Proximity-coupled Feed Research Articles

A dual-band dual-sense circularly polarized patch antenna using hybrid capacitive-inductive proximity-coupling feed

This paper presents a new proximity-coupling mechanism between a rectangular patch and a microstrip line with an open circuit terminal. The patch is located to cover both adjacent maximum-voltage (capacitive coupling) and maximum-current (inductive coupling) points of the standing wave on the feedline, and consequently, two orthogonal resonant modes with 90° phase difference are excited on the patch for generating a circularly polarized (CP) radiation. Based on this feeding mechanism, a dual-band dual-sense CP antenna is designed, which is composed of two linear rectangular patch arrays coupled to an open-ending microstrip line. It is realized on a single-layer substrate and its CP rotating sense in each band is opposite to each other. For verification, the antenna operating at 5.0 and 8.0 GHz are designed, fabricated, and tested. Noting that the design concept can be easily implemented to other frequency bands. The measurements result in an impedance-matching bandwidth of 4.72 – 5.10 GHz and 7.50 – 8.20 GHz. The antenna is left-hand CP for the lower band and right-hand CP for the upper band. In addition, the prototype shows a 3-dB axial ratio bandwidth of 4.93 – 5.02 GHz and 7.40 – 8.10 GHz and peak gains of 11.4 and 12.7 dBic at the lower and upper bands, respectively.

Design and Optimization of a Mid-Field Wireless Power Transfer System for Enhanced Energy Transfer Efficiency

Mid-field wireless power transfer (WPT) offers a compelling solution for delivering power to miniature implantable medical devices deep within the human body. Despite its potential, the current power delivery levels remain constrained, and the design of a compact source structure to focus the transmitter field on such implants presents significant challenges. In this paper, a novel miniaturized transmitter antenna operating at 1.71 GHz is proposed. Leveraging the antenna proximity-coupled feeding technique, we achieve optimal current distribution for efficient power transfer. Additionally, a receiver integrated within the human body is proposed, comprising a slotted ground and a meandering slotted radiating element. This receiver is excited via a coaxial feedline with a truncated ground. Our findings demonstrate wireless power transfer of −23 dB (0.501%) at a distance of 30 mm between the transmitter and receiver, alongside a peak gain of −20 dB with an impedance bandwidth of 39.61%. These results highlight promising advancements in enhancing energy transfer efficiency for deep-implant applications.

A wideband 1 bit reconfigurable transmitarray antenna based on proximity-coupled feed patch element

ABSTRACT In this paper, a wideband 1-bit reconfigurable transmit array antenna (RTA) is proposed. The 1-bit RTA element consists of a passive receiving antenna and a reconfigurable radiating antenna, which adopt a proximity-coupled feed method to broaden the transmission bandwidth. Two p-i-n diodes are integrated into the reconfigurable receiving antenna to control the current distribution. By switching the states of the p-i-n diodes, the reconfigurable radiating antenna can achieve a 1-bit phase shift. Element simulation results show that the proposed RTA element can achieve a 3 dB transmission bandwidth of 21.5%. A 100-element RTA prototype with 200 p-in diodes is designed, fabricated and measured. The measured results show that the peak gain is 18.8 dBi at 5.05 GHz, corresponding to an aperture efficiency of 20.8%, and the 3 dB gain bandwidth is 17.1%. Furthermore, the scanned beams can reach −32° and −36°, respectively, in the E- and H-planes.

Analysis and Improvement of Bandwidth and Gain of Millimeter-Wave Microstrip Franklin Antenna With Proximity-Coupled Feed

Analysis and Improvement of Bandwidth and Gain of Millimeter-Wave Microstrip Franklin Antenna With Proximity-Coupled Feed

Design of Coplanar Proximity Coupled Feed Hexagonal Shaped Circular Polarized Microstrip Patch Antenna

This paper presents a broadband-multiband circularly polarized hexagonal patch antenna. The structure is fed by a unique coplanar hexagonal gap coupled proximity coupled feed with parasitic elements. The antenna is designed using a 14.2×14.2 mm2 FR4 substrate. By introducing hexagonal slot and I slot in the patch, the structure behaves as a multiband antenna with resonating frequencies at 2.76, 5.66 and 11.52 GHz. with 0.2837, 0.4525 and 0.3356 GHz respective bandwidths. By inserting I-shaped slots and rectangular slots in patch and also, I-shaped slots in the ground, the circular polarization is achieved in the L band and C band. The proposed structure was fabricated and tested. The simulated results of the magnitude of S11, radiation patterns and realized gains show good agreement with tested results.
 HIGHLIGHTS
 
 Proposed antenna is single layer broadband multiband circularly polarized hexagonal patch antenna
 A unique feed technique coplanar hexagonal gap coupled proximity coupled feed with parasitic elements is used
 The size of the antenna is compact 14.2×14.2 mm2 and resonating frequencies at 2.76, 5.66 and 11. 52 GHz. with 0.2837GHz/28.37%, 0.4525GHz/ 45.23% and 0.3356GHz/33.56%, respective bandwidths and efficiency
 The antenna is used for WiFi/WiMax application as well as terrestrial communication applications near the costal region or a high humidity environment
 
 GRAPHICAL ABSTRACT

Single-Element and MIMO Circularly Polarized Microstrip Antennas with Negligible Back Radiation for 5G Mid-Band Handsets.

In this paper, single-element and MIMO microstrip antenna with two pairs of unequal slits is proposed as a circularly polarized antenna with negligible back radiation for 5G mid-band handsets. The unequal pairs of slits are engraved on the antenna patch to guarantee the presence of the circular polarization (CP). The proximity-coupled feeding technique is used to excite the proposed microstrip antenna in order to provide larger antenna −10 dB bandwidth which approaches 10.8% (3.48–3.87 GHz). A novel analysis technique is proposed in this paper that demonstrates the 3D axial ratio pattern in order to generate CP in the broadside direction without affecting the structure of the ground plane which ensures weak back radiation. The 3 dB axial ratio bandwidth (ARBW) is found to be equal to 4.1% extended along the range (3.58–3.73 GHz). To make the design more compatible with the 5G mid-band handsets, the 2 × 2 MIMO structure of the proposed antenna with reduced mutual coupling (less than −20 dB) is also presented in this work. The simulation and measured results are in good agreement, and both verify the CP characteristics and the weak back radiation of the proposed antenna.

Performance Analysis and Development Of Printed Circuit Microstrip Patch Antenna with Proximity Coupled Feed at 4.3 GHz (C-band) with Linear Polarization for Altimeter Application

Performance Analysis and Development Of Printed Circuit Microstrip Patch Antenna with Proximity Coupled Feed at 4.3 GHz (C-band) with Linear Polarization for Altimeter Application

Low-Profile Broadband Vertically Polarized Microstrip Magnetic Dipole Antenna With Endfire Radiation

A low-profile broadband vertically polarized microstrip magnetic dipole antenna with endfire radiation is proposed for millimeter-wave (mmWave) applications. For the bandwidth enhancement, a lower resonance is introduced by the parasitic patches firstly. Then, a top-loaded circular probe and an inset proximity-coupled feed structure are employed for adjusting the resonances from the magnetic dipole antenna and the parasitic patches. In this way, a broad impedance bandwidth is attained. After that, a 1 × 4 antenna array prototype is designed, fabricated and tested. Experimental results demonstrate that the proposed array features an impedance bandwidth wider than 19% at 28 GHz mmWave frequency band under an ultralow-profile of 0.075 <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">λ</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> at the center frequency.

Design and Performance Study of Single and Multi-Layered Fractal Based Miniaturized Patch Antennas for 2.4 GHz Applications

The design and characterization of single and multi-layered miniaturized microstrip antennas resonating at 2.4 GHz are proposed. The miniaturization is accomplished by fractal Defected Ground Structure (DGS). The DGS used for miniaturization is a Modified Minkowski Fractal DGS (M-MFDGS). The proposed size reduction process with M-MFDGS follows the selection of the best antenna configuration and its design parameters through sensitivity analysis and pattern search optimization. Microstrip patch antennas with three different feeding mechanisms are considered here to validate the effect of DGS over the size reduction and performance improvement. Incorporating M-MFDGS in three antennas, the first one with microstrip line feed accomplishes a maximum patch area reduction of 70% among the three proposed structures with a gain of 1.43 dBi. Likewise, with a slightly higher dimension than the first structure, the second antenna with proximity-coupled feed achieves a higher gain (5.11 dBi) and bandwidth (110 MHz). Although the size reduction in the third antenna with aperture-coupled feed is a little less it has the highest gain (5.91 dBi) among all the three. All three compact antennas are physically fabricated and the simulated results are validated with the measured results.

An Analysis of Slot Dimension Changing in Dual band Rectangular Patch Microstrip Antenna with Proximity Coupled Feed

In this paper, the characteristics of dual band rectangular patch microstrip antenna using proximity couple feed are studied. It can be used for a wireless device that works on multiband frequency. The addition of slot and proximity feed used in order to obtain larger bandwidth and multiple frequency. Microstrip antenna is designed and simulated using software also used to analyze by changing the variable of microstrip slot’s dimension. The parameters are tested in this study include Voltage standing wave ratio (VSWR), return loss, gain, bandwidth and radiation patterns. From the simulation results, the best value of return loss antenna is -23,29 dB at 2,4 GHz with a slot width of 1 mm and 0,085 GHz bandwidth. At 3,7 GHz, the best value of return loss antenna is -23dB with a slot width of 2 mm and 0,12 GHz bandwidth. Afterwards, the best VSWR obtained on dual band microstrip antennas with proximity coupled feed is 1,14 and 5.53 dBi gain.Keywords: slot, bandwidth, proximity, return loss, gain.

Planar Feeding Techniques for Wearable Textile Antennas

Feeding techniques for textile antennas are of crucial importance to simultaneously address mechanical requirements of robustness while maintaining high RF performance. To assist in determining which planar feeding mechanism is best suited for textile antennas, a dedicated study of various planar feeding mechanisms is undertaken as one of the main aims of this article. Two of the most prominent techniques, namely the inset and proximity-coupled methods, are investigated on a quarter-wave patch, with particular attention to their suitability for various substrate thicknesses. It is shown that neither technique is suitable beyond a substrate thickness of $0.03\lambda _{0}$ . Consequently, a new textile feeding technique is proposed that blends aspects of the inset and proximity-coupled feeding techniques and represents the main contribution of this article. It is shown that this new feeding mechanism can serve as viable planar textile replacement for a coaxial probe feeding mechanism up to the substrate thicknesses of $0.05\lambda _{0}$ .

Point to Point Communication: 5.8 GHz Circular Polarized Proximity-Coupled Feeding Antenna

In this paper, point to point circular polarized 5.8 GHz patch antenna has successfully designed and simulated. This paper presented a design where both of the opposite edges of the rectangular patch of the antenna are truncated using proximity-coupled feeding technique. Both simulations of the proposed antennas had been analyzed. The objectives of this paper has been achieved which is to design and simulate the circular polarized antenna with operating frequency of 5.8 GHz. From the results, the proposed antennas with different feeding technique that radiate at a constant frequency showed some distinct value towards the size of the antenna and the characteristic of its radiation. The results indicate that the antenna that uses proximity-coupled feeding technique yields 3.551 dB directive gain, return loss and axial ratio at -10.015 and 2.225 dB respectively. Meanwhile, the directivity values for the antennas is 5.97 dBi. It can be conclude that by using proximity coupled fed technique, the gain of an antenna can be enhance thus increasing the antenna performance.

Design of a Frequency Reconfigurable Broadband THz Antenna Based on the Vanadium Dioxide

In this article, the design of a frequency reconfigurable broadband THz antenna based on vanadium dioxide (VO2) is investigated. Instead of being fed by the microstrip line directly, a windmill-shaped feeding structure is designed to provide a proximity-coupled feeding method. Many modes with contiguous resonant frequencies can be excited to obtain the wideband performance. The proposed antenna combines gold with metamaterial VO2. Thanks to insulator-metal phase transition characteristic of VO2 at phase transition temperature (68 °C), we can change the length of the resonant branches to realize frequency reconfiguration by changing the external temperature (T). The simulated results illustrate that when T = 50 °C (State I), such an antenna has a bandwidth of 35.2% (7.01–10 THz) with S11 below − 10 dB, and a maximum gain of 6.62 dBic. When T = 80 °C (State II), it has a bandwidth of 21.8% (5.77–7.18 THz) with S11 below − 10 dB, and a maximum gain of 4.49 dBic. Thus, we realize a design of a proximity-coupled antenna with reconfigurable wideband over the THz band.

On the Design of Patch Antenna Array

Abstract In this paper, a coaxial fed patch antenna array for application in the 2.4GHz ISM band was implemented using the Ansoft HFSS software. Standard formulas were used to calculate different parameters of the antenna. These were just used as a basis of design as some parameters varied considerably during simulation. A good extent of the antenna design was hence done through trial and error. The proposed antenna was designed to work at 2.44GHz frequency band. A fractional bandwidth of 2.62%, which was not close to the desired 10% and a reflection coefficient of -18.2131dB were attained. This may have been brought about by poor impedance matching and a high level of spurious feed radiation and surface waves. A way of improving the bandwidth would have been to use proximity coupling feeding method which offers the highest bandwidth (as high as 13%) and is somewhat easy to model and has low spurious radiation. However, its fabrication would have been more difficult. A directivity of 8.53dB was achieved. This was a fairly high though directivity increase could have been studied through use of different substrate material and thickness.

Review Design of Slot Antenna Based on Ansoft HFSS Software

Abstract In this paper, a micro-strip fed slot antenna array for application in the 2.4GHz industrial, scientific and medical(ISM) band is implemented using the Ansoft HFSS software. Standard formulas are used to calculate different antenna parameters. The proposed antenna is designed to work at 2.4GHz frequency band. A half power beam width(HPBW) of 57°. A bandwidth of around 7.7% is attained. This may have been brought about by poor impedance matching and a high level of surface waves. A way of improving the bandwidth would have been to use proximity coupling feeding method which offers the highest bandwidth and is somewhat easy to model and has low spurious radiation. However, its fabrication would have been more difficult. A directivity of 2.01 dB is achieved. This is a fairly high though directivity increase could have been studied through use of different substrate material and thickness. Adjusting length and width of narrow slot loop antenna will influence on the resonance frequency and bandwidth. By using HFSS software, the characteristics of antenna are investigated and analyzed, including voltage standing wave ratio (VSWR), return loss and far field radiation patterns.

Proximity‐coupled feed patch antenna array for 79 GHz automotive radar

Autonomous driving is becoming a reality-but low-cost 79 GHz radar antenna technology is still imperfect. Here, the authors propose a kind of proximity-coupled feed patch antenna array. By reducing the non-linear mutual interference between the transmission line and the radiating elements, the antenna's operating bandwidth is improved and the antenna gain is increased. Moreover, the consistency of the antenna radiation pattern at different frequencies is also improved. The simulation results show that the antenna has a −10 dB impedance bandwidth from 76 to 81.4 GHz, and the gain is >14.8 dB. Within the operating frequency band, the antenna main lobe width is smaller than ±1.2°

A Wide-Angle Circularly Polarized Tapered-Slit-Patch Antenna With a Compact Rectifier for Energy-Harvesting Systems [Antenna Applications Corner

A tapered-slit-patch antenna with wide-angle circularly polarized (CP) radiation and a compact rectifier was investigated for energy-harvesting systems. A tapered-slit octagonal-shaped patch radiator was implemented to realize the CP microstrip antenna with wide-angle radiation using a proximity-coupled feed. Eight tapered slits with length difference of 1.3% were embedded along the octagonal directions symmetrically on the microstrip radiator from the patch's center. The antenna prototype showed a gain of more than 5.8 dBic across the CP bandwidth of 7 MHz (894-901 MHz) with a 3-dB axial ratio (AR) beamwidth of more than 180°. A compact composite right/left-handed (CRLH)-based rectifier operating at 900 MHz was designed to be used along with the antenna for radio-frequency (RF) energy-harvesting system. A microstrip line forms the righthanded part of the CRLH transmission line (TL), and the lumped components form the left-handed part of the CRLH TL. The proposed rectifier was compact with size of 0.18λ 0 × 0.075λ 0 × 0.0002λ 0 at 900 MHz with a high RF-dc conversion efficiency of 43%.

A New Differentially-Fed Frequency Reconfigurable Antenna for WLAN and Sub-6GHz 5G Applications

A new differentially fed frequency reconfigurable antenna adopting proximity-coupling feeding for WLAN and sub-6-GHz 5G applications is proposed in this paper. It consists of two substrates that are separated by a 2.5-mm-thick air gap. By configuring the four p-i-n diode switches arranged on the two substrates, the excitation of the radiating patch and the length of the feed-lines can be controlled, and then, two different operating frequency bands can be obtained. The experiments indicate that the designed antenna can be switched between two states operating at 2.45- and 3.50-GHz band, respectively. Good agreement between the simulated and measured results is achieved, and the radiation patterns and gains are similar for the two states. The proposed antenna is a good candidate for WLAN (2.45 GHz) and sub-6-GHz 5G (3.50 GHz) applications.

A Novel Reconfigurable Microstrip Patch Antenna With Polarization Agility in Two Switchable Frequency Bands

A novel reconfigurable microstrip-fed patch antenna with polarization agility in either of two bands is proposed in this communication. Frequency reconfigurability is achieved by connecting an additional small patch to the main patch through a p-i-n diode. Each corner is cutoff from the main patch through a narrow L-shaped cut to get polarization reconfigurability. In addition, the impedance and axial ratio bandwidths are enhanced by using the proximity-coupled feed. Both prototypes are designed, fabricated, and tested. The measured results agree well with the simulated results in all cases. Also, the proposed microstrip-fed antenna is tested at high RF input power. The proposed structures are simple, low profile, low cost, and have simple bias circuitry. The proposed antennas are capable of operating in three polarization states, i.e., left-hand circular polarization, linear polarization, and right-hand circular polarization in two frequency bands. The proposed structures are best suited for modern advanced wireless communication systems such as LTE and 5G.

Cavity-Backed Proximity-Coupled Reconfigurable Microstrip Antenna With Agile Polarizations and Steerable Beams

A major challenge for a combined reconfigurable antenna is to realize both polarization switching and beam steering independently in a compact antenna structure. A cavity-backed proximity-coupled reconfigurable microstrip antenna proposed in this communication provides an efficient solution. Beam lead p-i-n diodes DSM8100-000 are employed as switching elements to achieve reconfiguration. Three different linear polarizations (0°, 45°, and 90°) are realized by switching the diodes on a proximity-coupled feed network. For each polarization state, the main beam can be steered to three directions by using a reconfigurable parasitic-element network. The parasitic-element network is printed on the same plane of the radiating patch, thereby making the antenna compact. This antenna has nine different working modes, and for all the working modes, the reflection coefficients are below -10 dB with the measured realized gains ranging from 7.2 to 8.1 dBi.