Broadside-coupled Striplines Research Articles

A Compact Broadside Coupled Stripline 2-D Beamforming Network and Its Application to a 2-D Beam Scanning Array Antenna Using Panasonic Megtron 6 Substrate.

This article presents a 4-way 2-D butler matrix (BM)-based beamforming network (BFN) using a multilayer substrate broadside coupled stripline (BCS). To achieve the characteristics of a compact, wide-bandwidth, high-gain phased array, a BCS coupler is implemented using the Megtron 6 substrate. The compact 2-D BFN is formed by combining planarly two horizontal BCS couplers and two vertical BCS couplers. The BFN is proposed without a crossover and without a phase shifter, generating phase responses of ±90° in the x- and y-directions, respectively. The proposed BFN exhibits a wide operating band of 66.7% (3-7 GHz) and a compact physical area of just 0.25 λ0 × 0.25 λ0 × 0.04 λ0. The planar 2-D BFN is easily integrated with the patch antenna radiation elements to construct a 2-D multibeam array antenna that generates four fixed beams, one in each quadrant, at an elevation angle of 30° from the broadside to the array axis when the element separation is 0.6 λ0. The physical area of the 2-D multibeam array antenna is just 0.8 λ0 × 0.8 λ0 × 0.04 λ0. The prototypes of the BCS coupler, the 2-D BFN, and the 2-D multibeam array antenna were fabricated and measured. The measured and simulated results were in good agreement. A gain of 9.1 to 9.9 dBi was measured.

1-D and 2-D Beam Steering Arrays Antennas Fed by a Compact Beamforming Network for Millimeter-Wave Communication

In this article, a new Beamforming Network (BFN) realized in Broadside Coupled Stripline (BCS) is proposed to feed 1 × 4 and 2 × 2 arrays antenna at 28 GHZ-Band. The new BFN is composed only of couplers and phase shifters. It doesn't require any crossover compared to the conventional Butler Matrix (BM) which requires two crossovers. The tight coupling and low loss characteristics of the BCS allow a design of a compact and wideband BFN. The new BFN produces the phase differences of (±90°) and (±45°, ±135°) respectively in x- and y-directions. Its integration with a 1 × 4 linear array antenna reduces the array area by 70% with an improvement of the gain performance compared with the conventional array. The integration with a 2 × 2 array allows the realization of a full 2-D beam scanning. The proposed concept has been verified experimentally by measuring the fabricated prototypes of the BFN, the 1-D and 2-D patch arrays antennas. The measured 11.5 dBi and 11.3 dBi maximum gains are realized in θ0 =14° and (θ0, ϕ0)=(45°,345°) directions respectively for the 1-D and 2-D patch arrays. The physical area of the fabricated BFN is only (0.37λ0 × 0.3λ0 × 0.08λ0), while the 1-D array and 2-D array antennas areas without feeding transmission lines are respectively (0.5λ0 × 2.15λ0 × 0.08λ0) and (0.9λ0 × 0.8λ0 × 0.08λ0).

A 2-D Beam Scanning Array Antenna Fed by a Compact 16-Way 2-D Beamforming Network in Broadside Coupled Stripline

A 2-D beam scanning array antenna fed by a compact 16-way 2-D beamforming network (BFN) designed in Broadside Coupled Stripline (BCS) is addressed. The proposed 16-way 2-D BFN is formed by interconnecting two groups of 4x4 Butler Matrix (BM). Each group is composed of four compact 4x4 BMs. The critical point of the design is to propose a simple and compact 4x4 BM without crossover in BCS to achieve a better transmission coefficient of the 16-way 2-D BFN with reduced size of merely 0.8λ0 × 0.8λ0 × 0.04λ0. Moreover, the complexity of the interface connection between the 2-D BFN and the 4x4 patch array antenna is reduced by using probe feeding. The 16-way 2-D BFN is able to produce the phase shift of ±45°, and ±135° in x- and y- directions. The 2-D BFN is easily integrated under the 4x4 patch array to form a 2-D phased array capable of switching 16 beams in both elevation and azimuth directions. The area of the proposed 2-D beam scanning array antenna module has been significantly reduced to 2λ0 × 2λ0 × 0.04λ0. A prototype operating in the frequency range of 4-6GHz is fabricated and measured to validate the concept. The measurement results agree well with the simulations.

A W-Band Balanced Power Amplifier Using Broadside Coupled Strip-Line Coupler in SiGe BiCMOS 0.13-<inline-formula> <tex-math notation="LaTeX">$\mu\text{m}$ </tex-math> </inline-formula> Technology

Load-variation insensitivity, for impedance matching between power amplifiers (PAs) and transmitting antennas, contributes to challenging the design of millimeter-wave wireless systems. In this paper, a $W$ -band two-way balanced PA based on a compact quadrature coupler with a broadside coupled strip-line (BCSL) as the core is presented to enhance the load-variation insensitivity and stability. The proposed coupler is truly broadband with low amplitude and phase imbalance. The proposed $W$ -band balanced PA achieves higher power-added efficiency (PAE) and unsaturated output power ${P} _{\mathrm{ sat}}$ over wide frequency bandwidth. The $W$ -band balanced PA is implemented in a 0.13- $\mu \text{m}$ SiGe BiCMOS process and achieves a measured ${P} _{\mathrm{ sat}}$ of 16.3 dBm and a peak PAE of 14.1% at 100 GHz (with 1.6-V power supply). The measured ${P} _{\mathrm{ sat}}$ with 1-dB bandwidth is from 91 to 102 GHz. The measured results present the feasibility of the compact quadrature coupler. The total chip surface area (with pads) is 0.64 mm2, where the size of the proposed quadrature coupler area is only 0.04 mm2.

Design and Assembly of SPT-3G Cold Readout Hardware

The third-generation upgrade to the receiver on the South Pole Telescope, SPT-3G, was installed at the South Pole during the 2016–2017 austral summer to measure the polarization of the cosmic microwave background. Increasing the number of detectors by a factor of 10 to ∼16,000 ∼16,000 required the multiplexing factor to increase to 68 and the bandwidth of the frequency-division readout electronics to span 1.6–5.2 MHz. This increase necessitates low-thermal conductance, low-inductance cryogenic wiring. Our cold readout system consists of planar thin-film aluminum inductive–capacitive resonators, wired in series with the detectors, summed together, and connected to 4K SQUIDs by 10−μm 10−μm -thick niobium–titanium (NbTi) broadside-coupled striplines. Here, we present an overview of the cold readout electronics for SPT-3G, including assembly details and characterization of electrical and thermal properties of the system. We report, for the NbTi striplines, values of R≤10 −4 Ω R≤10−4Ω , L=21±1 nH L=21±1 nH , and C=1.47±.02 nF C=1.47±.02 nF . Additionally, the striplines’ thermal conductivity is described by kA=6.0±0.3 T 0.92±0.04 μW mm K −1 kA=6.0±0.3 T0.92±0.04 μW mm K−1 . Finally, we provide projections for cross talk induced by parasitic impedances from the stripline and find that the median value of percentage cross talk from leakage current is 0.22 and 0.09% 0.09% from wiring impedance.

Design and study of enhanced wideband transition between coplanar waveguide and broadside coupled stripline

Enhanced wideband transition between coplanar waveguide (CPW) and broadside coupled stripline (BCS) with arbitrary characteristic impedance ratio is developed on a basis of an improved tightly coupling, via-hole-free structure. The E-field of CPW gradually changes to that of BCS within a wide bandwidth with ratio up to 10.4:1. Parametric studies of the transition are carried out and four different back-to-back prototypes are simulated, fabricated and measured. It is shown that maximum operation bandwidth from 1.16 to 12.01 GHz for return loss higher than 10 dB and average insertion loss of 1.41 dB can be obtained.

Electrostatic Solution for Broadside-Coupled Striplines in a Shield

The electrostatic characteristics of broadside-coupled striplines in a shield are investigated with the mode-matching method. The Fourier series is employed to describe electrostatic potential distributions. Numerical results are shown for coupled transmission line cell applications.

A Broadband Transition Design for a Conductor-Backed Coplanar Waveguide and a Broadside Coupled Stripline

A broadband transition design between broadside coupled stripline (BCS) and conductor-backed coplanar waveguide (CBCPW) is proposed and studied. The E-field of CBCPW is designed to be gradually changed to that of BCS via a simple linear tapered structure. Two back-to-back transitions are simulated, fabricated and measured. It is reported that maximum insertion loss of 2.3 dB, return loss of higher than 10 dB and group delay flatness of about 0.14 ns are obtained from 50 MHz to 20 GHz.

Wideband coplanar waveguide to edges-even broadside-coupled stripline transition

A wideband transition between a coplanar waveguide (CPW) and an edges-even broadside-coupled stripline (EEBCS) is proposed. The simple transition is composed of a linear tapered line on the top layer and an electromagnetically-coupled Y-shaped stub on the bottom layer. A back-to-back, 50 Ω CPW to 100 Ω EEBCS transition is simulated, fabricated and measured. It is reported that a maximum insertion loss of 2.4 dB, a return loss better than −10 dB and average group delay of about 0.5 ns are obtained from 1.1 to 11.2 GHz for the transition.

Higher-order modes for broadside-coupled striplines in a shield

[1] A mode-matching method is applied to broadside-coupled striplines in a shield to obtain a dispersion relation. Higher-order mode analyses are performed, and their cutoff frequencies are evaluated. Good agreement with existing solutions is demonstrated. Higher-order field characteristics are illustrated. The mode-matching model provides an efficient and stable means of analyzing broadside-coupled striplines in a shield.

A Wideband Compact Planar Balun for UHF DTV Applications

In this paper, a wideband compact planar balun with impedance-transforming ratio of 2 : 1 is developed for push pull applications. The proposed balun is composed of broadside coupled strip lines and lumped capacitors. In this design, by utilizing broadside coupled strip lines with large enough spacing between strip and ground plane, even mode impedance of the transmission line and bandwidth is increased. Size reduction is effectively obtained by the use of discrete capacitors. As an example, one balun on a double-sided PCB is designed, simulated, fabricated and measured. Measured results show that the return loss is better than 15 dB over the frequency band from 470 MHz to 860 MHz, or around 59% bandwidth. The amplitude and phase imbalance between the two balanced output ports at worth case are 0.7 dB and 6 degree, respectively, over the operating frequency band.

Optimized Design of a Broadside-Coupled Suspended Stripline Filter

Optimized Design of a Broadside-Coupled Suspended Stripline Filter

A Dual-Band Balun Using Broadside-Coupled Coplanar Striplines

In this paper, a dual-band balun is presented. Based on the traditional Marchand balun configuration, this device utilizes a pair of lambda4 coupled-line sections and a single lambda4 open-circuit stub to achieve a dual-band balun-type function. An experimental prototype, operating at both 2.4- and 5.8-GHz bands, has been realized on a traditional printed circuit board using the broadside-coupled asymmetric coplanar stripline technique. Experimental measurements show good agreement with full-wave computer simulations, showing good potentials for dual-band/multiband RF front-end modules.

A 40-50-GHz SiGe 1 : 8 differential power divider using shielded broadside-coupled striplines

This paper presents a 1 : 8 differential power divider implemented in a commercial SiGe BiCMOS process using fully shielded broadside-coupled striplines integrated vertically in the silicon interconnect stackup. The 1 : 8 power divider is only 1.12 x1.5 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> including pads, and shows 0.4-dB rms gain imbalance and <3deg rms phase imbalance from 40 to 50 GHz over all eight channels, a measured power gain of 14.9 plusmn0.6 dB versus a passive divider at 45 GHz, and a 3-dB bandwidth from 37 to 52 GHz. A detailed characterization of the shielded broadside-coupled striplines is presented and agrees well with simulations. These compact lines can be used for a variety of applications in SiGe/CMOS millimeter-wave circuits, including differential signal distribution, miniature power dividers, matching networks, filters, couplers, and baluns.

On the design model of broadside-coupled SSS line for microwave integrated circuits

A practical design model for the analysis of broadside-coupled suspended-substrate stripline is presented. The modified design expression of the shielded microstrip line is valid for a wide range of structural parameters and dielectric constants, that is, 1.0 ≤ er ≤ 140.0 for dielectric constant, 0.1 ≤ w/h ≤ 10.0 for strip width with an accuracy of <0.5%. This design expression is further extended for broadside-coupled suspended-substrate stripline. The proposed broadside-coupled suspended-substrate stripline (BCSSS) expressions are valid over a practical range of structural parameters and dielectric constants. The validity range of this expression for structural parameters is 1.0 ≤ er ≤ 16.0 for dielectric constant, 0.1 ≤ w/b ≤ 2.0 for strip width, and s/b ≤ 0.5 for substrate thickness. The average accuracy of the present expressions is <0.6% and <0.2% for the even- and odd-mode effective dielectric constants, respectively, with maximum deviation less than 1.16% with respect to reference value. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 46: 292–297, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20969

Analysis and design of broadside-coupled striplines-fed bow-tie antennas

The design of a bow-tie antenna fed by broadside-coupled striplines (BCS) for the 2.4-GHz ISM band is described. The two fins of the bow tie are, respectively, on the two sides of the substrate. The feeding balanced lines adopted are the BCS. A quarter-wave transformer is used to transform the microstrip line input to the BCS feed. An analysis method based on the mixed-potential integral equation method is used to characterize the input characteristics of the bow-tie antenna. The numerical results obtained are in good agreement with the experimental data. Through experiments with bow-tie antennas of various extended angles, the bow-tie antenna with a 90/spl deg/ extended angle exhibits the widest bandwidth in the desired frequency band, which has a bandwidth of 19% for a VSWR<1.5:1.

Cad for analysis and synthesis of MM-wave transmission lines

This work presents a software for analysis and synthesis of four types of planar lines used on the millimeter wave band: Suspended Microstrip Line, Inverted Microstrip Line, Suspended Stripline and Broadside Coupled Stripline. Conceived for IBM/PG or compatible microcomputers, the program, (MMWL), can study each configuration at a time or all of them at once, and it does not matter if it is synthesis or analysis for each line at the same time. The results are presented in Tables shown in the same screen. The program also provides curves of characteristic impedances against conducting strip width for each one of studied structures. Therefore, it allows choosing the best combination for circuit realization, becoming a helpful tool for projects and with acceptable results.

Computer-aided design models for broadside-coupled striplines and millimeter-wave suspended substrate microstrip lines

Models were derived from the results of conformal transformation on homogeneous stripline, the equivalence of the odd-mode with the quasi-TEM mode of covered microstrip line, and logarithmic regression of spectral-domain results. Effects of finite strip thickness have been taken into account. These models are fully compatible with the needs and trends of computer-aided and programmable-calculator-aided microwave and millimeter-wave integrated circuit design.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Analysis of Some Planar Structures by the Least-Squares Boundary Residual Method

A new approach is proposed to analyze a large class of planar transmission lines such as shielded edge or broadside-coupled striplines and microslots with or without a ground plane. Calculations are carried out, in quasi-TEM and hybrid modes, by the application of a new variant of the least-squares boundary residual method (LSBRM), which is the basis change that allows one not only to improve the precision but also to reduce the computer memory occupation so that smaller computers can be used.

Dispersion characteristics of unsymmetrical broadside-coupled striplines with anisotropic substrate

Dispersion characteristics of the unsymmetrical broadside-coupled striplines of unequal width are presented for the first time. The frequency-dependent hybrid-mode solutions converge to the quasistatic values at lower frequencies for various structural parameters of the broadside-coupled suspended striplines (BCSSs) and broadside-coupled inverted striplines (BCISs) with the anisotropic substrates.