Open-ended Slot Research Articles

Eight Element Multiple-Input Multiple-Output (MIMO) Antenna for 5G Mobile Applications

This work presents a systematic design of high performance eight element antenna array for a 5G mobile terminal operating at 2.6/3.5 GHz bands. The proposed eight element slot antenna array based on unit monopole slot antenna embedded in the metal casing or ground resonates at fundamental mode at 2.6 GHz. The antenna array is developed from four antennas (open-end slot antenna) etched near to the corner edges of the printed circuited board with supported pairs of vertically mounted slot antennas in middle section of the long edge ground plane. This combination of the antenna elements provided pattern diversity and enabled the smartphone in the reception of the signal in a different direction. The impedance bandwidth based on -10 dB return loss criteria cover from 2.4 GHz to 3.6 GHz includes the two allocated bands of (2400 MHz to 2600 MHz) and (3400 MHz to 3600 MHz) for 5G cellular communication systems. The vital MIMO performance measures as envelope correlation coefficient or ECC is less than 0.2 for any two antenna array meeting the required standard of less than 0.5 alongside the mean effective gain or MEG ratio of any two antenna meeting the required standard of less than 3 dB for power balance and optimal diversity performance. As modern smartphone demand desires slim handsets, the after mentioned compact multiple antenna structure can be easily implemented for the future smartphones as it utilizes the conductive sheet or chassis and the middle vertically mounted antenna do not use the additional space of the chassis or ground. The customer hand or human hand effect on the multiple antenna array to mimic the use of mobile phone customer is also studied. The maximum MIMO Channel capacity based on measured result is 34.25bps/Hz and is about 3 times of 2 × 2 MIMO operations.

Circularly Polarized Annular Ring Antenna With Wide Axial-Ratio Bandwidth for Biomedical Applications

This paper proposes a novel circularly polarized antenna operating at 2.4-2.48-GHz industrial, scientific, and medical (ISM) band for biomedical applications. This proposed structure is developed from a simple pin-loaded patch antenna, whose circular polarization (CP) is mainly attributed to the loading of shorting pins and L-shaped open-end slot. Based on this, pin-loaded annular ring (PLAR) with dual-mode operation is adapted to introduce another resonance. In addition, two closely coupled rectangular patches are added to bring these two resonant frequencies close to each other in muscle. Furthermore, by introducing arc-shaped slots, CP property and improved impedance matching are achieved with size miniaturization. This proposed structure shows a simulated impedance bandwidth of 8% and a wide axial-ratio (AR) bandwidth of 19.1%. Finally, measurement is performed for the proposed antenna, and the results coincide well with the simulation ones, indicating that it is a good candidate for biomedical applications.

Low profile single feed monopole antenna for quad-band circularly polarised applications

ABSTRACTA single fed monopole antenna for circularly polarised quad-band applications is presented. The antenna radiator is comprised of half ring-shaped arcs integrated with the 50Ω microstrip feed line. In the proposed design, the circular polarisation is achieved by means of integrating ring, stubs and implanting an open-ended C-shaped slot in the ground surface. The designed antenna has a −10 dB impedance bandwidth in the range of 2.41 GHz to 4.14 GHz and 4.34 GHz to 6.33 GHz. The 3-dB axial ratio bandwidth varies from 3.01 to 3.21 GHz, 3.46 to 3.79 GHz, 4.53 to 4.68 GHz and 5.08 to 5.10 GHz, therefore, exciting four circularly polarised bands. The proposed antenna covers almost all the IEEE 802.11 and IEEE 802.16 standards and may be a suitable candidate for WLAN and WiMAX applications. The optimisation of the designed antenna is conducted using tool Ansys HFSS and found simulated results in a good match with measured results.

Mutual Coupling Reduction Using a Protruded Ground Branch Structure in a Compact UWB Owl-Shaped MIMO Antenna

A compact ultra-wideband (UWB) multiple input-multiple output (MIMO) antenna with high isolation is designed for UWB applications. The proposed MIMO antenna consists of two identical monopole antenna elements. To enhance the impedance matching, three slots are formed on the ground plane. The arc structure as well as the semicircle with an open-end slot is employed on the radiating elements the fact which helps to extend the impedance bandwidth of the monopole antenna from 3.1 up to 10.6 GHz, which corresponds to the UWB band. A ground branch decoupling structure is introduced between the two elements to reduce the mutual coupling. Simulation and measurement results show a bandwidth range from 3.1 to 11.12 GHz with |S11_|<−15 dB, |S21_|<−20 dB, and ECC < 0.002.

Design of a self-diplexing antenna using SIW technique with high isolation

In this paper, a novel and small substrate integrated waveguide (SIW) based self-diplexing antenna is presented. The proposed antenna exploits two quarter-mode SIW cavity resonators for radiation, which are realized by splitting a half-mode SIW cavity with the help of one open-ended slot. Each quarter-mode cavity resonator is excited separately by microstrip feedlines. By properly adjusting the corresponding dimensions of the antenna, a very high isolation of better than −30 dB is obtained between the input ports that helps to realize a self-diplexing phenomenon. The antenna exhibits two resonant frequencies of 6.44 and 7.09 GHz, with the corresponding gain values of 3.2 and 4.8 dBi, respectively. Moreover, the antenna shows unidirectional and stable radiation patterns at both operating frequencies, while it maintains a planar and simple configuration, which can be rescaled for any other desired frequency.

Printed λ/4 folded monopole with printed circuit board slot for penta-band

ABSTRACTIn this paper, a printed λ/4 folded monopole with a printed circuit board slot is proposed for penta-band mobile terminals. The proposed antenna consists of a folded monopole fed by a coupling feed to reduce the length of the antenna and a printed circuit board slot to obtain an additional resonance in low band. The coupling feed can be represented by a series capacitance which reduces the large input impedance seen at the λ/4 mode for a conventional folded monopole and leads to a successful excitation of the λ/4 mode for the proposed antenna. In addition, the open-ended slot with a length of λ/4 on the printed circuit board is implemented to make an additional resonance. By designing the slot near the feeding point and flowing a surface current on the printed circuit board by itself, the proposed open-ended slot does not require a feed line across the slot. To verify the feasibility, we have simulated and measured the characteristics of the proposed antenna such as reflection coefficient, total efficiency, and far-field radiation pattern. The overall dimension of the antenna is 37.5 mm (length) × 8 mm (width) × 0.8 mm (height), and the total efficiencies are measured more than 60% in the penta-band.

A Wideband Differentially Fed Dual-Polarized Stacked Patch Antenna With Tuned Slot Excitations

In this communication, a novel wideband differentially fed dual-polarized stacked patch antenna with tuned slot excitations for base station application is proposed. The antenna is composed of a driven patch excited by tuned slot excitations, a parasitic patch to enhance the impedance bandwidth, and a ground plane to obtain unidirectional radiation. Two pairs of the slot excitations etched on the opposite edges of the driven patch are used to obtain dual polarizations. Each tuned slot excitation has an open-ended slot and a $\Gamma $ -shaped feeding line. To connect to the differential circuit easily, a rotated feeding mechanism is adopted. A prototype of the proposed antenna is fabricated and tested. Measured results show that the antenna has a wide differential impedance bandwidth of 49.4% (1.66 to 2.75 GHz) for $\vert \text{S}_{\mathrm{ dd11}}\vert ~f-15 $ dB. In addition, a high differential port isolation of more than 37 dB, a stable radiation pattern with a 3 dB beamwidth of 61°±5°, and a stable gain around 8.7 dBi are obtained within the operational band. The proposed antenna features wideband, high port isolation, and stable gains, and it is a promising candidate for base station systems using differential signals.

Tri-Polarized 12-Antenna MIMO Array for Future 5G Smartphone Applications

A tri-polarized 12-antenna array working in the 3.5-GHz band (3.4–3.6 GHz) for future 5G (the fifth generation mobile communication) multiple-input multiple-output (MIMO) operations in the smartphone is presented. In order to reduce the mutual couplings and simplify the design process, orthogonal polarization technique is utilized. By combining a quarter mode substrate integrated wave-guide antenna and two open-end slots, a compact 3-antenna tri-polarization block operating in the 3.5-GHz band is achieved within a small volume of $17\times 17\times6$ mm3. Thanks to the orthogonal polarization features, the three antennas within the block are able to have good impedance matchings and low mutual couplings between antennas. By integrating four such tri-polarization blocks, a 12-antenna MIMO array is then designed for smartphone applications. It is also due to the tri-polarization feature, the proposed array could attain acceptable isolations and low correlations between antennas with only two additional decoupling structures. The proposed array is fabricated and tested, good antenna performances, such as return loss better than 10 dB, isolation higher than 12.5 dB, and antenna efficiencies higher than 50%, are obtained. The channel capacity of the 12-antenna array is calculated to be about 57 bps/Hz in a $12\times12$ MIMO system with 20-dB signal-to-noise ratio, which indicates the proposed array using tri-polarization technique is a good choice for future 5G terminals.

A Wideband Circularly Polarized Conformal Endoscopic Antenna System for High-Speed Data Transfer

In this paper, a conformal wideband circularly polarized (CP) antenna is presented for endoscopic capsule application over the 915-MHz Industrial, Scientific, and Medical (902–928 MHz) band. The thickness of the antenna is only 0.2 mm, which can be wrapped inside a capsule’s inner wall. By cutting meandered slots on the patch, using open-end slots on the ground, and utilizing two long arms, the proposed antenna obtains a significant size reduction. In the conformal form, the antenna volume measures only 66.7 mm3. A single-layer homogeneous muscle phantom box is used for the initial design and optimization with parametric studies. The effect of the internal components inside a capsule is discussed in analyzing the antenna’s performance and to realize a more practical scenario. In addition, a realistic human body model in a Remcom XFdtd simulation environment is considered to evaluate the antenna characteristics and CP purity, and to specify the specific absorption rate limit in different organs along the gastrointestinal tract. The performance of the proposed antenna is experimentally validated by using a minced pork muscle phantom and by using an American Society for Testing and Materials phantom immersed in a liquid solution. For measurements, a new technique applying a printed 3-D capsule is devised. From simulations and measurements, we found that the impedance bandwidth of the proposed antenna is more than 20% and with a maximum simulated axial ratio bandwidth of around 29.2% in homogeneous tissue. Finally, a wireless communication link at a data rate of 78 Mb/s is calculated by employing link-budget analysis.

Size miniaturization of microstrip antenna embedded with open-ended ground slots

A compact rectangular microstrip antenna embedded with open-ended ground slots is presented in this paper. Three equal open-ended ground slots have been incorporated inside the ground plane in order to excite the antenna with a lower order resonant mode. On variation of the length parameter of the middle slot of the antenna, a resonant mode of lower order has been obtained near 1.52 GHz. The maximum size reduction of the designed structure is obtained, considering the lower band resonant frequency obtained is about 85.83% with a fractional bandwidth of 6.97%. The simple configuration has been fabricated on low-cost FR-4 substrate material. The proposed low-profile triple band microstrip patch obeys all the necessary standards prescribed for wireless communication and, therefore, finds its applicability in multiband wireless communication systems.

Compact Dual-Polarized Printed Slot Antenna

A dual-polarized printed slot antenna is constructed by inserting the open-end slot into the coplanar waveguide center conductor of T-shaped slot. In order to verify the antenna performance, an antenna prototype was fabricated. The experimental results show that its working bandwidth is about 10.5%. In the operating frequency band, the isolation between two ports is higher than 27 dB. The proposed two-port antenna has bidirectional radiation characteristics, but the gain of the T-shaped slot element is higher than that of the open-end slot element. In the maximum radiation direction, the copolarization level of the T-shaped slot is 39 dB higher than the cross polarization and 30 dB for the open-end slot. The proposed dual-polarized antenna has a compact structure.

CRLH Unit Cell Loaded Tri-Band Compact MIMO Antenna for WLAN/WiMAX Applications

A compact triple-band two-element multiple-input–multiple-output (MIMO) antenna is designed in this letter. The triple-band characteristic is achieved by loading a modified square-loop antenna with composite right/left-handed (CRLH) unit cell. Open-ended slot is etched from ground plane of the MIMO antenna to improve the isolation. The two-element antenna is well suited for WLAN/WiMAX applications as it covers 2.37–2.64, 3.39–3.58, and 4.86–6.98 GHz. Both envelope correlation coefficient and channel capacity loss are within their acceptable limits. Moreover, the antenna exhibits quasi-omnidirectional radiation pattern in x z -plane, which is useful for portable wireless communication devices.

Eccentric annular slot patch antenna with frequency agility for UHF RFID reader applications

The design of a simple ultrahigh frequency RFID (radio frequency identification) reader antenna that can operate within the North America RFID band (902–928 MHz) is studied. To generate circular polarization (CP) radiation in this band, a novel method of loading two narrow open-ended slots (slits) into an eccentric annular slot patch is proposed. To allow optimum impedance matching with enhanced CP bandwidth, the radiating patch is loaded to an L-shaped ground plane. From the experimental results, the proposed antenna can yield an impedance bandwidth (10-dB return loss) between 650 MHz to 1125 MHz, while good CP bandwidth (3-dB axial ratio, AR) from 901 MHz to 930 MHz is also attained. Furthermore, gain level and efficiency of more than 7.8 dBic and 90%, respectively, were also measured. By simply removing one of the slits, this proposed antenna can also be modified to operate within the China (840–846 MHz) and European (865–868 MHz) RFID band.

Magnetoelectric Dipole Antennas With Dual Open-Ended Slot Excitation

Designs of novel magnetoelectric dipole antennas excited by dual open-ended slots for both single and dual linear polarizations are presented in this paper. The antenna can be interpreted as a dual complementary source that exhibits lower profile and higher gain while maintaining excellent radiation characteristics of the original ME dipole, including wideband, low back radiation, and high polarization purity. In addition, high isolation is obtained in the dual polarization design. All the above characteristics show that the proposed antennas can be regarded as potential candidates for various wireless applications. Prototypes are fabricated and measured to confirm the simulation results.

Miniaturised dual‐band implantable antenna for wireless biotelemetry

A miniaturised implantable antenna with dual-band operation the Medical Implant Communications Service (MICS) (402–405 MHz) and Industrial, Scientific, and Medical (ISM) (2400.0–2483.5 MHz) bands is presented. The size of the proposed antenna is 31.5 mm3 (8.75 mm × 7.2 mm × 0.5 mm) which is the smallest size compared to previous implantable antennas. A serpentine-shaped radiating patch and open-end slot placed on the ground plane are used for miniaturisation. The performance of the antenna was evaluated from measurements and is based on good agreement with simulations.

Tri-Band CPW-Fed Stub-Loaded Slot Antenna Design for WLAN/WiMAX Applications

AbstractA novel uniplanar CPW-fed tri-band stub-loaded slot antenna is proposed for wireless local area network (WLAN) and worldwide interoperability for microwave access (WiMAX) applications. Dual resonant modes were effectively excited in the upper band by using two identical pairs of slot stubs and parasitic slots symmetrically along the arms of a traditional CPW-fed slot dipole, achieving a much wider bandwidth. The middle band was realized by the fundamental mode of the slot dipole. To obtain the lower band, two identical inverted-L-shaped open-ended slots were symmetrically etched in the ground plane. A prototype was fabricated and measured, showing that tri-band operation with 10-dB return loss bandwidths of 150 MHz from 2.375 to 2.525 GHz, 725 MHz from 3.075 to 3.8 GHz, and 1.9 GHz from 5.0 to 6.9 GHz has been achieved. Details of the antenna design as well as the measured and simulated results are presented and discussed.

Wideband Circularly Polarized Antenna With Stair-Shaped Dielectric Resonator and Open-Ended Slot Ground

A novel wideband circularly polarized (CP) antenna with a stair-shaped dielectric resonator and an open-ended slot ground is introduced. By adjusting parameter values of the hybrid structure, wideband CP characteristics can be realized. In order to improve the impedance matching and enhance the axial-ratio (AR) bandwidth, the open-ended slot is also inserted in the ground plane. The antenna is fully studied and manufactured. Measured results show that the proposed antenna has 10-dB return loss of 71.7% (3.844-8.146 GHz) and 3-dB AR bandwidths of 46.0% (4.15-6.63 GHz), respectively, and a peak gain of 3.9 dBic. In addition, more than 92% antenna radiation efficiency is obtained.

Minimum Lens Size Supporting the Leaky-Wave Nature of Slit Dipole Antenna at Terahertz Frequency

We designed a slit dipole antenna backed by an extended hemispherical silicon lens and investigated the minimum lens size in which the slit dipole antenna works as a leaky-wave antenna. The slit dipole antenna consists of a planar feeding structure, which is a center-fed and open-ended slot line. A slit dipole antenna backed by an extended hemispherical silicon lens is investigated over a frequency range from 0.2 to 0.4 THz with the center frequency at 0.3 THz. The numerical results show that the antenna gain responses exhibited an increased level of sensitivity to the lens size and increased linearly with increasing lens radius. The lens with the radius of 1.2λois found to be the best possible minimum lens size for a slit dipole antenna on an extended hemispherical silicon lens.

무선 Biotelemetry용 인체 이식형 안테나

This paper demonstrates a scalp-implantable miniaturized antenna at the medical implant communication service (MICS) (402–405MHz) band. The antenna size is only 27.63 mm3(8.5 mm × 6.5 mm × 0.5 mm), which is the smallest antenna for the MICS band. Miniaturization is achieved by using a symmetrical serpentine shaped radiating patch and placing open-end slots in the ground plane. In addition, co-axial feeding is used for excitation with a shorting pin connected between the radiator and ground. The antenna was simulated in a homogeneous skin model and in the human scalp. An experimental prototype of the proposed antenna was fabricated and measured in a skin-mimicking gel. Good agreement was obtained between the measurement and simulation results, showing a broad bandwidth of 49 MHz (from 395 to 444 MHz) for |S11| less than –10 dB and a maximum gain of -42.87 dBi. This gain is higher than the previous MICS antenna with respect to antenna size.

Design of compact dual-band co-axially fed microstrip antenna for 2.4/5.2/5.8 GHz WLAN applications

This paper presents a single-layer co-axial fed compact rectangular microstrip antenna for 2.4/5.2/5.8 GHz WLAN applications. The antenna consists of four rectangular and one triangular slot inside the patch and one rectangular open-ended slot inside the ground plane. Measured impedance bandwidths (2.36–2.485 and 5.14–6.43 GHz) show that the antenna is suitable for the applications in WLAN IEEE 802.11b/g and IEEE 802.11a bands.