dB Power Divider Research Articles

A simple design of reconfigurable feeding network for antenna array beam scanning

In this letter, a simple approach to design a reconfigurable feeding network (RFN) for antenna array beam scanning is presented. By combining a 3 dB power divider and a reconfigurable delay line group (RDLG), the two output signals with 2m+n sets of uniformly distributed phase gradients (PGs) can be obtained. And by adopting multi two-output RFNs and multi-stage design, a RFN for generating 2m+n continuously distributed beams is constructed. For verifying the design method, a microstrip four-output RFN for generating four scanning beams is implemented, fabricated and measured. The measured results are consistent with the theoretical analysis, which provides the validity of the design. And the design of the RFN can be used as a candidate of the feeding network for antenna array beam scanning.

A 220 GHz Orthogonal Modulator Based on Subharmonic Mixers Using Anti‐Paralleled Schottky Diodes

In this paper, A 220 GHz orthogonal modulator based on two symmetrical subharmonic mixers is designed, analyzed and measured, where the mixers are implemented basde on antiparallel Schottky diodes. The orthogonal modulator consists of a 90° phase shifted 220 GHz 3 dB coupler, two sub-harmonically pumped mixers and an in-phase 110 GHz 3 dB power divider. The IF output signals are in-phase (I) branch and quadrature (Q) branch operating from DC±3.5GHz. In the back to back experimentaltests, it is shown that the conversion loss of the two 220 GHz I/Q mixers is less than 30 dB when the IF operating frequency is DC−3.5 GHz, IF input power is −10 dBm and the LO power is around 6 mW. Based on floating-point simulation, the amplitude and phase imbalance of the I/Q mixer are less than 0.2 dB and 2 degree respectively. When the 220 GHz modulator and demodulator are set in a back to back configuration, a signal-to-noise ratio of 21 dB can be obtained using the 16QAM modulation type.

Design and realization of a single klystron-based radio frequency system for a radio frequency quadrupole and a drift tube linac

This work describes the design and realization of a radio frequency (RF) system with a single klystron to power two conjunct independent cavities, namely, an RF quadrupole (RFQ) and a drift tube linac (DTL). In contrast with a two-klystron scheme, an RF system that adopts a single-klystron scheme for two accelerating cavities exhibits simpler configuration, smaller occupation area, and lower cost. However, the low intrinsic flexibility of the single-klystron scheme needs to be compensated by independent adjustment of RF field phases and amplitudes inside the two cavities. A proposed RF system design based on the single-klystron scheme includes a 4.77 dB power divider, an adjustable power attenuator, and a phase shifter. The power attenuator and phase shifter are set in different branches of the RF power transmission line. This design is used to power an RFQ and a downstream DTL in the Compact Pulsed Hadron Source (CPHS) at Tsinghua University. During commissioning, the amplitudes inside the RFQ and DTL and the relative phase difference between them can be adjusted independently. The 13 MeV proton beam commissioning result verifies the design parameters and effectiveness of the single-klystron-based RF system. A proton beam energy of 12.92 MeV and a beam peak current of 41.2 mA at the exit of DTL were achieved, and the beam transmission from the entrance of RFQ to the exit of DTL reached 88.6%.

Inverse design of digital nanophotonic devices using the adjoint method

A high-efficiency inverse design of “digital” subwavelength nanophotonic devices using the adjoint method is proposed. We design a single-mode 3 dB power divider and a dual-mode demultiplexer to demonstrate the efficiency of the proposed inverse design approach, called the digitized adjoint method, for single- and dual-object optimization, respectively. The optimization comprises three stages: 1) continuous variation for an “analog” pattern; 2) forced permittivity biasing for a “quasi-digital” pattern; and 3) a multilevel digital pattern. Compared with the conventional brute-force method, the proposed method can improve design efficiency by about five times, and the performance optimization can reach approximately the same level. The method takes advantages of adjoint sensitivity analysis and digital subwavelength structure and creates a new way for the efficient and high-performance design of compact digital subwavelength nanophotonic devices, which could overcome the efficiency bottleneck of the brute-force method, which is restricted by the number of pixels of a digital pattern, and improve the device performance by extending a conventional binary pattern to a multilevel one.

Spoof surface plasmonic waveguide devices with compact length and low-loss

A spoof surface plasmon polaritons (SSPPs) waveguide structure with periodic T-grooves is proposed and investigated in this paper. Compared to the conventional plasmonic waveguide with periodic rectangular-grooves, the proposed waveguide support the guided SSPPs wave with enhanced propagation confinement. Moreover, the waveguide with T-grooves can achieve 39.4% decrease in length compared with the rectangular-grooves waveguide. The propagation properties of the SSPPs with enhanced confinement are able to improve by adjusting the shape dimensions of T-grooves. The effects of bend radius of 90° T-grooves waveguide on propagation performance are analyzed, and the good transmission characteristics of waveguides with small bend radius are verified. The experimental verifications of the T-grooves plasmonic waveguide filter and 3 dB power divider in microwave region are realized, S21-parameter of waveguide filter is very close to 0 dB from 0 GHz to 5.6 GHz. And 3 dB power divider achieves very good power equipartition from 0 GHz to 5.5 GHz.

Design of T-Split Power Divider Using Double Ended Spur-Line DMS

Power dividers and power combiners are passive microwave components for power dividing and power combining. In this article one T-split equal power divider has been designed by using conventional 50 Ω microstrip line and double ended spur line renamed as defected microstrip structures (DMS). Introducing DMS provides one stop band characteristics, changes the effective inductance and capacitance of the line by increasing effective dielectric constant, reduces the phase velocity and supports slow-wave propagation. Thus, increases the effective line impedance of the microstrip line. Consequently, all passive and active components that are implemented using DMS have a miniaturized size compared to conventional components. In this paper one 3 dB or equal power divider has been designed at 1.6 GHz in the first step. Where, 100 Ω output line is implemented using double ended spur type DMS on conventional 50 Ω microstrip line. In the second step each output port power has been divided equally into 6 dB in the next level of the branch. Design of those dividers are very simple and have wide applications in microwave circuits and feeds of array antennas.

Compact UHF 3 dB MCCT Power Dividers

A compact UHF 3 dB power divider (PD) is presented. It consists of two identical asymmetric impedance transformers (MCCTs) and one isolation circuit with resistance and capacitance. The MCCT is composed of two different transmission-line sections and one open stub, and good frequency performance may be achieved by the combination of transmission-line sections and open stub. One PD is fabricated at a design center frequency of 500 MHz, of which total transmission-line sections are only 39.68° long. The measured bandwidth with 15 dB return loss is about 68%.

Dual-Resonant-Mode (DRM) Impedance Transformer and Its Application to Wideband 3 dB Power Divider

This work proposes a wideband impedance transformer through proper excitation of dual resonant modes (DRM) in a single resonator. Using an equivalent model that consists of two shunt resonant circuits in parallel, its working principle is physically explained and its wideband impedance transforming performance is achieved. Finally, a wideband 3 dB power divider is developed using this proposed transformer and the predicted results are well confirmed in experiment.

Y-junction power divider based on substrate integrated waveguide

The substrate integrated waveguide (SIW) plays a very important role in millimetre-wave and microwave integrated circuits and systems with low return loss and high Q-factor. Also, the half-mode substrate integrated waveguide (HMSIW) has been developed in recent years. A new Y-junction four-way power divider is proposed by integrating the 90° Y-junction SIW power divider and HMSIW power divider. Simulated and measured results show that the return loss of the input port is below −15 dB over 8.6 to 12.2 GHz and transmissions are about −7.6 dB±0.2 dB in the passband. So, it makes the 6 dB power divider used preferably in a broad bandwidth. The new power divider can be produced in batches and can be widely used in millimetre-wave and microwave circuits owing to its simple and novel structure.

Reduced Sideband Levels in Time-Modulated Arrays Using Half-Power Sub-Arraying Techniques

A new approach to reducing the sidebands levels and power losses in the harmonic patterns of time-modulated linear arrays is presented. The approach is based on reducing the static element weights of the outer elements of a linear array using simple 3 dB power dividers. This approach allows the relative switch-on times of the outer elements of the array to be increased which reduces the transients in the time-domain output from the array and results in lower sideband levels. Numerical results are presented to illustrate and compare the approach to conventional switching schemes.

A Novel Power Divider Based on Dual-Composite Right/Left Handed Transmission Line

A novel 3 dB power divider based on dual-composite right/left handed transmission line (D-CRLH TL) is proposed for the first time. The D-CRLH TLs are applied as artificial transmission lines. The wideband compact D-CRLH power divider is with low insertion loss and excellent amplitude and phase balance. The experimental results show that |S 11| is below −15 dB; the isolation is higher than 15 dB; and the insertion loss is less than 1 dB from 0.85 GHz to 4.3 GHz. The two output ports achieve the same amplitude and phase. The amplitude balance is below 0.3 dB, and the phase balance is less than 3°. The simulation results agree well with the measurements. The power divider has good application prospects in microwave systems.

Novel Compact Circularly Polarized Microstrip Antenna using Left-Handed Transmission Lines

A novel compact circularly polarized microstrip antenna using left-handed transmission lines is proposed in this paper. The antenna consists of a microstrip patch unit and two left-handed transmission line (LHTL) units. The microstrip patch unit is a square patch with a small square slot embedded in the center. The left-handed transmission line units located in the center of the square patch is composed of lumped elements, which work as 3 dB power dividers and 90 degrees phase shifters. The microstrip antenna is fed by a single probe, and the two inner adjacent sides of the square patch are connected to the LHTL units for orthogonal excitation. The measured results agree with simulated results, which show that the impedance bandwidth defined by VSWR less than 2.0 is 61 MHz (2481–2542 MHz). The front-to-back ratio on the pattern is larger than 15 dB and the axial ratio in the up hemisphere less than 2 dB. The proposed antenna has the attractive features such as compact size, low axial ratio, and simple structure.

Optimal discrete-amplitude excitations for arrays feeding a parabolic antenna . receiving from off-axis satellites

One relatively inexpensive setup for domestic reception of signals from two or more satellites is to use a conventional offset parabolic reflector fed by suitably placed off-axis arrays. In this paper, we show that the peak gain attainable using arrays with element-excitation amplitudes restricted to two or three values provided by a cascade of 3 dB power dividers can be as little as a few tenths of a decibel lower than that of arrays with unrestricted excitations. the optimum excitations are synthesized by a simulated annealing and downhill simplex optimization method.

Design and realisation of dual-band 3 dB power divider based on two-section transmission-line topology

A new dual-band 3 dB three-port power divider with arbitrary impedance terminations is proposed. The structure is composed of a two-section transmission-line transformer and an isolation resistor. Each transmission line's electrical length is π/3 at the fundamental frequency. Based on an ideal transmission line model, new design equations and graphs are given. The technique is validated by the experimental results on a 3 dB 900/1800 MHz power divider with ZS=100 Ω and ZL=50 Ω. Good performances of the proposed power combiner/divider at both frequencies are obtained.

Three-dimensional electromagnetic modeling of fiber-core effects on the coupling characteristics of weakly fused tapered fiber-optic couplers

Based on the full-wave formulations, which combine the finite element method add the boundary element technique, and the step-like approximation method, a three-dimensional (3-D) electromagnetic modeling approach is proposed in this work to investigate the fiber-core effects on the coupling characteristics of the weakly fused tapered couplers. We find the fiber cores have significant effects on the mode field patterns, coupling coefficients, and birefringence for the coupler with large normalized frequencies. The influence of the fiber cores on the coupling behavior for the real couplers, such as 3 dB power dividers, polarization beam splitters, and wavelength demultiplexing/multiplexing couplers, are also studied in 3-D view. It is found that the effects of fiber-cores in the weakly fused tapered couplers have to be considered for accurately modelling their coupling behavior, although the model with no core assumption can predict the trend of the coupling characteristics for the real couplers.

Low-loss Y-branch power dividers

Low-loss Y-branch 3 dB power dividers in Ti: LiNbO3 have been designed and tested. The symmetric output arms consist of S-bends. Numerous Y-branches were made exhibiting <0.25 dB excess loss for both the TE and TM polarisations. Histograms of the splitting ratio are also included, and demonstrate the excellent splitting ratios achieved.

Optimized E-Plane T-Junction Series Power Dividers

A rigorous design theory for compact rectangrdar waveguide power dividers with unsymmetrical series E-plane T-junctions of suitably optimized different waveguide heights and distances is described. The method is based on field expansion in normalized eigenmodes which yield directly the modal S-matrix of two appropriate key building blocks. The immediate modal S-matrix combination of the individual structures includes the effects of all step discontinuities and their mutual higher order mode interaction. Computer-optimized -3.01 dB, -4.77 dB, and -6.02 dB power divider examples achieve about +-0.25 dB coupling deviation at the output ports, together with about 30 dB return loss at the input port, for the chosen design frequencies of 12 GHz, 31.6 GHz, and 15.5 GHz. The -4.77 dB power divider provides a bandwidth of about 8 percent. The theory is verified by measurements.

High-order mode coupler for millimetre wavelengths

A new type of injection filter has been developed that can be used for local-oscillator injection in millimetre-wave mixers and other narrowband diplexing applications. The insertion loss for nonresonance frequencies is typically less than 0.25 dB. For the selected resonant modes, the coupler acts as a 3 dB power divider. Insertion losses of 1.5 dB or less can be reached at these frequencies.