rectifiers with a reduced design difficulty. For validation, a single-band rectifier working at 915 MHz and a dual-band rectifier at 915/2450 MHz are implemented. Design analysis on the single- and dual-band rectifiers is carried out. The measurement results show that 68% maximum efficiency is achieved for the single-band (915 MHz) rectifier, and the input power range for the efficiency >70% of the peak efficiency is from −5 to 31 dBm. Besides, the dual-band rectifier shows 66% and 58% peak efficiencies at 915 and 2450 MHz, respectively. The input power range is from −6 to 33 dBm for the efficiency >70% of its peak value at 915 MHz, while from 10 to 32 dBm at 2450 MHz. These indicate that the input power range with high efficiency is extended. [ABSTRACT FROM AUTHOR]

In this paper, $N$ -way Gysel power dividers with arbitrary power-dividing ratio are studied by using node voltage and current method for the first time. Closed-form analytical equations are derived for the design of the proposed Gysel power divider with arbitrary power division on arbitrary terminated impedance. Parameters that might influence the frequency bandwidth are investigated and optimized to achieve balanced performance. For verification, 3-way and 6-way Gysel power dividers are, respectively, designed, fabricated, and measured at a center frequency of 3.45 GHz, with dividing ratio 1:1:1, 1:2:3, 1:1:1:1:1:1:1, and 1:1.2:1.2:1.5:1.5:2, respectively. Good agreements can be observed among expected, simulated, and measured results, indicating the validity of the proposed strategies. [ABSTRACT FROM AUTHOR]

One kind of miniaturized filtering power divider (FPD) with a new topology is proposed. For previously published FPDs, the isolation resistors were usually added with additional quarter-wave ($\lambda $ /4) transmission lines for output isolation. In this paper, $\lambda $ /4 transmission lines are removed, and the resistor is added to the loaded resonator for the miniaturized design. By regarding the input external quality factor ($Q_{e\text {-in}}$) as an admittance inverter, the indispensable 90° delay can be easily realized. To further improve the miniaturization, the dual-composite right-/left-handed (D-CRLH) resonators are adopted; therefore, the overall sizes of the resulting FPDs can be smaller than $0.012\lambda _{g}^{2}$. Moreover, the equivalent circuit of the proposed FPD is investigated for the performance improvement. Input $Q_{e\text {-in}}$ should be double of output $Q_{e\text {-out}}$ for good matching, and good isolation can be obtained by appropriately utilizing $Q_{e\text {-in}}$. For demonstration, three D-CRLH FPDs are designed for narrowband, wideband, and dual-band applications. Satisfactory agreements between the measured results and theoretical expectations are observed, verifying the validity of the proposed design concepts. [ABSTRACT FROM AUTHOR]

Four novel architectures of wideband five-port single-ended-to-balanced power dividers with broadband common-mode suppression are proposed in this paper. The bandpass filtering capability with/without close-to-passband transmission zeros are also incorporated in some of them to obtain multifunctional single-ended-to-differential-mode filtering/power division operation. Two ideal 180° phase inverters are used to replace the conventional half-wavelength transmission line-based inverters in the basic power divider structure so that wideband common-mode rejection and a smaller circuit size are achieved. Quarter-wavelength transmission lines and coupled-line sections are exploited to simultaneously realize the bandpass filtering and wideband power division functionalities. Each five-port power divider exhibits broadband 3-dB single-ended-to-balanced power division, high in-band input–output power-matching levels, high in-band power isolation levels between the two balanced outputs and wideband common-mode rejection. The theoretical analysis, parametric study, and design procedure for the conceived single-ended-to-differential-mode power dividers are provided. Furthermore, for experimental and demonstration purposes, four microstrip prototypes designed at 1 GHz are manufactured and characterized. [ABSTRACT FROM AUTHOR]

A compact filtering power divider is proposed with very wide stopband suppression in this letter. First, the dual‐composite right‐ and left‐handed (D‐CRLH) resonator is employed, while one extended stopband can thus be achieved due to its inherently slow‐wave response. Secondly, one out‐of‐phase feeding scheme is introduced to realise D‐CRLH filtering power divider. By putting the input and output ports on the different sides of D‐CRLH resonators, the mismatching can be realised for the harmonics below 10 GHz and wide stopband suppression is obtained accordingly. For experimental verification, a compact filtering power divider is designed, fabricated, and measured. Wide stopband suppression is observed until 5f0 without using bandstop structures or complex coupling topology. [ABSTRACT FROM AUTHOR]

A novel 6-port balanced network with high unequal power division ratio using shorted coupled lines is proposed in this letter. The design parameters of the proposed power divider are analyzed according to transmission line theory. Two double-sided parallel-strip line 1808 phase inverters loaded with 4 isolation resistors are used to realize high isolation for the power dividing output ports. A planar balanced network with bandwidth of 40.5% (power division ratio: 1:10) for the differential mode and wideband 23% common mode suppression is designed and fabricated. The measured results show good agreement with the theoretical expectations. [ABSTRACT FROM AUTHOR]

Abstract: Two novel wideband balanced‐to‐unbalanced power dividers based on transmission lines and coupled lines are proposed in this article. Multifunction can be realized without cascading single devices with common mode suppression. The desired power divider configurations can be obtained using the even/odd‐mode characteristic impedance of the coupled lines and characteristic impedance of the transmission lines. A resistor in the middle of two single‐ended ports is used to realize isolation between output ports. Two prototypes of wideband balanced‐to‐unbalanced power dividers operating at 2.3 GHz with differential‐mode bandwidths of 79.6 and 134.1% are designed and fabricated. The theoretical and measured results are in good agreement and show good in‐band performances. [ABSTRACT FROM AUTHOR]

Three novel wideband balanced-to-unbalanced filtering power dividers based on coupled lines are proposed in this paper. Multifunctional power dividers can replace various cascaded single devices to decrease integration mismatching loss and circuit size. The wideband response can be easily realized by the coupled lines structures. To further improve the differential-mode passband selectivity, open/shorted coupled lines and half-wavelength open stubs are applied to introduce two transmission zeros near the passband, respectively. In addition, a resistor in the middle of two single-ended ports can be used to realize isolation between out ports. To verify the proposed concepts, three prototypes of wideband balanced-to-unbalanced filtering power dividers operating at 2 GHz are designed and fabricated with the 4-dB differential-mode bandwidths of 80.5%, 71.5%, and 80%. All the structures show good performances for differential-mode out-of-band suppression, common-mode suppression, and isolation. [ABSTRACT FROM PUBLISHER]

A compact tunable power divider is proposed in this brief. The power divider can achieve a wide frequency tuning range and good matching and isolation performances. Theoretical equations for the characteristic impedance and the electrical length of the power divider are derived. For demonstration, a prototype working at 1.5 GHz as the center frequency is designed and fabricated. The measured results show that the power divider can be effectively tuned within the frequency range of 104% (0.83–2.4 GHz) with a return loss and isolation better than 20 dB and insertion loss varying between −3.3 dB and −3.5 dB. [ABSTRACT FROM PUBLISHER]

Two novel wideband balanced networks with wideband common mode suppression and arbitrary power-dividing ratio are proposed in this paper. The differential/common mode equivalent circuits of the balanced networks can be easily reduced based on the matrix transformation. Microstrip-slotline 180° phase inverters loaded with four isolation resistors are used to realize high isolation for the power division output ports. Two planar wideband equal and unequal power division balanced networks with bandwidths of 33% of (1:1, equal) and 39% (1:2.22, unequal) for the differential mode and over 120% common mode suppression (0.96–3.6 GHz, |Scc21, 31| < –10 dB) are designed and fabricated. [ABSTRACT FROM AUTHOR]

A novel narrow‐band balanced filtering network using coupled lines loaded with stubs is proposed in this letter. Two Wilkinson power dividers using coupled lines are used to realise the six‐port balanced network. Wideband common mode suppression and power division isolation can be achieved due to the loaded open/shorted stubs. A narrow‐band balanced filtering network for the WLAN band is designed. Good agreements can be found between the simulation and measurement results. [ABSTRACT FROM AUTHOR]

A novel wideband balanced-to-unbalanced power divider using symmetrical transmission lines is proposed. Due to the symmetry of the power divider circuit, even/odd-mode analysis method is applied to derive the even/odd-mode values and transmission line characteristic impedance. A resistor in the middle of two single-ended output ports is used to realize high isolation for the power division ports. One prototype of the wideband balanced-to-unbalanced power divider operating at 2.2 GHz (1.24–3.20 GHz) is designed and measured to prove the proposed methods. [ABSTRACT FROM PUBLISHER]

A compact reconfigurable circuit performing as either Single Pole Double Throw switch or power divider is proposed and demonstrated, based on the concept of modes match and impedance match between substrate integrated waveguide (SIW) and half-mode SIW (HMSIW). A switchable HMSIW unit is first proposed and then followed by the design of the reconfigurable circuit. For demonstration, the proposed circuit is designed and fabricated on the substrate of Rogers 5880LZ with thickness 1.026 mm. When the circuit works as a switch and Port 2 is at ON-state, the measured S11 < -15 dB, S22 < -13 dB, S21 > -1.5 dB, and S23 and S13 < -27 dB; meanwhile, when the circuit performs as a power divider, the measured S11 < -14.5 dB, and S21 and S31 > -4.35 dB, over the frequency band from 4.6 to 5.3 GHz. The good performances show the advantages of proposed circuit topology, which can be an excellent candidate for multifunctional microwave or millimeter-wave circuits. [ABSTRACT FROM PUBLISHER]

A dual‐band balanced‐to‐unbalanced filtering power divider by coupled ring resonators is proposed. Two passbands can be easily realised by the two coupled ring resonators. Three transmission zeros near the two passbands are used to improve the selectivity. The common mode can be easily suppressed by the bandstop performance of the open stubs. A fabricated prototype (εr = 2.65, h = 1 mm, tanδ = 0.003) with centre frequencies located at 2.82 and 3.22 GHz is designed and measured to prove the proposed methods. [ABSTRACT FROM AUTHOR]

Two new wideband in-phase and out-of-phase balanced power dividing/combining networks are proposed in this paper. Based on matrix transformation, the differential-mode and common-mode equivalent circuits of the two wideband in-phase and out-of-phase networks can be easily deduced. A patterned ground-plane technique is used to realize the strong coupling of the shorted coupled lines for the differential mode. Two planar wideband in-phase and out-of-phase balanced networks with bandwidths of 55.3% and 64.4% (\vert S{ dd21,31}\vert<4\ {\ {dB}}) for the differential mode with wideband common-mode suppression are designed and fabricated. The theoretical and measured results agree well with each other and show good in-band performances. [ABSTRACT FROM PUBLISHER]

An unequal power divider with tunable operating frequency is proposed for the first time, in which the operating frequency can be tuned over 100% around the center frequency. The theoretical analysis for the characteristic impedance and the electrical length are presented. A prototype with the tunable frequency from 0.85 GHz to 2.4 GHz is designed and fabricated. Good agreements can be observed between the simulated and measured results. [ABSTRACT FROM PUBLISHER]

A novel wideband balanced-to-balanced network with unequal power division is proposed in this letter. Two open stubs and half-wavelength transmission lines are used to realize wideband common mode suppression, two ideal double-sided parallel-strip line (DSPSL) 180 ^\circ phase inverters with isolation resistors are used to realize high isolation for the power dividing output ports. A planar wideband balanced network with bandwidth of 38.6% (power division ratio: 1:2^2) for the differential mode and over 113.6% common mode suppression (1.06–3.56 GHz, $| S_{{cc}21,31}| < -10\ \text{dB}$) is designed and fabricated. [ABSTRACT FROM PUBLISHER]

A compact four-way dual-band microstrip power divider is investigated and demonstrated in this letter. The proposed divider reduces the number of transmission line sections by decomposing a single dual-band transformer into a four-way power divider. The theoretical equations for isolation structures and the design procedures of the power divider are presented. For demonstration, a prototype operating at 1 and 2 GHz is fabricated and measured. Good agreements can be observed between the simulated and measured results. [ABSTRACT FROM PUBLISHER]

In this article, two novel topologies of compact‐size dual‐band single‐ended‐to‐balanced power dividers that are loaded with open‐ and short‐ended stubs are presented. Quarter‐wavelength open‐ended stubs and half‐wavelength short‐ended stubs are respectively exploited in the proposed dual‐band power‐divider configurations to incorporate the dual‐band functionality into them for flexibly‐adjustable dual‐frequency‐ratio specifications. Each engineered five‐port power‐divider circuit features high in‐band input/output power‐matching levels, high in‐band power‐isolation levels between the two differential‐mode outputs, and high common‐mode‐rejection levels in a broad spectral range. Two microstrip prototypes designed at 0.9/1.8 GHz (GSM bands) and 1.57/2.45 GHz (GPS and WLAN bands) are constructed and characterized for experimental‐demonstration purposes. [ABSTRACT FROM AUTHOR]

In this article, four wideband power dividers (two are filtering power dividers) using single‐ and double‐layer periodic spoof surface plasmon polaritons (SSPPs) are proposed. Double‐sided parallel‐strip line is used to realize the wideband and low loss for the double‐layer SSPPs. T‐shaped SSPPs power dividers with large bandwidth, wideband isolation, and low loss using double‐layer SSPPs to single‐layer SSPPs transition are realized. Conventional coplanar waveguide is used as the output ports for the single‐layer SSPPs. Moreover, two new SSPPs power dividers with filtering performance are realized with adding via holes in the double‐layer SSPPs. The theoretical analysis, parametric study, and design procedure for these wideband power dividers are illustrated. In addition, for validity demonstration, four wideband SSPPs power dividers are fabricated in microstrip technology and characterized. Good agreements can be observed between the measured and simulated results, indicating good potential applications in the integrated plasmonic devices. [ABSTRACT FROM AUTHOR]