Thin Microstrip Line Research Articles

Design process of a compact Tri-Band MIMO antenna with wideband characteristics for sub-6 GHz, Ku-band, and Millimeter-Wave applications

This article proposes a tri–band Multiple Input Multiple Output (MIMO) antenna operating at 5.2 – 5.7 GHz (5G Wi–Fi), 11.8 GHz – 17.3 GHz (Ku–band), and 23.4 GHz – 37.3 GHz (5G millimeter–Wave) frequency bands. The proposed MIMO antenna consists of a 2 × 2 configuration with a defective ground structure on Rogers–5880 substrate. An innovative passive decoupling structure, featuring thin microstrip lines positioned between the radiating elements, has been meticulously engineered to ensure a high level of isolation, achieving values of less than −20 dB. The peak gain of the MIMO antenna is found to be 3.05 dB, 5.27 dB, and 6.97 dB at 5.5 GHz, 17 GHz, and 35.5 GHz frequency bands, respectively. Measured ECC is less than 0.007, and DG is greater than 9.96. The radiation efficiency is above 90 %, TARC is less than –10 dB and channel capacity loss is below 0.4 Bits/s/Hz in all the bands of operation. The simulated and measured results are found to be in good agreement and the proposed MIMO antenna offers numerous advantages, including extensive frequency coverage, broad bandwidth, exceptional isolation, high gain, and efficiency. Consequently, it emerges as a promising choice for devices operating in Sub-6 GHz, Ku-band, and millimeter-wave applications.

Single-Feed Triple Band Microstrip Antenna for High Frequencies

This project presented a Design of a Single feed microstrip antenna has proposed for the Triple band operations and at the same time it mainly designed for satellite communication and the applications in K/Ka/Ku bands it is easy to fabricate, and high flexibility and improved antenna improved efficiency. The antenna has small dimensions of 70×29×0.787 and operates at 1GHz. This antenna mainly consists of a microstrip line in the center, two slot-loaded rectangular patches on the lateral sides, with two thin microstrip lines. The antenna is designed and simulated on High-Frequency Structure Simulator (HFSS) platform using Rogers RT/Duroid 5880 substrate with 0.787 dielectric constant and 0.002 loss tangent. The radiation pattern, return loss, vswr and gain results reveal that the antenna performs quite well at all frequencies.

A Singly-Fed Dual-Band Microstrip Antenna for Microwave and Millimeter-Wave Applications in 5G Wireless Communication

The coexistence of microwave (MW) and millimeter wave (MMW) technologies is considered as the development tendency of the future 5G wireless communication system. In this paper, a single-port, single-layer, dual-band antenna with large frequency ratio is proposed to support the MW and MMW applications. This antenna mainly consists of a stub-loaded microstrip line in the center, two slot-loaded rectangular patches on the lateral sides, and two thin microstrip lines in-between which connect the former two. The stub-loaded microstrip line works as a series-fed MMW linear array at 26 GHz, and simultaneously it serves as the feed line for the MW patches operating at 4.85 GHz. The connection lines are elaborately designed to isolate the MW patches from the MMW signal, guaranteeing the radiation performance of the antenna at the two bands without requiring complicated filter. For verification, a prototype is fabricated and measured. The measured results show that the antenna has an impedance bandwidth of 3.1% and a peak gain of 8.93 dBi at the 4.85-GHz MW band, while an impedance bandwidth of 19% and a peak gain of 13.57 dBi at the 26-GHz MMW band.

Reconfigurable Compact Wideband Circularly Polarised Dielectric Resonator Antenna for Wireless Applications

In this work, a novel compact wideband reconfigurable circularly polarised (CP) dielectric resonator antenna (DRA) is presented. The L-shaped Dielectric resonator antenna is excited by an inverted question mark shaped feed. This arrangement of feed-line helps to generate two orthogonal modes inside the DR, which makes the design circularly polarised. A thin micro-strip line placed on the defected ground plane not only helps to generate a wideband response but also assist in the positioning of the two diode switches. These switches located at the left and right of the micro-strip line helps in performing two switching operations. The novel compact design offers the reconfigurability between 2.9–3.8 GHz which can be used for different important wireless applications. For the switching operation I, the achieved impedance bandwidth is 24% while axial ratio bandwidth (ARBW) is 42%. For this switching state, the design has 100% CP performance. Similarly, the switching operation II achieves 60% impedance bandwidth and 58.88% ARBW with 76.36% CP performance. The proposed design has a maximum measured gain of 3.4 dBi and 93% radiation efficiency. The proposed design is novel in terms of compactness and performance parameters. The prototype is fabricated for the performance analysis which shows that the simulated and measured results are in close agreement.

A Balun Bandpass Filter to Facilitate the Design of Dual-Polarized Dipole Antenna

A dipole antenna based on a balun bandpass filter (BPF) is developed in this paper. The balun BPF employs two U-shaped resonators settled on the left side of the open-circuited transmission line and two L-shaped stubs to produce signals with equal amplitude and inverse phase. In this way, the volume of the balun BPF is reduced by half, and the distance between two output ports is dramatically decreased. Then, the balun BPF is integrated with a dipole. Instead of the traditional Γ-shaped line with a wide balun ground, two thin microstrip lines with width of 1 mm are adopted to connect the dipole and the balun BPF. The antenna bandwidth is further extended due to the fusion of the resonance of the dipole and balun BPF. As a result, the proposed antenna can operate from 4350 to 5025 MHz (covering the n79 band of 5G NR, 4400 MHz–5000 MHz), yielding a good filtering performance in the stopband. The measured half-power beamwidth is ranging from 61° to 63° and the measured gain is ranging from 7.95 to 8.5 dBi in the passband. This new balun BPF and the dual-polarized dipole based on it have great potential to be applied in 5G MIMO systems.

Microstrip BPFs with Increased Selectivity and Asymmetric Frequency Responses

Two symmetrical third-order microstrip bandpass filters (BPF) with all mixed coupling coefficients are proposed and analyzed. The first filter is a combline filter with stepped impedance resonators (SIR) closely spaced to each other. This leads to mixed couplings between adjacent resonators. The cross coupling of the end resonators is also mixed K13 = Km13 + Ke13 (MCC). Its magnetic component Km13 is due to a parasitic magnetic coupling between these resonators. To form the electric coupling component Ke13 a thin microstrip line segment was used that connects the resonators through the capacitive gaps. It was found that such a filter has two adjustable transmission zeros (TZ), which can be located both to the right and left of the central frequency f0 of the bandwidth. The second BPF differs from the first in that its central SIR is replaced by a half-wave through-type resonator, which is included in the filter as a two-port circuit. The used half-wave resonator has a U-shape and it works as the admittance inverter, in addition to the resonance phenomenon. This feature leads to a change in the frequency response of the filter. This filter has two adjustable TZs, which are located on both sides of the center frequency f0 of the bandwidth asymmetrically. The direct and inverse problems for the third-order BPF with all mixed couplings are also solved. The solution is based on the conductance matrix [Ỹ] and its minor M31. The direct problem solution makes it possible to determine the TZs of the filter using the given coupling coefficients. In the inverse problem, the filter’s coupling coefficients are determined by the specified TZs. The samples of two experimental filters and measuring frequency responses are presented.

Wideband Compact Triangle-Slot Antenna With Out-of-Band Rejection

A wideband and compact triangle-slot antenna with out-of-band rejection is proposed. The antenna covers the whole C-band (4–8 GHz) including the 5.8 GHz ISM and sub-6 GHz band of 5G. First, a right-angled triangle-slot antenna is developed from a rotated square-slot antenna with a 50% size miniaturization. Then, a defected ground slot (DGS) and a thin microstrip line section are integrated into the antenna to improve the out-of-band rejection. This prevents the noise and unwanted interference to the receiver and effectively suppresses the high-order harmonics from the transmitter. Importantly, the added DGS and thin microstrip line increases the bandwidth up to 5.51 GHz (82.7% fractional bandwidth) and reduces the antenna size. Finally, by adding matching elements using stacked rectangular slot principle, the antenna size is reduced furthermore, leading to a total 60% reduction in size. The final ground size is 32 × 32 mm, which is suitable to be integrated into portable devices. The return loss is measured up to the third harmonic of the highest working frequency and compared with the reference triangle-slot antenna to validate the rejection concept. The out-of-band return loss remains smaller than 1.2 dB up to 26.5 GHz. The maximum improvement of return loss is 33.3 dB at 26.4 GHz, from 34.4 dB of the reference antenna to 1.1 dB of the proposed antenna.

Design of a very compact U‐HI‐LO low‐pass filter using meander technique and quasi horn inductors for L‐band and C‐band applications

ABSTRACTIn this article, a novel very compact low pass filters, using Hi‐Lo technique and meander method are proposed. The several proposed filters are designed using a modification along the microstrip line by addition of U form and a meander shape. The compact meander LPF consists of two thin microstrip lines, which are connected with 50‐Ω microstrip feed lines and thus with the both SMA connectors and a width microstrip patch placed in the middle of the structure. This meander Hi‐Lo topology has been placed on the RO4003 substrate with a relative dielectric constant εr = 3.38 and thicknesses h = 0.813 mm and a loss tangent of 0.0027. Additionally to a very good compactness, the structure exhibits simple design and fabrication, very low insertion loss in the passband of 1.5 dB, and it achieves a wide rejection bandwidth with overall 20 dB attenuation from 5.7 to 6.3 GHz. The compact low pass structure occupies an area of (0.337 λg × 0.253 λg) where λg = 60 mm is the wavelength at the cut‐off frequency 2.75 GHz. The simulated and measured results show good agreement and validate the proposed approach. Such compact filter structures are used in various microwave system applications. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:2897–2901, 2016

Miniaturized C-Band SIW Filters Using High-Permittivity Ceramic Substrates

This paper introduces an effective way to build efficient miniature C-band filters using high-permittivity ceramics. The objective was to evaluate the feasibility of such filters using commercial electromagnetic simulators and a conventional fabrication process. For the demonstration, the substrate integrated waveguide (SIW) technology was chosen. Compared with planar solutions, this configuration offers good quality factors and good electrical performances as a consequence. However, its dimensions are large, leading to unacceptably large footprints for many applications. The solution proposed in this paper is based on a ceramic substrate with a permittivity of 90, which allowed us to work with shorter wavelengths. In comparison with a standard alumina substrate (permittivity $\varepsilon _{r}= 9.9$ ), this approach makes it possible to reduce the footprint up to nine times. Two prototypes were realized on a Trans-Tech ceramic substrate ( ${\rm thickness}=635~\mu \text{m}$ , $\varepsilon _{r} = 90$ , and tan $\delta = 9\cdot 10^{-4})$ . The first prototype is a folded sixth-order SIW filter including a cross coupling combining coplanar waveguide probes and a thin microstrip line on an InterVia substrate. The second one is a folded eighth-order SIW filter without cross couplings. Here, we compare the sixth-order prototype with an identical one built on alumina. The eighth-order filter, which had no alumina counterpart, is a potentially useful alternative for situations where complex technological steps must be avoided.

A trapezoidal microstrip patch antenna on photonic crystal substrate for high speed THz applications

Terahertz technology opened its wings toward the partially explored electromagnetic spectrum (30–10,000GHz). This paper presents a novel trapezoidal shape microstrip patch antenna for terahertz regime applications. A thin microstrip line is used to provide the coupling between source and antenna. The proposed antenna is developed to be utilized in the frequency band of 0.88–1.62THz for high speed applications. The performance of patch antenna is limited due to surface leaky waves beneath; therefore workability of the patch antenna is enhanced by employing photonic crystals in the thick dielectric substrate. It is observed that the return loss, VSWR and gain achieved show enormous improvement. The proposed antenna exhibits a wider bandwidth ranging between 1.2THz and 1.62THz.

RFID TAG ANTENNA FOR METALLIC OR NON-METALLIC SURFACES

A capacitively fed rectangular patch antenna for anti-metal RFID tag was studied. It was found that by using capacitively feeding and a thin micro-strip line, the input impedance could be stabilized with respect to ground plane size. As a result, the reading range degradation was avoided, and the presented antennas have almost the same reading range when used on metal or non-metal objects. The mechanism was explained by a basic antenna design and a transmission line model. Then a more practical compact design having much smaller size was presented. Prototypes of both the basic design and the compact design were fabricated and tested. The testing results validated the effectiveness of the designing method.

Integrated inductors on liquid crystal polymer substrate for RF applications

PurposeTo investigate the fabrication of integrated inductors on a liquid crystal polymer (LCP) substrate. To analyze the RF performance of the integrated inductors.Design/methodology/approachFabrication of integrated inductors on a LCP substrate using an MCM‐D/L technique. A lumped element model of the integrated inductors is proposed. An analytical approach is used to extract the parameters in the model.FindingsIntegrated inductors on a LCP substrate have been fabricated using an MCM‐D/L technique. The conductor loss of the thin microstrip lines is the major factor degrading the Q‐value of the integrated inductors. A lumped element model of the integrated inductor is proposed. The parameters of the lumped element model can be extracted from the geometry of the integrated inductor. Further work will focus on increasing the conductor thickness from 500 nm to 5 μm.Originality/valueThe value of the paper lies in its description of the integration of inductors on a LCP substrate. It also describes how to extract parameters of the lumped element model of the integrated inductors from the geometry.

Shape sensitivities of capacitances of planar conducting surfaces using the method of moments

In this contribution, a new method is presented to obtain the sensitivities of the capacitance or the charge with respect to a geometrical parameter of planar conducting surfaces. The charge density is found by an integral equation technique. By applying the flux-transport theorem, a new integral equation for the total derivative of the charge with respect to a geometrical parameter is derived from the original electrostatic integral equation for the charge distribution. This new integral equation is solved together with the original integral equation by the method of moments using the same set of basis and test functions. The method is also applied to obtain derivatives for the inductance, impedance and effective dielectric constant. Some simple electrostatic problems are presented, which illustrate the capabilities of our approach. In these examples we also discuss the difference between the geometrical derivatives obtained in this way with geometrical derivatives which are obtained by a central finite difference estimate. Next, some examples of the calculation of geometrical derivatives of capacitance and inductance matrices of multilayer, multiconductor thin microstrip lines are discussed.