Planar Transmission Lines Research Articles

Topological State in Heterostructured Gap Waveguides and Their Transitions to Classical Transmission Line

AbstractGap waveguides play a crucial role in millimeter‐wave information transmission and processing for next‐generation wireless communication and radar sensing systems. However, they suffer from challenges, such as reflection and scattering losses at sharp bends and defects. While topological photonic crystals offer innovative solutions for robust signal transmission, their localized interface states and unique electromagnetic modes pose compatibility challenges with practical circuits and systems. In this paper, a novel heterostructured gap waveguide support valley‐locked topological guided wave transport is introduced. This design ensures robust propagation against defects and bends while maintaining compatibility with classical transmission lines. Its topological characteristic reduce sensitivity to fabrication and assembly errors. More importantly, an efficient transition structure is developed to seamlessly convert quasi‐transverse electromagnetic (quasi‐TEM) modes in planar transmission lines to topological guided wave states, thereby effectively exciting topological waves. All theoretical predictions are quantitatively verified by the simulations and experiments at millimeter wave frequency. This heterostructured gap waveguide can find unique applications, such as power divider, as verified numerically. By leveraging topological principles, the proposed gap waveguide offers a significant performance boost for antennas and passive/active components in millimeter‐wave applications, including automotive radar, 5G communication, and synthetic‐aperture radar for imaging.

The Influence of the Skin Phenomenon on the Impedance of Thin Conductive Layers

This paper analyzes the influence of the skin effect and the proximity effect on the inductance and impedance of thin conductive layers. The motivation for taking up this topic is the initial assessment of the possibility of using conductive layers deposited with the PVD technique on textile materials as strip or planar transmission lines of high-frequency signals (e.g., for transmitting images). This work pursues two goals. The first of them is to develop and test a numerical procedure for calculating the electromagnetic field distribution in this type of issue, based on the fundamental solution method (FSM). The second aim is to examine the impact of the skin phenomenon on the resistance, inductance and impedance of thin conductive paths. The correctness and effectiveness of FSM for the analysis of harmonics of electromagnetic fields in systems containing thin conductive layers were confirmed. Based on the performed simulations, it was found that in the frequency range above 10 MHz, the dependence of resistance and impedance on frequency is a power function with an exponent independent of the path width. Moreover, it was found that for paths with a width at least several times greater than their thickness, the dependence of the phase shift between current and voltage on frequency practically does not depend on the path width.

Engineering planar antenna using geometry arrangements for wireless communications and satellite applications

A triple-band microstrip patch antenna designed for the IEEE 802.16e WiMAX, IEEE 802.11a WLAN, C-band downlink communications, and Ku-band radar recent applications is suggested in this article. The planned antenna operates at 2.45, 6, and 14 GHz resonant frequencies. The antenna fulfilled triple-band physical characteristics covering industrial, scientific, and medical (ISM) bands between (2.1–2.8) GHz; (5.6–6.5) GHz for wireless local area network (WLAN) or ultra-wideband (UWB) services; and 12.7–16 GHz for future two-way 5G:6G either broadcasting or mobile satellite communications. To achieve better return loss performance, parametric studies are carried out using Microwave Studio (CST MWS). The proposed antenna is designed on the FR4 as a hosting medium of total size 46 × 38 × 1.6 mm3, combined with a planar transmission line (T.L.) feed and defected ground structure (DGS). The simulated antenna’s input reflection coefficient (S11) results and the far-field measurements show good agreement. The fabricated prototype achieves peak gain values of 2.8, 3.8, and 4.7 dBi, respectively, and bidirectional radiation characteristics. A comparative study with other recent publications is implemented to validate the consistency of the design.

A kind of planar waveguides for cheating the high-speed digital signals into misidentifying the characteristic impedance

Since a planar periodic transmission line can suppress drastically the electromagnetic coupling, it would be advantageous to use such a kind of transmission lines in solving the problem of miniaturization of circuit area. By adjusting the lattice constants and geometric parameters of periodic microstrip lines, a time domain characteristic impedance that is the same as that of conventional microstrip lines (CMLs) can be achieved. Such periodic microstrip lines can therefore be used to trick high-speed digital signals, causing a digital signal to misjudge the time domain characteristic impedance of the transmission lines. The theoretical analysis has been verified by our experimental measurement results. Besides, a specific expression for the characteristic impedance of lossless periodic artificial materials is deduced by a circuit model and a standard of misidentification for the characteristic impedance of periodic microstrip lines is given for the digital signals.

Towards Monitoring and Identification of Red Palm Weevil Gender Using Microwave CSRR-Loaded TL Sensors.

This paper presents for the first time the design of a microwave sensing setup for the potential monitoring and identification of red palm weevil (RPW) gender type. The microwave sensor consists of a planar two-port transmission line (TL) with a single complementary split-ring resonant (CSRR) inclusion etched from the bottom metallic layer. The CSRR sensor is placed on top of a customized non-conductive container. The microwave sensing setup was designed, numerically demonstrated, fabricated and tested experimentally. Simulated results correlate quite well with the experimental data. Moreover, the sensitivity of the CSRR sensor when in close proximity to different RPW genders was evaluated both numerically and experimentally. Based on the measured results from 15 RPW samples with different body sizes, different RPW gender types showed unique microwave signatures. A notable shift in the sensor's resonance frequency was achieved, where on average a resonant frequency shift of 10% for adult RPWs was achieved, while a 2.4% frequency change was obtained for larvae (young) RPWs. Hence, the proposed microwave sensing setup can be adopted in field trials to examine and differentiate between various RPW genders at various developmental stages.

Investigation of Planar Isolators for Mutual Coupling Reduction in Two-Dimensional Microstrip Antenna Arrays

The design of isolators to reduce mutual coupling in large two-dimensional antenna arrays is complex and requires significant computational effort. This work attempts to alleviate this problem by applying different types of planar isolators in different orientations and experimenting first with two-element microstrip antenna arrays. A U-shaped planar transmission line isolator, a U-shaped planar transmission line-based destructive ground structure, and a planar neutralization line structure are designed to reduce E-plane or H-plane coupling in two-element microstrip antenna arrays. A mutual coupling reduction of approximately 6 dB is achieved. Four combinations of these planar isolators are compared and analyzed in a four-element microstrip antenna array. An optimal combination is then obtained by using two reversely placed U-shaped line isolators, which reduce the mutual coupling by more than 6.1 dB. The study is also extended to a 5 × 5 antenna array. Similar results of mutual coupling reduction are obtained. In addition to simulation, both two-element and 25-element microstrip antennas have been constructed and tested. The agreement of the simulation results with the measured results confirms the effectiveness of the decoupling structures.

Multi Frequency Controllable In-Band Suppressions in a Broad Bandwidth Microstrip Filter Design for 5G Wi-Fi and Satellite Communication Systems Utilizing a Quad-Mode Stub-Loaded Resonator

The key elements used for receiving and processing signals in communication systems are the bandpass filters. Initially, a common operating mechanism was applied for the design of broadband filters, i.e., by cascading low-pass filters or high-pass filters using multiple line resonators with length quarter-half- or full-wavelength with central frequency, but using these approaches, the design topology becomes expensive and complex. The above mechanisms can be possibly overcome using a planar microstrip transmission line structure due to its simple design fabrication procedure and low cost. So, pointing out the above problems in bandpass filters such as low-cost, low insertion loss, and good out-of-band performance, this article presents a broadband filter with multifrequency suppression capability at 4.9 GHz, 8.3 GHz, and 11.5 GHz using a T-shaped shorted stub-loaded resonator with a central square ring coupled to the basic broadband filter. Initially, the C-shaped resonator is utilized for the formation of a stopband at 8.3 GHz for a satellite communication system, and then a shorted square ring resonator is added to the existing C-shaped structure for the realization of two more stopbands at 4.9 GHz and 11.5 GHz for 5G (WLAN 802.11j) communication, respectively. The overall circuit area covered with the proposed filter is 0.52 λg × 0.32 λg (λg is the wavelength of the feed lines at frequency 4.9 GHz). All the loaded stubs are folded in order to save the circuit area, which is an important requirement of next-generation wireless communication systems. The proposed filter has been analyzed using a well-known transmission line theory, even–odd-mode, and simulated with the 3D software HFSS. After the parametric analysis, some attractive features were obtained, i.e., compact structure, simple planar topology, low insertion losses of 0.4 dB over the entire band, good return loss greater than 10 dB, and independently controlled mutli stopbands, which make the proposed design unique and can be used in various wireless communication system applications. Finally, a Rogers RO-4350 substrate is selected for the fabrication of the prototype using an LPKF S63 ProtoLaser machine and then measured using a ZNB20 vector network analyzer for matching the simulated and measured results. After testing the prototype, a good agreement was found between the results.

Fuzzy models for quasi‐static calculations of single ground plane coupled CPW by CADMFILT software

AbstractIn this paper, two new subdesign tools including the quasi‐static and fuzzy model calculations for the electrical parameters of the coupled planar transmission lines used in the design of microwave communication subsystems including resonators, filters, and multiplexers are presented for CADMFILT software. Proposed subdesign tools have properties such as electrical parameter calculations for microwave circuit analysis/synthesis, fuzzy logic model applications, comparisons, and graphical demonstrations. The first subdesign tool can calculate the electrical parameters of the coupled planar transmission lines by using the quasi‐static analysis method. The other tool is based on subtractive fuzzy clustering, which can offer approximate solutions as an alternative to numerical and analytical closed‐form expressions of quasi‐static analysis. The proposed subdesign tools have a competent and efficient algorithm to provide fast, accurate, and sensitive results. To test the accuracy of these tools, a coupled coplanar waveguide with a single ground plane structure has been performed. The results obtained from the subdesign tools for both approaches have been compared. The proposed fuzzy logic models use the electrical parameters calculated from the quasi‐static analysis as training and control data files. The accuracy of each model has been tested by error analysis and the validity of the model results has been demonstrated by comparing them with the results of the quasi‐static approach. It is expected that the developed efficient, fast, and versatile subdesign tools will help researchers to simplify their designs by providing a control mechanism in the RF/microwave circuit design processes.

MICROWAVE SENSOR BASED ON MEANDER-SHAPED VOLUMETRIC STRIP LINE FOR DIELECTRIC CONTROL OF LIQUID MEDIA

The paper proposes a new type of transducer elements for means of dielectric control of liquid media operating in the long-wave region of the microwave range, based on meander-shaped volumetric strip lines. Their main difference is the increased conversion sensitivity and smaller linear dimensions in comparison with sensors based on planar transmission lines. The introduction describes the relevance of the problem being solved, raises the problem of the need to increase the size of the transducer elements in the frequency range under consideration to ensure satisfactory sensitivity, and determines the transition to bulk structures. In the main part of this section, a mathematical description of the elementary cells of a volumetric strip microwave structure is carried out, and a comparison of the sensitivity with microstrip lines with a dielectric coating that are equivalent in physical parameters is given. In the experimental part of the article, the proposed structure is tested as a transducer element in a experiment to assess the degree of water cut in oil. The result of the experimental study is the obtained sensitivity value of the developed sensor S = 3.142 deg/%, as well as an estimate of the error in measuring the oil water cut, which amounted to 0.3 %.

Gap Waveguide Technology: An Overview of Millimeter-Wave Circuits Based on Gap Waveguide Technology Using Different Fabrication Technologies

With the fast development of next-generation wireless communication and radar sensing, the millimeter-wave frequency band is becoming more and more important due to its rich spectrum, wide bandwidth, and ability to support the miniaturization of antennas and circuits <xref ref-type="bibr" rid="ref1" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">[1]</xref> , <xref ref-type="bibr" rid="ref2" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">[2]</xref> , <xref ref-type="bibr" rid="ref3" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">[3]</xref> , <xref ref-type="bibr" rid="ref4" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">[4]</xref> . High-performance, low-loss, and low-cost millimeter-wave circuits and modules are the key elements for wireless front-end systems. For planar transmission lines, such as microstrip lines and coplanar waveguides, they are very easy to integrate with other circuits for low-cost and low-profile physical designs. However, the high insertion loss and radiation loss from planar transmission lines limit their applications at the millimeter-waveband. As for rectangular and cylindrical waveguides, their main application is in the areas of low loss and high power handling, but their 3D structure is difficult to integrate with other planar passive and active circuits. The substrate-integrated waveguide (SIW) is a better way to merge the advantages of planar transmission lines and rectangular waveguides, but it still suffers from dielectric losses at the millimeter-wave frequency range.

Contactless RF Probe Interconnect Technology Enabling Broadband Testing to the Terahertz Range

Radiofrequency (RF) probes based on 50- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\Omega$</tex-math></inline-formula> planar transmission lines play a key role in almost every stage of RF device development, establishing the physical contact between high-end instrumentation and the device. With the continuous downscaling of semiconductor technologies to reach into the millimeter-wave (30–300 GHz) and Terahertz (300 GHz to 3 THz) bands and devices exhibiting broader frequency response, current RF probe technology is the Achilles heel for precise and repeatable measurements. Here, we propose a novel RF probe technology based on the near-field coupling of single-mode dielectric waveguide structures, which according to our full-wave simulations provide an extremely broad frequency range covering from 0 Hz up to 340 GHz, the largest continuous bandwidth reported to date. A concept demonstrator using this approach shows contactless RF probing on test structures, which shows the path toward continuous measurements across the microwave, millimeter-wave, and Terahertz range.

Characterization of Transmission Lines on Lossy or Dispersive Substrates With a Complete Model of a Series Resistor for Impedance Standard of Scattering Parameter Measurements

This paper presents a complete model and process for obtaining a solution for a series resistor with frequency-dependent resistance and inductance to characterize planar transmission lines (TLs) after a one-tier multiline thru-reflect-line (TRL) calibration. The impedance of TL characterization actually is the reference impedance of scattering parameter (S-parameter) measurements and is not easy to determine for TLs on lossy or dispersive substrates. To account for parasitic effects at high frequencies, the series resistor is modeled as a lossy TL segment with a frequency-dependent resistance and inductance per unit length with additional discontinuities between the TL and the resistor. The TL characteristic impedance can then be evaluated based on the de-embedded S-parameters of series resistors with lengths <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">l_s</i> and 2 <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">l_s</i> after calibration, in which the TL propagation constant is determined as well to complete the TL characterization. The proposed method is examined by using coplanar waveguides (CPWs) fabricated with an integrated passive device (IPD) process on high-resistivity silicon and fabricated with standard CMOS technology to demonstrate the frequency dependence of the resistance of the series resistors at high frequencies. Independent calibration comparison measurements are conducted to validate the acquired TL characteristic impedances up to 110 GHz.

Parametric Amplification via Superconducting Contacts in a Ka Band Niobium Pillbox Cavity

Superconducting parametric amplifiers are commonly fabricated using planar transmission lines with a nonlinear inductance provided by either Josephson junctions or the intrinsic kinetic inductance of the thin film. However, Banys et al. (J Low Temp Phys, 2020) reported nonlinear behaviour in a niobium pillbox cavity, hypothesising that below T_c, the pair iris-bulk resonator would act as a superconducting contact surface exploiting a Josephson-like nonlinearity. This work investigates this effect further by applying Keysight Technologies’ Advanced Design System (ADS) to simulate the cavity using an equivalent circuit model that includes a user defined Josephson inductance component. The simulations show that for a resonance centred at nu _0=30.649 GHz, when two tones (pump and signal) are injected into the cavity, mixing and parametric gain occur. The maximum achievable gain is explored when the resonator is taken to its bifurcation energy. These results are compared to cryogenic measurements where the pump and the signal are provided by a Vector Network Analyzer.

Characterization of Alumina Ribbon Ceramic Substrates for 5G and mm-Wave Applications

A recently developed material technology at Corning Inc., namely, Alumina Ribbon Ceramic (ARC), is investigated as a potential substrate candidate for fifth generation (5G) and millimeter-wave (mm-wave) applications. In this article, we characterize an 80- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{m}$ </tex-math></inline-formula> -thick ARC substrate material in the frequency range of 3–50 GHz using microstrip ring resonator (MRR) method and extract the loss of various planar transmission lines, such as microstrip and coplanar waveguide (CPW) lines on ARC substrate up to 50 GHz as well. Moreover, different test structures designed on an 80- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{m}$ </tex-math></inline-formula> -thick ARC substrate are utilized to extract the electrical parasitics associated with a single-grounded through-alumina via (TAV) and transmission properties of ground–signal–ground (GSG) TAV of 40 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{m}$ </tex-math></inline-formula> diameter over the frequency range of 0.1–50 GHz. The semiadditive patterning (SAP) process is employed to metallize the top and bottom layers of ARC substrate to form the copper traces for the designed structures. Combined with the previous characterization results of a 40- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{m}$ </tex-math></inline-formula> -thick ARC substrate in 30–170 GHz, the dielectric constant of ARC was extracted to be ~10.12 over 3–170 GHz, while its loss tangent varies in the range of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$6.6\times 10^{-5}-1.3\times 10^{-3}$ </tex-math></inline-formula> over the same frequency band. The average measured insertion loss of CPW lines varied from 0.026 to 0.24 dB/mm over 3–170 GHz. For the microstrip lines, the average measured insertion loss over the same frequency range was extracted to be between 0.019 and 0.293 dB/mm. Furthermore, the parasitic inductance and resistance of a single-grounded TAV are extracted to be 24.41 pH and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.987~\Omega $ </tex-math></inline-formula> , respectively, at 50 GHz, and the insertion loss per a GSG-TAV extracted from CPW-TAV daisy chain measurements is found to be 0.056 dB at 50 GHz as well. In addition to an excellent performance of ARC-based interconnects, the TAV in ARC is shown to have lower transmission loss up to 50 GHz, while exhibiting low parasitics.

Stripline Multilayer Devices Based on Complementary Split Ring Resonators.

A new analytic design for multilayer stripline devices in planar circuit technology is presented. The Complementary Split Ring Resonator (CSRR) is used as a sub-wavelength resonant particle, which provides high-Q resonances in a compact size. The electromagnetic field distribution achieved along the stripline enables enhanced excitation of the resonators. An optimal solution for multilayer power dividers is presented, in a configuration in which each output is obtained in different layers and also in a different layer than the input line. The solution is expanded to design different devices, such as diplexers, resonators, and multi-frequency resonators, leading to vertical filters. As the resonances are achieved by stacking resonators, the effective circuit footprint is very compact. The proposed devices can be implemented in a volumetric chip fashion, allowing integration with planar transmission line circuits and flexible output connection placement. A complete analysis of the different devices is proposed, extracting and verifying their equivalent circuit models.

A Novel End-Wall Waveguide Excitation With Wide Bandwidth and Simple Structure for Millimeter-Wave/Terahertz Application

In millimeter-wave (MMW)/terahertz (THz) band, the insertion loss of interconnection between waveguide and planar transmission lines is usually high, and the microassembly process is complex. In this letter, a novel broadband end-wall waveguide electromagnetic wave mode excitation is proposed for MMW/THz application. A simple circular open-circuit stub is utilized to transform the quasi-TEM mode of grounded coplanar waveguide (GCPW) to the dominant TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">10</sub> mode of rectangular waveguide (RWG). The operating frequency band can be adjusted and improved by controlling the positions of the matching via hole adjacent to RWG port. To further increase the excitation bandwidth, a U-shaped iris (U-iris) on the other side of the substrate is introduced and embedded in the end wall of the RWG to generate dual resonant excitation modes. A 0.2-THz transition from GCPW to RWG is designed as an example. Three back-to-back prototypes with different lengths are fabricated and measured. The measured return loss of single transition is better than 13 dB with an insertion loss of 0.8 ± 0.15 dB in the frequency range of 185–229 GHz (21.2% bandwidth). The proposed end-wall transition has the advantages of high efficiency, easy fabrication, and wideband performance.

Study of Dependence of Capacitance of Coupled Stripline on Stripwidth, Frequency and Spacing Between Two Striplines

In this present paper, we studied about the dependance of capacitance of coupled stripline on strip width, frequency and spacing between two striplines. Miniaturized microwave circuits fabricated by extension of integrated circuits (ICs) technology to microwave frequencies are known as Microwave Integrated Circuits (MICs). MICs promise a real revolution leading to both expansion of present markets of microwaves &amp; opening of many new applications including host of non-military uses in India &amp; abroad. With the advent of MICs planar Transmission Lines have been developed which have been proved to be very significant as regards the fabrication of various microwave-components such as: Directional Coupler, Filters, Isolator &amp; Impedance transformers etc. The planar Transmission Lines are: Stripline, Microstripline, Slot line, Coplanar Striplines &amp; their different variant forms such as inverted and suspended striplines &amp; microstriplines etc. Among these microstripline is the most suited due to its open structure, low losses in gigaharz range of frequency, reduced size, improved reliability and eventual cost reduction in mass production. The microstrip transmission line consists of a narrow strip conductor separated from a conducting ground plane by an intervening supporting dielectric substrate as studied by Wheeler and others. The electromagnetic traveling through such structures suffers from some losses like: Conductor loss &amp; Dielectric loss. There is a change of phase of the wave traveling through the structure also. This phase change (shift) depends on the width of metal strip, height of the dielectric substrate, permittivity of the substrate and operating frequency. The present study is devoted to this objective i.e. we have to study the variation of Phase-Shift of the wave within the structure with width of the stripline, height &amp; effective permittivity of the structure &amp; frequency.

A Review on SIW and Its Applications to Microwave Components

Substrate-integrated waveguide (SIW) is a modern day (21st century) transmission line that has recently been developed. This technology has introduced new possibilities to the design of efficient circuits and components operating in the radio frequency (RF) and microwave frequency spectrum. Microstrip components are very good for low frequency applications but are ineffective at extreme frequencies, and involve rigorous fabrication concessions in the implementation of RF, microwave, and millimeter-wave components. This is due to wavelengths being short at higher frequencies. Waveguide devices, on the other hand, are ideal for higher frequency systems, but are very costly, hard to fabricate, and challenging to integrate with planar components in the neighborhood. SIW connects the gap that existed between conventional air-filled rectangular waveguide and planar transmission line technologies including the microstrip. This study explores the current advancements and new opportunities in SIW implementation of RF and microwave devices including filters, multiplexers (diplexers and triplexers), power dividers/combiners, antennas, and sensors for modern communication systems.

Miniaturization of microwave planar circuits using composite microstrip/coplanar-waveguide transmission lines

The rapid development of modern communication systems propels the demand of high performance and miniaturization of RF/microwave components. Power dividers and filters are indispensable circuit components in amplifiers and antenna feed-networks which occupy large footprint of circuit broads, particularly at low frequency. The purpose of this study is to initiate a new type of planar transmission line with unique dual signal-path characteristics and ultimately achieve circuit miniaturization. In this paper, a novel technique of consolidating microstrip lines (MLs) and coplanar waveguide (CPW) lines on a single dielectric substrate, designated as the composite microstrip/CPW line (CM/CPW line), is proposed. With reference to the average line length of ML and CPW, it warrants a physical length reduction of 48.3% and further achieves a reduction of 80.8% after zigzagging CM/CPW line. The proof-of-concept design example of a two-way Wilkinson power divider (WPD) has demonstrated the effectiveness of the miniaturization technique. The simulation, in combination with the experimental results, validates that a size reduction factor of 86.9% when compared to conventional one has been achieved while maintaining a fractional bandwidth of 57.7% for the WPD.

Versatility of Laser Enhanced Direct Print Additive Manufacturing

This paper provides examples of the use of direct print additive manufacturing to fabricate RF/microwave and optical components. Direct print additive manufacturing is the combination of extrusion and micro-dispensing on a single tool. The design, 3D printing process and material selections for finite ground coplanar waveguide (FG-CPW) planar transmission lines, the integration of DC contact RF MEMS switches within the FG-CPWs, and optical interconnects are detailed. Picosecondpulsed laser machining is performed to enhance the finish quality of the devices and achieve minimum feature size down to 6 μm specifically for the RF switch.