T-shaped Slot Research Articles

Differentially Fed Dual-Mode Patch Antenna With Wideband Common-Mode Absorption and Its Array Application

A differentially fed dual-mode patch antenna is proposed with wideband common-mode (CM) absorption. The proposed antenna consists of a differential feeding network, common ground plane, and the radiation patch with stepped widths. The differential feeding network is formed by adding an absorptive stub at the symmetric plane of balanced microstrip structure to achieve wideband CM absorption. Besides, a T-shaped slot is etched on the ground plane to realize aperture coupling to excite the radiation under TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">01</sub> and TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sub> modes. Subsequently, the differential parallel feeding technique is employed to design a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2 \times 4$ </tex-math></inline-formula> planar array with low cross polarization. As demonstration, the prototypes of the designed differential antenna and array are fabricated and measured. The measured results show that the proposed antenna element and array exhibit the broadened −10 dB impedance bandwidths covering the frequency range of 4.8–4.99 GHz, wide CM absorption band with about 70% fractional bandwidth, and low cross polarization below −20 dB. Furthermore, the measured peak realized gains of antenna and planar array are 7.5, and 16.6 dBi, respectively.

Switchable T-Slot for Dual-Circularly-Polarized Slot-Array Antennas in Ka-Band

This letter presents two slotted array antennas working in the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Ka</i> -band with switchable circular polarization capability. The first prototype is a series-fed slotted-waveguide linear array composed of ten T-shaped slots. The second antenna is a 2-D array with 2 × 2 T-shaped slots fed by a corporate distribution network. In both cases, a reflection coefficient below <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$-$</tex-math></inline-formula> 10 dB has been experimentally observed within the targeted frequency band between 29.5 and 30.5 GHz. Good polarization purity is achieved for both polarization senses and in both prototypes. The fundamental contribution of this letter is to propose a simple mechanism to switch the circular polarization sense in a low-cost, low-profile, and high-efficient antenna. The design and experimental results confirm that the solution is suitable for both one- and two-dimensional arrays in the millimeter-wave band.

Five-port MIMO antenna for n79-5G band with improved isolation by diversity and decoupling techniques

A compact five-port multi-input multi-output (MIMO) antenna for n79 (4.4–5 GHz) 5G band exhibiting pattern and polarization diversity with good isolation is proposed in this paper. This MIMO antenna system comprises of four linearly polarized (LP) endfire monopole antenna elements and one broadside L-shaped slot circularly polarized (CP) antenna element, which provides both pattern and polarization diversity. A T-shaped slot as a decoupling structure is further used to improve the interport isolation by 4 dB. The return loss bandwidth for all antenna elements is in the desired frequency range, and antenna elements provide isolation better than 23 dB. The pattern and polarization diversity provide a low envelope correlation coefficient and good isolation between any two-port of the MIMO antenna. For experimental verification, the proposed 5-port MIMO antenna system is fabricated and measured, which provides decent agreement with the simulated performance.

Patch antenna sensor for wireless ice and frost detection

A patch antenna sensor with T-shaped slots operating at 2.378 GHz was developed and investigated for wireless ice and frost detection applications. Detection was performed by monitoring the resonant amplitude and resonant frequency of the transmission coefficient between the antenna sensor and a wide band receiver. This sensor was capable of distinguishing between frost, ice, and water with total shifts in resonant frequency of 32 MHz and 36 MHz in the presence of frost and ice, respectively, when compared to the bare sensor. Additionally, the antenna was sensitive to both ice thickness and the surface area covered in ice displaying resonant frequency shifts of 2 MHz and 8 MHz respectively between 80 and 160 μL of ice. By fitting an exponential function to the recorded data, the freezing rate was also extracted. The analysis within this work distinguishes the antenna sensor as a highly accurate and robust method for wireless ice accretion detection and monitoring. This technology has applications in a variety of industries including the energy sector for detection of ice on wind turbines and power lines.

Design of Wearable Microstrip Patch Antenna Using T-Shaped Slot Antenna Compared with U-Shaped Slot Antenna for Health Monitoring Systems

Aim: To Enhance radiation characteristics such as bandwidth, gain and Voltage Standing Wave Ratio (VSWR) by designing innovative wearable T-shaped and U-shaped slot microstrip patch antennas using the FEKO tool for health monitoring systems by using FR4 substrate for an operating frequency ranging from 2.2 to 2.6 GHz. Materials and methods: The microstrip patch antenna ground plane is made with FR4 material by using FEKO software varying frequency between 2.2-2.6 GHz. The T-Shaped and U- shaped slot microstrip patch antennas was chosen as a group having 20 samples each. The bandwidth, gain and VSWR was obtained for T-shape and U-shape slot antennas. Results: T-shaped slot antennas (P=0.001) have significantly higher bandwidth, gain and lower VSWR than the U-shaped slot antenna (P=0.031).The obtained significance value is &lt;0.005 and mean values also increased. Conclusion: T-shaped microstrip patch antenna is designed and simulated using FEKO tool. The T-shape slot antenna has higher bandwidth, gain (Mean of T-shape 2.7238 and U-shape 1.4626) and VSWR (Mean of T-shape 8.3951 and U-shape 6.7675) when compared to U-shaped slot antenna. So, this antenna is very suitable for health monitoring systems.

Compact wideband substrate integrated waveguide bandpass filter for X/ Ku‐band application

This article presents a novel design of a compact substrate integrated waveguide (SIW) wideband bandpass filter. The proposed bandpass filter offers wide passband, wide lower, and upper band rejection characteristics. First, the filtering response is obtained by loading a single T-shaped slot on the top of the SIW structure. Later, to achieve wide passband and wide upper band rejection, a pair of T-shaped slots has been engraved on the top surface. To demonstrate the analysis, the proposed SIW filter has been simulated, fabricated, and tested. The measured S-parameters are in good agreement with the simulated results, showing wide passband from 8.05 to 15.45 GHz within a 3-dB fractional bandwidth of 62% at a center frequency of 12 GHz. The measured return loss is fairly good (>17 dB) within the passband and an insertion loss of 0.5 dB, including the loss from two SMA connectors. The fabricated prototype has a compact size of 0.248λg2.

Dual-Band Antenna Pair With Lumped Filters for 5G MIMO Terminals

This article proposes a novel design of the dual-band antenna pair. Starting from the single-band antenna pair composed of T-shaped monopole and T-shaped slot that are intersected with each other, orthogonal T-monopole and odd-symmetrical slot modes are excited. By adding symmetrical low-pass high-stop filters into the horizontal stub of the T-monopole and high-pass low-stop filters into the gap of the T-slot, an extra mode is introduced for each antenna, producing dual-band operation. Impedance bandwidths and radiation efficiencies of both bands can be adjusted flexibly using the filters. A detailed design guideline is given. The dual-band antenna pair operating at partial N78 (p-N78, 3.4~3.6 GHz) and partial N79 (p-N79, 4.8~4.9 GHz) is with a footprint of 15×6 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . The measured results show that the average efficiencies are both -3.4 dB at p-N78/p-N79 for the odd-symmetrical slot and -2.8 dB/-3.7 dB at p-N78/p-N79 for the T-monopole, isolations are better than -16.8 dB at p-N78 and -11.8 dB at p-N79, and ECCs are lower than 0.1 at p-N78 and 0.2 at p-N79. The proposed dual-band antenna pair exhibits great potential to be applied in the fifth-generation (5G) multiple-input multiple-output (MIMO) terminal.

Design and Analysis of a Circularly polarized flexible, compact and transparent antenna for Vehicular Communication Applications

A Compact, flexible, and circularly polarized transparent monopole antenna is proposed for vehicular communication applications by IEEE 802.1p standard. Canopy mesh is used as a conductive layer and the PDMS substrate is used as a substrate with dielectric constant e r = 2.66 and loss tangent tan 6= 0.023. The overall dimension of the proposed antenna is 20 × 20 × 1 mm3. The rectangular patch with a T-shape slot with a truncated corner and partial ground provide resonant frequency at 5.85 GHz with a reflection coefficient (S11) bandwidth of 5.2-6.86 GHz (1.66 GHz) and axial ratio(dB) bandwidth of 5.7 GHz-6.14 GHz (404 MHz).

10 Element Sub-6-GHz Multi-Band Double-T Based MIMO Antenna System for 5G Smartphones

A 10 element multiple input multi output (MIMO)/Diversity antenna system is considered to work in Sub-6 GHz frequency range. The proposed design can work in long term evolution (LTE) band 42(3.4-3.6 GHz), LTE band 43(3.6-3.8 GHz) and LTE band 46(5.15-5.925 GHz). The proposed design consists of 10 identical and highly isolated T-shaped slot antennas fed with T-shaped lines. All three bands have the return loss values (<-6 dB) and total antenna efficiency (>83%) in free space. The peak value of envelope correlation coefficient is 0.06 and the calculated value of ergodic channel capacity is found to be greater than 41bps/Hz in all the bands.The effect of hand grip as well as the presence of battery and LCD screen is investigated. Simulated results are validated via fabrication and measurement of the proposed design.

Design of substrate integrated plasmonicwaveguide bandpass filter with T-shaped spoof surface plasmon polaritons

ABSTRACT A novel substrate integrated plasmonic waveguide (SIPW) filter with T-shaped slot line spoof surface plasmon polaritons (SSPPs) is proposed in this paper. By etching the SSPPs array between the two rows of the metal vias of the substrate integrated waveguide (SIW) structure, the SIPW bandpass filter can independently adjust the low cutoff frequency by changing the SIW geometric parameters and the high cutoff frequency by changing the SSPP geometric parameters, respectively. Comparing with the traditional SIPW filter with signal layer or double layers linear slot line SSPPs, the proposed SIPW filter with T-shaped SSPPs has smaller circuit size thanks to the better electromagnetic field confinement ability of the T-shaped SSPPs. The dispersion properties of the SIW unit and the T-shaped SSPPs are discussed and the parameters effect on filter’s performance are numerically investigated. A bandpass SIPW filter with T-shaped SSPPs is designed and fabricated with the proposed design method. The measurement results show that its passband is at 5.6–7.3 GHz with the return loss higher than 10 dB and the maximal insertion loss 1.8 dB. Also, its out-of-band spurious rejection is higher than 40 dB at the bandwidth 8.1–14.8 GHz. The agreements between the simulated results and measured results demonstrate the effectiveness of the proposed SIPW filter with T-shaped SSPPs.

Multiband terahertz absorbers using T-shaped slot-patterned graphene and its complementary structure

A dual-band absorber using monolayer periodically T-shaped slot-patterned graphene at terahertz frequencies is presented. By changing the dimensions or Fermi levels of the T-shaped slot-patterned graphene, both of the two absorption bands will be adjusted. The absorber has the characteristics of polarization independence and incident angle insensitivity. Also, its complementary structure, i.e., using periodically T-shaped strip-patterned graphene, is investigated to design another dual-band absorber. Moreover, two triband absorbers are studied through periodically loading four more T-shaped slots and complementary strips in square graphene lattices, respectively. This paper provides a significant paradigm for designing different graphene-based absorbers with multiple absorption bands.

Self-Quadruplexing Circularly Polarized SIW Cavity-Backed Slot Antennas

In this communication, three self-quadruplexing circularly polarized (CP) antennas are presented in substrate integrated waveguide (SIW) technology for quad-band wireless services. The proposed antennas radiate from four unequal length T-shape slots etched on a square SIW cavity. The antennas are excited by four microstrip lines. The T-shape slot placed at each corner of the cavity creates orthogonal electric fields having 90° phase difference, which leads to CP radiation. The first antenna provides left hand circular polarization (LHCP), while the second antenna provides right hand circular polarization (RHCP) in all the bands. The third antenna offers LHCP in two bands and RHCP in other two bands. The sense of polarization can be changed by simply changing the slot orientation. Furthermore, the bands can be tuned almost independently over a wide range of frequency. For all the antennas, the measured isolations among the ports are more than 26 dB, front-to-back ratio (FTBR) is more than 15 dB, and the measured gain is at least 5.2 dBi.

A quad band planar slotted microstrip patch antenna for wireless applications

This research paper presents two different types of multiband patch antenna. The first design is a dual-band antenna and the second design is a quad-band antenna. Both the antennas have a compact size of , and is designed on FR4 substrate with loss tangent (=0.02, height (h)=1.6 mm, with dielectric constant of 4.4. The dual-band antenna operates at frequencies 3.9 and 5.71 GHz. These dual band operations are accomplished by utilizing L-shaped slot in the ground part and T-shaped slot in the radiating part of the patch antenna. The gain corresponding to the two frequency bands are 1.27 and 1.35 dB, respectively. The quad band antenna operates at frequencies 3.6, 4.9, 7.4 and 8 GHz. The gain corresponding to these frequencies are 0.18, 1.69, 2.25 and 3.99 dB. For achieving quad band operation from the dual band antenna the back plane L-shaped slot is modified by cutting a rectangular strip in the middle, hence dividing it into two different slots. The front plane is also modified by introducing two rectangular strips to the T-shaped patch. The proposed antenna shows multiband and has the advantage of simple structure compact size and good impedance matching. All the simulations of the proposed design are carried out in HFSS v.13.0.

A Double Combined Symmetric T-shaped Slots and Rotated L-shaped Strips Inspired UWB Antenna for C and X-band Elimination Filters

In this paper, we present a modified UWB antenna with hexagonal slotted ground plane inspired with a double combined symmetric T-shaped slots and dual rotated L-shaped strip for dual band notched characteristics. Initially, the operating frequency range is from 3GHz to 12 GHz. To eliminate the unwanted C-band (3.625-4.2GHz) and the entire uplink and downlink of X-band satellite communication systems (7.25 -8.39 GHz) frequency bands, we are investigating the conventional UWB patch antenna and loaded it with a mentioned strips and slots respectively. The performances of the antenna are optimized both by CST Microwave Studio and Ansoft HFSS. To further analyze the parametric effects of the slots and strips, the surface current distribution is presented and discussed. The antenna gain versus frequency gives an acceptable value except the notched band regions, these values are reduced from its normal to be a negative in the notched bands (3.625-4.2GHz) and (7.25 to 8.39 GHz).

Simulation on wideband antenna based on Polydimethylsiloxane (PDMS) for medical imaging application

This paper presents an antenna for the medical imaging application which can detect unusual tissues on any part of the body. A design of wideband antenna with wearable properties is proposed for the medical imaging application. The wideband antenna is designed with introducing notches to the patch and a t-shaped slot at the partial ground. Polydimethylsiloxane (PDMS) is introduced to the antenna for the implementation of the wearable antenna. The proposed antenna operated in a frequency range of 3GHz to 6GHz. The antenna that embedded with PDMS shows a good agreement to the antenna without PDMS. The overall dimension of the antenna is 24mm (W) x 38mm (L) which consider is a miniature antenna. This proposed design gives an alternative solution for the antenna which cannot be wear on the body and protect the antenna. The introduction of PDMS will reduce the signal reflection cause by the high coupling of the human body.

Reconfigurable Dual-/Triple-Band Circularly Polarized Dielectric Resonator Antenna

In this letter, a probe-fed reconfigurable dual-/triple-band circularly polarized (CP) Spidron fractal dielectric resonator antenna (SFDRA) is proposed. Initially, a dual-band CP SFDRA is designed. An eigen-mode simulation of an isolated SFDR concludes that the quasi-TM $_{11\delta }$ and quasi-TM $_{21\delta }$ are excited in the lower band, whereas the quasi-TE $_{12\delta }$ mode is excited in the upper CP band. The modes of the lower CP band are separated by etching a T-shaped slot from the ground plane, thereby achieving overall triple-band circular polarization. In addition, the TSS being $\lambda _g/2$ in length at 2.64 GHz produces a band-notch function. CP band reconfigurability is attained by placing a diode D1 across the width of the TSS such that the on -/ off -state of the D1 radiates dual-/triple-band CP waves. The measurement results in the on -[ off ]-state show the impedance bandwidths for $\mathopen |$ $S_{11}\mathclose | $-$ 10 dB of 57.60% (2.2–3.98 GHz) [14.44% (2.12–2.45) and 40.48% (2.64–3.98 GHz)] and the 3 dB axial-ratio bandwidths of 24% (2.31–2.94 GHz) and 6.82% (3.68–3.94 GHz) [6.34% (2.29–2.44 GHz), 6.65% (2.76–2.95) and 7.09% (3.67–3.94 GHz)] in an ascending order of the frequency. A reasonable match is observed between the simulated and experimental data.

Polarization-independent hybrid plasmonic coupler based on T-shaped slot waveguide

In this paper, a novel polarization-independent hybrid plasmonic coupler based on a T-shaped slot waveguide is proposed and investigated by numerical simulations using the finite element method. The structure supports both the TE-polarized slot waveguide mode and the TM-polarized plasmonic mode, offering a greater possibility to achieve the polarization-independent operation. The simulation results show that with proper structural parameters, the waveguide coupler with high extinction ratios of 31.2 dB (TE) and 30 dB (TM) and low insertion losses of 0.38 dB (TE) and 2.04 dB (TM) can be achieved at a telecommunication wavelength of 1550 nm. An investigation of the influence of structural perturbations indicates that the proposed coupler also has a good tolerance to fabrication errors. The proposed structure has potential applications in the field of subwavelength integrated photonic circuits.

Orthogonally Polarized Dual Antenna Pair With High Isolation and Balanced High Performance for 5G MIMO Smartphone

For the first time, zero-ground-clearance dual antenna pair with high isolation and balanced high performance is proposed. A T-shaped monopole intersects with a T-shaped slot that is etched on a large ground edge, constituting the CPW-fed dual antenna pair. By exploiting the odd and even modes of the CPW structure, two orthogonal characteristic modes including the in-phase current and monopole modes can be excited, generating high port isolation. Both modes are unbalanced mode, which means that the ground currents can be fully excited, so the two antennas are with balanced high performance. A sub-6 GHz antenna pair that occupies a footprint of $15\times 7$ mm2 ( $0.18\,\,\lambda \,\times 0.08\,\,\lambda$ ) is analyzed and the simulated results show an isolation of better than −24 dB and an envelope correlation coefficient (ECC) of lower than 0.0016, −6 dB bandwidths of 230 and 240 MHz, and average efficiencies of 57.9% and 57.4%. A four-antenna multiple-input multiple-output (MIMO) array is fabricated and measured to verify the feasibility. The measured isolations and ECCs of the two modes are, respectively, better than −20.0 dB and 0.04, −6 dB bandwidths are 230 MHz/240 MHz and 220 MHz/230 MHz, and average efficiencies are 54.5%/50.2% and 49.9%/48.6%. The proposed dual antenna pair exhibits a great potential for 5G MIMO smartphone application.

Circularly Polarized T-Shaped Slot Waveguide Array Antenna for Satellite Communications

A novel circularly polarized waveguide slot array for satellite communications is proposed. The antenna features a unique feeding network and a unit cell that consists of a pair of simple T-shaped waveguide slots. The proposed configuration not only eliminates grating lobes, which are often seen in conventional waveguide slot arrays, but also simplifies the fabrication process without any sacrifice in the performance, while also allowing scalability. A prototype 6 × 8 array antenna is designed at 29.5 GHz, and fabricated by dip brazing. A high gain of 21.9 dBi and a -10 dB impedance bandwidth of 1 GHz are achieved with an axial ratio (AR) of 1.3 dB without any grating lobes. The measured results are in very good agreement with the simulated results.

Very-Low-Profile Grounded Coplanar Waveguide-Fed Dual-Band WLAN Slot Antenna for On-Body Antenna Application

A very-low-profile grounded coplanar waveguide (GCPW)-fed slot antenna with an antenna thickness of 0.8 mm (about 0.0064λ at 2.4 GHz) and a compact size of 15 mm × 40 mm (about 0.12λ × 0.32λ at 2400 MHz) for 2.4/5.8 GHz dual-band wireless local area network on-body antenna application is presented. The GCPW slot antenna consists of a top ground with the GCPW feedline and radiating slot embedded thereon and a bottom ground spaced 0.8 mm to the top ground. The radiating slot is an asymmetric T-shaped slot having a longer slot path for 2400~2500 MHz band and a shorter slot path for 5725~5875 MHz band. It is convenient to tune the dual-band operation by adjusting the lengths of the longer and shorter slot paths, respectively. Additionally, owing to the presence of the bottom ground, the GCPW slot antenna has decreased backward radiation. This causes the antenna's impedance matching to be very slightly varied when it is in the proximity of a human body.