Orthogonal Feed Lines Research Articles

A Compact Tri-Band Penta-Polarization Reconfigurable Planar Antenna for Interference Management in 5G Ultra-Dense Network Environment

Interference and multipath are the most common issues in the wireless domain due to the coexistence of a large number of wireless nodes operating within the constraint spectrum. A compact planar antenna with five reconfigurable polarization states in three distinct operating bands is presented in this article. A square patch is enclosed by a square outer ring in the design, and these antennas are coupled-decoupled successively using switching diodes to excite three distinct operating bands. Coplanar microstrip lines are used to feed the orthogonal edges of the antenna. The diagonal corners of the inner and outer ring patches are truncated to realize dual circular polarization (CP) states with proper biasing. Switching diodes are placed at the etched corners to realize vertical (VP) and horizontal (HP) polarization. Both the orthogonal feed lines are activated simultaneously with identical phase and amplitude to realize 45° linear polarization. A low-profile, single-feed, compact prototype reconfigurable microstrip antenna (MSA) is finally designed, fabricated, and measured at 1.8 GHz, 2.4 GHz, and 5.8 GHz bands, respectively. Each operating band shows five distinct operating states. The simulation results for all fifteen states are found to be consistent with the measurement.

A Compact Dual-Band Self-Diplexing MIMO Patch Antenna for ISM and X-Band Communications

A compact, dual-band, and self-diplexing MIMO patch antenna with a shared aperture is presented for Industrial scientific medical (ISM) band and X-band communications. The structure consists of two orthogonal feed lines and a rectangular slot in a square patch. The size of the FR4 substrate is 50 × 50 × 1.6 mm3. The designed structure operates at 5.8 (ISM) and 8 GHz (X-band) frequencies independently with a simulated peak gain of 5.46 and 3.59 dBi respectively. A 13 dB of isolation is obtained for the two orthogonal ports. The obtained frequency ratio range is 1.20-1.33 over the reflection bandwidth. The design structure is fabricated and validated experimentally. The compactness and promising performance in terms of low ECC (Envelope Correlation Coefficient) (<0.1), high peak gain can make the proposed antenna a choice for current wireless devices.

A low profile single feed compact dual-band penta-polarization agile microstrip antenna for interference mitigation in point to point link in Ultra-Dense environment

This study takes an antenna perspective approach to mitigate signal interference issues in ultra-dense environment along with communication and signal processing domain. A compact single layered dual-band penta-polarization agile microstrip patch antenna (MSA) using single feed is studied and proposed. Each band switches between five distinct polarization states. Additionally, the proposed antenna possesses a very low profile of less than 0.01λ (λ free-space wavelength). A square patch is enclosed by a square ring to attain two distinct reconfigurable frequency bands by using switching diodes and biasing networks. Orthogonal microstrip lines connected with a single coax feed are selectively chosen by biasing network to excite the adjacent patch edges to achieve dual linear polarization (LP). Circular polarization (CP) with dual sense of rotation at each band is attained by switchable diagonal-truncated corners of outer ring. Subsequently, 45° slant polarization is achieved by simultaneous activation of the orthogonal feed lines with equal phases and amplitude. A penta-polarized antenna prototype is designed and fabricated to operate at 5.2 GHz and 5.8 GHz bands respectively. Simulation results of all ten reconfigurable states are found to be consistent with the measurement.

Highly-Miniaturized Dual-Mode Bandpass Filter Based on Quarter-Mode Substrate Integrated Waveguide With Wide Stopband

This paper presents a novel design of a highly-miniaturized dual-mode bandpass filter (BPF) employing a quarter-mode substrate integrated waveguide (QMSIW). The QMSIW resonator is based on a square cavity with metallic vias along two sides, and open-ended edges at the remaining sides that contain orthogonal feed lines. An open slot is introduced along the two sides of the square cavity with metallic vias to form a magnetic wall. A single metallic via is assigned at the corner of the two open-edged sides to form an electrical wall, which produces different resonances. By loading a slot diagonally, the mode frequencies can be controlled independently, which allows us to realize a second-order BPF. The detailed design steps and a flowchart explaining the filter’s topology evolution are presented. The eigen-mode analysis, field distributions, coupling matrix, and full-wave simulation of the proposed QMSIW filter topology are used to determine the filter’s operating principle. To verify the proposed theory, a second-order BPF is realized, fabricated, and demonstrated experimentally. The BPF prototype exhibits excellent performance such as a small footprint of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.019\lambda ^{2}$ </tex-math></inline-formula> , a wide passband of 34.8-percent, low insertion loss of 0.43 dB, and a wide stopband of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$3.36f_{0}$ </tex-math></inline-formula> with a rejection level greater than 20 dB. Excellent consistency is found between the EM-simulated and measured responses of the device.

Compact dual-mode microstrip bandpass filter based on slotted square patch resonator

PurposeThe purpose of this paper is to present the design of a compact microstrip bandpass filter (BPF) in dual-mode configuration loaded with cross-loop and square ring slots on a square patch resonator for C-band applications.Design/methodology/approachIn the proposed design, the dual-mode response for the filter is realized with two transmission zeros (TZs) by the insertion of a perturbation element at the diagonal corner of the square patch resonator with orthogonal feed lines. Such TZs at the edges of the passband result in better selectivity for the proposed BPF. Moreover, the cross-loop and square ring slots are etched on a square patch resonator to obtain a miniaturized BPF.FindingsThe proposed dual-mode microstrip filter fabricated in RT/duroid 6010 substrate using PCB technology has a measured minimum insertion loss of 1.8 dB and return loss better than 24.5 dB with a fractional bandwidth (FBW) of 6.9%. A compact size of 7.35 × 7.35 mm2 is achieved for the slotted patch resonator-based dual-mode BPF at the center frequency of 4.76 GHz. As compared with the conventional square patch resonator, a size reduction of 61% is achieved with the proposed slotted design. The feasibility of the filter design is confirmed by the good agreement between the measured and simulated responses. The performance of the proposed filter structure is compared with other dual-mode filter works.Originality/valueIn the proposed work, a compact dual-mode BPF is reported with slotted structures. The conventional square patch resonator is deployed with cross-loop and square ring slots to design a dual-mode filter with a square perturbation element at its diagonal corner. The proposed filter exhibits compact size and favorable performance compared to other dual-mode filter works reported in literature. The aforementioned design of the dual-mode BPF at 4.76 GHz is suitable for applications in the lower part of the C-band.

Magnetless nonreciprocal filtering diplexing antenna

AbstractThis paper presents a magnetless nonreciprocal diplexing antenna that uses time modulation. The device combines the functions of diplexers, filters, isolators, and antennas in a highly integrated manner. The magnetless nonreciprocity response is achieved by applying time modulation to the resonators of the filtering structures. These resonators are implemented in quarter‐wavelength microstrip lines terminated with varactors that are time modulated by low‐frequency signals fed from Coplanar Waveguides built on the ground plane of the microstrip structure. A prototype multilayer patch antenna is fabricated, which is fed through two orthogonal feedlines and the radiating square patch is coupled by a square ring slot etched in the ground plane. The experimental results show that a gain of 4 dB, out‐of band rejection of 22 dB, in‐band isolation of 20 dB, and inter‐port isolation of 35 dB is obtained at both 1.5 GHz (lower band) and 1.8 GHz (higher band).

Design of Microstrip Dual-Mode Wideband Bandpass Filter with Controlled Center Frequency and Bandwidth Using Bandstop Filter Topology

ABSTRACT This paper discusses a new method for designing a microstrip dual-mode, sharp skirt, wideband bandpass filter with controlled center frequency and bandwidth from bandstop filter topology. A meander closed loop resonator with directly connected orthogonal feed lines provides a Bandstop filter (BSF) with reduced size. A pair of L-shaped open stubs introduced along the diagonal axis D-D1 realizes a wide passband within the rejection band (0.93–4.13 GHz) of the bandstop filter with sharp stopbands on either side of the passband. Furthermore, the effect of L-shaped open stubs susceptance on passband edges is demonstrated. A quarter wavelength stepped impedance shunt stub (SISS) connected at is proposed to achieve additional transmission zeros in the upper and lower rejection bands to improve the sharpness of filter response. Both center frequency and bandwidth of the proposed filter are controlled by the impedance ratio (R) of the SISS element. The proposed filter is simulated using ADS, fabricated and measured using Vector Network Analyzer (VNA). A good agreement is achieved between simulated and measured results.

Highly Miniaturized Self-Diplexed U-Shaped Slot Antenna Based on Shielded QMSIW

This article presents an efficient yet simple design approach to highly miniaturized cavity-backed self-diplexing antenna (SDA) with high-isolation. The structure employs a shielded quarter-mode substrate integrated waveguide (QMSIW). Two U-shaped slots are engraved on the top conducting plane, which realize two frequency bands and significant size reduction. The slots are excited by two independent 50Ω orthogonal feed-lines to achieve high isolation while enabling radiation at 3.5 GHz and 5.4 GHz. The proposed design approach allows us to design the two frequency bands independently from each other. The SDA structure is verified using an equivalent circuit model, full-wave electromagnetic (EM) analysis, and experimental validation of the antenna prototype. Excellent consistency between simulated and measured responses has been demonstrated. According to the measurement, the SDA has peak gains of 5.26/5.60 dBi at 3.5/5.4 GHz, and the return loss better than 21.6 dB. The isolation between ports is greater than 40 dB, whereas excellent front-to-back-ratio and co-to-cross polarization are obtained for the proposed SDA. Furthermore, the total size of the SDA is only 0.129 λ2, with λ being the guided wavelength at 3.5 GHz.

Design of a compact orthogonal fed self‐diplexing bowtie‐ring slot antenna based on substrate integrated waveguide

In this article, a novel design of compact cavity-backed slot antenna based on substrate integrated waveguide (SIW) technology is presented for dual-frequency communication services. A single layer printed circuit board is applied to implement the proposed antenna. The bowtie-ring slot engraved on the SIW square cavity is excited using two orthogonal microstrip feed lines to operate at two distinct frequencies (6.62 GHz and 11.18 GHz). The proposed antenna allows each of these frequencies to be designed independently. A prototype of the proposed cavity-backed antenna that radiates at both 6.62 GHz and 11.18 GHz is fabricated and measured. The port isolation better than 29.3 dB is achieved by utilizing the transmission zeros (TZs), which are produced due to the orthogonal feed lines, TE110 mode and coupling between the TE120 and TE210 modes. The measured peak gains of the proposed diplexing antenna are 5.77 dBi and 5.81 dBi at lower and upper resonating frequencies, respectively. The proposed dual-frequency antenna exhibits the front-to-back-ratio (FTBR) and cross-polarization level greater than 26 dB and 21 dB, respectively, at both resonating frequencies.

A Triband SIW Cavity-Backed Differentially Fed Dual-Polarized Slot Antenna for WiFi/5G Applications

A tri-band differentially fed dual-polarized slot (DFDPS) antenna is developed for indoor WiFi/5G wireless communications. The triband antenna is made up of two crossed slots with four pairs of L-shaped slots. The lower and higher bands are generated by the crossed slots, and the middle band is attributed to the L-shaped slots. Eight shorting pins are introduced for improving the impedance matching for all the three bands. A substrate-integrated waveguide (SIW) cavity is employed to back the antenna for unidirectional radiation. Two orthogonal feedlines are applied to differentially feed the antenna for dual polarization. The antenna has a low-profile of about $0.054~\lambda _{\mathbf {2.4}}$ , where $\lambda _{\mathbf {2.4}}$ is the wavelength at the lowest frequency of 2.4 GHz in free space. It is shown that the triband antenna can operate in three bands of 2.4–2.51, 3.29–3.6, and 4.8–5.05 GHz with good unidirectional patterns.

Compact high-isolation self-diplexing antenna based on SIW for C-band applications

ABSTRACTThis paper presents a novel compact high-isolation cavity-backed inverted U-shaped slot antenna using substrate-integrated waveguide (SIW) for C-band applications. The SIW cavity is loaded by an inverted U-shaped slot that produces two fictitious aperture for radiation at two distinct frequency bands and to exhibit self-diplexing antenna (SDA) characteristics. Two orthogonal microstrip feed lines are applied for excitation of fundamental mode () and two degenerated modes ( and ). The perturbation of these modes due to slot loading allows to achieve size miniaturization. Compared with conventional SIW cavity without slot, the proposed SDA allows a size reduction of 56%. High isolation is achieved due to the transmission zeros produced by these modes and orthogonal feed lines. This isolation is further improved (>40.5 and >32.8 dB) due to off-centered input ports that creates very weak cross-coupling path between them. The resonating frequencies of the proposed SDA can be designed individually. Finally, an SDA working at 4.29 and 7.52 GHz is fabricated for validation of simulated performances. The measured gains of the fabricated SDA are 5.38 and 5.82 dBi at the resonating frequencies of 4.29 and 7.52 GHz, respectively. A good consistency is found between measured and simulated results.

Substrate integrated waveguide based cavity‐backed self‐triplexing slot antenna for X‐Ku band applications

A planar substrate integrated waveguide (SIW) based cavity-backed self-triplexing slot antenna is proposed for X-Ku band applications. The antenna comprises of the SIW cavity, radiating slots, and feeding networks. The radiating slots; that are etched on the upper metallic plane of the SIW, are backed up by the three radiated quarter cavities (QCs). The radiating slots in the respective QCs are of different lengths, excited by three separated orthogonal feed lines to resonate at three different frequencies as 11.01, 12.15, and 13.1 GHz. By fine-tuning the antenna parameters, an intrinsic input port isolation of better than 26 dB is realized which helps in achieving the self-triplexing property. The behaviors of individual cavity modes at three resonant frequencies are explained with the help of Z-parameter. The proposed antenna layout is easy to integrate with the planar circuit. The proposed antenna is fabricated and measured results display a close concern with the simulated results. Moreover, a unidirectional radiation pattern and gain of 5.1, 5.54, and 6.12 dBi at resonant frequencies are realized.

Low-Profile Aperture-Coupled Patch Antenna Array for CubeSat Applications

This paper presents the design, simulation, and measurement results of a dual aperture-coupled microstripline-fed antenna array with circular polarization at the C-band for small satellites applications. The antenna array was designed at a center frequency of 5.5 GHz, and it has a two-port isolation bandwidth of 25 MHz above 20 dB while the axial ratio is below 1 dB. The main objective is to produce a four-patch antenna array to be mounted on CubeSat deployable wings along with a layer of solar panels, maximizing the usable space and obtaining a better link budget for a standardized Cubesat of 10 cm $\times10$ cm $\times10$ cm. The orthogonal feedlines’ isolation between Tx/Rx signals and a minimization of the multi-layer design provide a lower profile approach considering the state-of-the-art. The significant thickness reduction combined with a new perspective of having both deployable wings transmitting and receiving signals lead to a notable improvement of the overall system. This work is relevant due to the demand for high-performance antenna systems that may expand the capabilities of CubeSats, considering the importance of using an antenna array instead of a single element approach.

A wideband dual‐circularly polarized 2 × 1 array antenna using multi‐layer substrate for compact structure

AbstractA novel compact dual‐circularly polarized (CP) 2 × 1 microstrip array antenna with wideband characteristic is proposed. The antenna is realized using multi‐layer technique. The antenna consists of two orthogonally fed patch elements integrated with a 90° branch‐line coupler for achieving dual‐CP operation. The complete feed network, inspired by double‐sided MIC technology, is designed using microstrip lines and slot lines distributed in different three metal layers. ±90° out‐of‐phase signals caused by the branch‐line coupler are combined with two orthogonal feed lines of the patches to excite right‐hand circular polarization (RHCP) or left‐hand circular polarization (LHCP). More than 40% size reduction is achieved by employing multilayer structure instead of single‐layer structure. The measured 3‐dB axial ratio bandwidths of RHCP/LHCP are 8.31/10.19%. Peak gain is more than 9 dBic with good CP radiation performance. The antenna performance is validated by measured data.

Novel Dual band SIW Filter Using Quad mode Cavity

A dual-band bandpass substrate integrated waveguide (SIW) filter is proposed using a quad-mode cavity in this paper. First two degenerative modes (TE102 and TE201) with via perturbation give the first passband. The second passband is realised by using higher modes (side and diagonal modes of TE202) which are obtained by putting square slot at the center of the cavity. The square slot increases the frequency ratio of the center frequencies of first and second passbands. Moreover, orthogonal feed-lines are used in the proposed design to increase transmission zeros (TZs) which helps to improve the selectivity and out-of-band rejection of the filter. Designed and fabricated a dualband filter prototype using a single layer printed circuit board (PCB) technology, size is only 19 mm × 19 mm. The insertion losses are 2.1 dB and 2.4 dB, and fractional bandwidths of 3.40 per cent and 2.00 per cent at 11.00 and 15.58 GHz, respectively. The measurement results show close agreement with the simulation results.

Dual‐band dual‐polarised microstrip antenna with improved inter‐port isolation

This Letter presents the development of a dual linearly polarised microstrip antenna for S- and C-band with improved isolation and bandwidth. The antenna is dual linearly polarised at each of the bands. The S-band patch is proximity coupled to two orthogonal feed lines, whereas the C-band patches are aperture coupled to other two mutually orthogonal feed lines. The antenna results in an impedance bandwidth ≥ 3.65% with an isolation ≥ 26 dB at the S-band ports. At the C-band ports, it also displays an isolation ≥ 45 dB over the entire operating bandwidth of ≥ 21%. All these results are improved compared to the earlier reported investigations.

Dual-Band and Polarization-Flexible CRLH Substrate-Integrated Waveguide Resonant Antenna

A dual-band and polarization-flexible substrate-integrated waveguide (SIW) resonant antenna based on composite right-/left-handed (CRLH) structure is presented in this letter. The proposed antenna consists of a CRLH SIW resonator and dual feeding lines. A slot and surface-mount technology capacitors on the top metallic layer of SIW resonator provide necessary reactance to realize multiresonance CRLH structure. Due to the intrinsic multiband characteristic of a CRLH structure, the proposed antenna can provide dual-band broadside radiations. Polarization flexibility is realized by two orthogonal feedlines. Utilizing the CRLH resonator instead of the conventional square resonator, such as patch antenna, allows antenna miniaturization. The electrical lengths of the sidewalls for the proposed square SIW resonant antenna are 75% (for first resonant mode) and 44% (for second resonant mode) shorter than that of the previously proposed dual-band polarization-flexible SIW antenna. To highlight the unique advantages, the dual-band circularly polarized antenna array based on the proposed antenna element is presented. Dual-band circularly polarized radiation is supported by the dual-band CRLH transmission-line-based feeding network.

Compact wideband dual circularly polarized L‐shaped slot antenna

AbstractA wideband dual circularly polarized (CP) L‐shaped slot antenna with compact size is proposed. The antenna consists of an L‐shaped slot, two asymmetric microstrip feedlines and perturbed stub at the lower left corner of the slot. The initial L‐slot is used to obtain the first CP mode in lower band while the upper CP mode is realized by the orthogonal feedlines. Then, additional stub is also introduced to widen the axial ratio (AR) bandwidth. The proposed antenna with an area of 24 × 24 mm2 was fabricated and measured to demonstrate the final design. The L‐shaped slot antenna has a −10‐dB bandwidth of 97.9% (3.6‐10.5 GHz) and a 3‐dB AR bandwidth of 94.9%. In addition, the isolation is better than 12 dB within the CP band.

Dual-Band and Polarization-Flexible Cavity Antenna Based on Substrate Integrated Waveguide

In this letter, a novel dual-band and polarization-flexible substrate integrated waveguide (SIW) cavity antenna is proposed. The SIW cavity used for the antenna is excited by a conventional TE120 mode for its first resonance. With the intervention of the slot, a second resonance excited by a modified- TE120 mode is also generated, thereby providing a broadside radiation pattern at two resonant frequencies. In addition, the proposed antenna has two orthogonal feeding lines. Therefore, it is possible to provide any six major polarization states. In this letter, three major polarization cases are simulated and compared to measured results. Since modern communication systems require multifunctional antennas, the proposed antenna concept is a promising candidate.

A Broadband Dual Circularly Polarized Square Slot Antenna

A novel coplanar waveguide-fed broadband dual circularly polarized square slot antenna is presented. The antenna consists of a square slot, two asymmetric T-shaped feed lines in orthogonal direction protrude from signal lines, and an inverted-L grounded strip with three straight strips at the corner of the slot adjacent to both the feed lines. The circular polarization is obtained due to orthogonal feed lines. Axial ratio (AR) bandwidth is significantly enhanced because of inverted-L grounded strip with attached three straight strips. The 3-dB AR bandwidth of the antenna is about 60% in which return loss, and isolation are better than 10 and 15 dB, respectively.