Bidirectional Radiation Pattern Research Articles

A wideband and multibeam pattern reconfigurable antenna using partially reflecting surface

Abstract This paper presents a pattern reconfigurable antenna that accomplishes wideband and multibeam characteristics. The antenna design comprises a cross-slot radiator as the primary element and reconfigurable partially reflecting surface (PRS) layer placed above and below the cross-slot radiator. This configuration allows the antenna to adapt its radiation patterns effectively. The choice of the cross-slot radiator is based on its capability to offer wideband characteristics. The PRS layer consists of a precisely arranged array of 4×4 unit cells, incorporating PIN diodes into both the upper and lower PRS layers. The direction of radiation pattern can be changed by altering operating states of the PIN diodes on the PRS layer. The antenna operates in three distinct states, each exhibiting a unique radiation pattern. The antenna produces broadside, backward, and bidirectional radiation patterns. It demonstrates effective pattern reconfigurability across the frequency range of 3.10–3.86 GHz (21.71%), with a peak gain of 9.60 dBi. The simulated and measured results of the antenna are found to be in good agreement.

Compact Defected Ground Structure Microstrip Patch Antenna for Wi-Fi Applications

In recent years microstrip patch antennas having minute size is an exciting topic for many researchers and design engineers. In this paper a novel miniaturized microstrip patch antenna for Wi-Fi applications is proposed. The concept of defected ground plane (DGS) is used for achieving miniaturization. The prototype is designed and analyzed by CST Microwave Studio. Low cost FR-4 substrate having thickness of 0.8 mm is used for the design of the antenna. The antenna is having compact size of 16 × 17 mm2. The simulated results demonstrate that the antenna has bandwidth of 2.02% (49 MHz) with -41.46 dB reflection coefficient at resonating frequency. The antenna has bidirectional radiation pattern. The proposed design provides a size reduction of 75.46% in comparison to conventional patch. The proposed antenna is having compact size and is low cost which makes it a suitable candidate for 2.4 GHz Wi-Fi band.

Normal‐mode planar meander‐line antenna array with bidirectional broadside radiation pattern

AbstractIn this letter, a normal‐mode planar bidirectional broadside antenna array with the merits of high gain, broadband, low aerodynamic drag, and high assembly robustness is proposed. First, the bidirectional antenna array is implemented based on a novel design strategy. The expected radiation field generated by currents along the same direction is superimposed while the unexpected radiation field is offset due to the out‐of‐phase currents, achieving a normal‐mode high‐gain bidirectional pattern. Then, the bidirectional antenna array is designed with two metallic meander lines, featuring low aerodynamic drag and cost‐efficiency. Moreover, a simple feed structure using an impedance transformer parallel strip line is adopted for a wide bandwidth. Besides, the bidirectional antenna array exhibits a stable impedance when the array scale increases. The stable impedance is also observed when the antenna array is bent to different angles, ensuring ease of installation and high assembly robustness. To validate the design strategy, a prototype with an aperture length of 5.8λ at 2.4 GHz is fabricated. The proposed antenna array is designed to operate from 2.2 to 2.6 GHz, with a maximum gain of 13 dBi around the center of frequency, which can be a promising candidate in long and narrow communication scenarios.

Design of a Compact, Planar, Wideband, Overlapped, Bow-Tie Antenna in a Single Layer with Stable Bi-Directional Radiation Patterns

In this paper, a planar, bow-tie antenna with an enhanced bandwidth and a bi-directional radiation pattern is proposed. The concept of multi-resonance is applied by implementing the superposition of three different bow-tie components with various radii and flare angles in an overlapped fashion into a single element, resulting in a significant increase in bandwidth. The antenna has an electrical size, kr, of 1.10, calculated at the lowest frequency of operation. The proposed antenna is simulated, and a prototype is fabricated for verification by measurement. The result is a wide −10 dB bandwidth of 80.3% (1.23–2.88 GHz) from the measurements. The antenna also maintains a bi-directional radiation pattern, with a negligible difference between the forward and backward realized gains, within the entire −10 dB bandwidth. The measured realized gain values in the forward and backward directions are between 1.5 dBi and 3.7 dBi over the −10 dB bandwidth. The comparison of the measurement and simulation results shows good agreement.

Compact narrow slot antenna with stable radiation pattern and wide bandwidth

One of the most crucial parameters for any antenna is bandwidth. Over the whole extended bandwidth, the antenna achieves a high gain of 5dBi and a steady bidirectional radiation pattern. A novel design concept for increasing bandwidth and maintaining a consistent radiation pattern has been proposed for the radiated fields of a slot antenna. First, the radiated fields of the standard slot antenna are examined theoretically using characteristic modes (CMs). Its three CMs vibrate at 2.45, 4.78, and 7.17 GHz, respectively, according to the results. CM1 and CM3 both continue to emit radiation in both directions, but CM2 generates a radiation null in the broadside direction. After that, the linear slot is appropriately folded to change CM2’s non-bidirectional pattern into a bidirectional one, allowing for the broad bandwidth use of the neighbouring CM1 and CM2. The narrow slot is then used to create the stepped scheme, which reallocates these dual modes in close proximity to one another. By using these designs, the antenna’s radiation pattern consistency and small size of 0.022λo can be preserved, but its impedance bandwidth can be significantly expanded. After that, the proposed antenna is constructed and assessed. Measurements show that the antenna has a broad bandwidth (|S11|<−10 dB) of around 35.14%, covering the frequency range of 3.3 to 4.6 GHz.

Reconfigurable Antenna With Uni- and Bidirectional Radiation Patterns Based on Metasurface and Fresnel Zone Plate Lens

Reconfigurable Antenna With Uni- and Bidirectional Radiation Patterns Based on Metasurface and Fresnel Zone Plate Lens

Design of a low-profile bi-directional radiated Fabry-Perot cavity antenna with independent forward and backward radiation based on metasurface technique.

This paper introduces a novel Fabry-Perot cavity (FPC) antenna design based on metasurface technique to achieve bi-directional radiation with independent forward and backward beam control capability and a low-profile configuration. Two pieces of partially reflective metasurface (PRMS) based on receiver-transmitter architecture with independent control of transmission and reflection phases are designed to serve as the upper and lower layers of the FPC antenna, respectively. By manipulating the transmission phase distribution of the two pieces of PRMS, designable independent multi-beam bi-directional radiation patterns can be achieved. For validation, two FPC antennas based on the proposed configuration are designed with different bi-directional radiation patterns. Proved by simulated results, Antenna 1 can achieve forward dual-beam and backward single-beam radiation simultaneously with a return loss of less than -10 dB at 10.4 GHz. The two beams of forward radiation point in the -45° and 35° directions, respectively, with gains of 7.42 dBi and 7.70 dBi. The gain of the single beam of backward radiation is 10.82 dBi. Antenna 2 can achieve a four-beam radiation pattern with both forward and backward dual beams. The beam directions of the four beams are -153°, -44°, 37°, and 146°, respectively. The gains in each direction are 5.45 dBi, 6.63 dBi, 5.97 dBi, and 5.22 dBi, respectively. The overall profile is 23.72 mm (0.81 λ) for both antennas. The prototype of Antenna 1 is fabricated and measured. The results are in good agreement with the simulated counterparts, which demonstrates the feasibility of the proposed design methodology.

A Low-Profile Electrically Small Serrated Rectangular Patch Antenna for RFID Applications

This paper presents the design and analysis of a global system for mobile communication applications, as well as the design and analysis of a compact, bidirectional Electrically Small Antenna (ESA) at 0.9 GHz for Radio Frequency Identification (RFID) applications. In order to attain results at lower frequencies while keeping a compact size, the proposed design consists of a microstrip patch antenna in which an SRR and a semicircular-shaped SRR were subtracted from the ground plane. The dimensions of the FR4 substrate, on which this ESA was designed, were 20 × 18 × 1.6 mm. Ansys HFSS was used for the design and simulation of the antenna. Chemical etching was implemented to fabricate the ESA and MS2037C Anritsu Combinational Analyzer was applied for testing. The simulated results show that at 0.9 GHz, the ESA achieves a bandwidth of 300 MHz (700 MHz-1000 MHz). At the resonance frequency, a bidirectional radiation pattern with a 80% radiation efficiency is obtained in both H and E planes. A 90% agreement between the simulated and the fabricated results has been achieved.

Gain enhancement of ultra-wideband hexagonal slot antenna using tessellated rhombic loops based reflector

Abstract A simple technique for gain enhancement of irregular hexagonal shaped ultra-wide band (UWB) slot antenna by inclusion of closely packed tessellated rhombic loop (TRL) based FSS is presented in this paper. The slot antenna is designed to cover entire UWB (3.1–10.6 GHz) frequency range with stable bi-directional radiation pattern. Also, it exhibits non-uniform boresight gain in zenith (θ = 0°) and nadir (θ = 180°) directions. The slot antenna is further loaded with TRL FSS at both slot and feed side separately to study distinct configurations of antenna integrated with FSS and evaluate the impact of the configurations of FSS on antenna performance. Later, an antenna and antenna loaded with TRL FSS prototype are developed for experimental validations. Through measurements it is found that the slot antenna covers entire UWB frequency band and provides a maximum of 4.31 dB gain in zenith direction while 4 dB gain in nadir direction. A gain enhancement of 2.44 dB in zenith and 3.8 dB in nadir directions are achieved when the slot antenna is integrated with TRL FSS along feed side and slot side separately. The measured results confirm the simulated results well.

Analysis of a Compact Electrically Small Antenna with SRR for RFID Applications

This paper contains the design and analysis of a compact, bidirectional Electrically Small Antenna (ESA) at 0.9 GHz for Radio Frequency Identification (RFID) and a global system for mobile communication applications. The proposed design consists of a microstrip patch antenna enclosed inside the split ring resonators, in which a split ring resonator was subtracted from the ground plane in order to obtain the results at lower frequencies by maintaining a compact size. This ESA was designed on FR4 substrate having a dimension of 30 mm × 30 mm × 1.6 mm. This antenna was created and simulated with the Ansys HFSS. The ESA was fabricated by chemical etching and it was measured with the MS2037C Anritsu Combinational Analyzer. The simulated results show that the ESA attains a bandwidth of 100 MHz (with S11 &lt; -10 dB) at 0.9 GHz. The bidirectional radiation pattern in both H and E planes with a radiation efficiency of 80% at the resonant frequency was obtained. A close agreement of 90% between the simulated and the measured results was observed.

A compact high‐gain slot antenna array with a bidirectional broadside radiation pattern

AbstractA novel bidirectional broadside slot antenna array is proposed in this letter. The outstanding merits of this antenna array lie in the minimum width and the highest gain‐to‐area ratio (G/A) compared to previous works. The ingenious combination of the radiation mode and the transmission mode of slots is adopted, eliminating the design of the feed network. Thus, a simple and compact configuration is obtained. Moreover, two metal plates are added vertically at the sides of the slot array, with a more homogeneous radiation aperture and a higher G/A. With the 3D structure, a compact volume of the antenna array is ensured. For performance evaluation, our proof‐of‐concept design is fabricated with a cuboid dimension of 1.94λ0 × 0.12λ0 × 0.12λ0, where λ0 denotes the wavelength in free space at the centre frequency. An impedance bandwidth of 2.38 to 2.49 GHz is achieved, with a maximum gain of 9.7 dBi and a higher G/A of 39.5. The advantages including compact size and high G/A are paving the path for the potential application of communications in long and narrow spaces.

Bidirectional circularly polarized antenna with defected ground structure for wideband operation

The present work proposes a wideband circularly polarized antenna with novel design to cover the operation over most of the X-band of the microwave frequencies. This antenna is planar and printed on very thin and flexible Rogers’ substrate of material RO3003 with thickness 0.13mm. The antenna structure can be viewed as composed of an elliptic open annular strip that works as the main radiator. Two symmetric parasitic elements of elliptic arc-shaped narrow strips are capacitively coupled to the elliptic strip radiator. The feeding line is coplanar waveguide with defected ground structure. The parasitic elements and the defects on the ground structures help to enhance the bandwidth of both impedance matching and circular polarization. The antenna is designed to produce bidirectional radiation patterns with opposite sense of circular polarization. The design stages to arrive at the final design of the proposed antenna are described in detail. The antenna is fabricated for experimental assessment showing high performance regarding the circular polarization, bandwidth, and efficiency. The proposed antenna has total dimensions of 30×40×0.13mm3. Both the simulation and experimental results show that the antenna impedance is matched to 50Ω over the frequency band 7.5-13.0(54%bandwidth) and the axial ratio is lower than 3 dB over the frequency band 8.85-12.35GHz(33 % bandwidth). It is shown that the antenna gain ranges from 4.5 to 5 dBi, the radiation efficiency is greater than 99 % and the total efficiency is greater than 91 % over the entire frequency band of the proposed antenna.

Metamaterial based AMC backed archimedean spiral antenna for in-vitro microwave hyperthermia of skin cancer

ABSTRACT This research article presents a study that uses microwave frequencies (ISM band) for treatment of skin cancer by heating the malignant cells on skin with a Microwave Hyperthermia (MWHT) applicator. The proposed MWHT applicator has been designed as an Archimedean Spiral Microstrip Patch Antenna (AMSPA) of dimensions 38 × 38 × 1.64 mm3 backed with a Meshed-shaped AMC (48 × 48 × 3.27mm3) reflector, placed at an optimized distance of 12 mm from AMSPA. The proposed AMSPA is designed as a single spiral resonator and fabricated on FR-4 substrate, excited using a feed network. The proposed AMSPA shows a resonance at 2.5 GHz with an impedance BW of 260 MHz (2.37–2.63 GHz) and peak gain of 3.20 dB with a bidirectional radiation pattern. An AMC is placed at its backside that can be exploited as a phase-compensation surface to attain an in-phase profile for directive emission and improve the BW upto 470 MHz, peak gain to 6.8 dB and also enhance the front-to-back ratio of the radiating antenna with radiation efficiency of 80%. The simulated environment for hyperthermia analysis is set up using penne’s Bio-Heat equations to deliver microwave energy to the bio-mimic, that leads to a rise in temperature over the designed bio-mimic in CST MWS in the range of 41–45°C. The validation of MWHT radiation properties and temperature rise inside the malignancy of phantom is carried out by fabricating the bio-mimic using gelatine, vegetable oils and glycerol. This set up enhances the penetration-depth of EM waves inside the tri-layered phantom up-to 29.5 mm with Effective Field Surface of 36 × 36 mm2 and SAR of 8 W/Kg.

Low-Cost L-Band to Ku-Band Frequency Reconfigurable BAR64-02V Controlled Antenna for Satellite, Military, and Radar Applications

A miniaturized edge-fed multi-band wideband (WB) sensor complementary split ring resonator (CSRR) and two folded pedal arms loaded antenna for wireless, ISM, military, Radar, and satellite applications is fabricated, tested, and investigated. The reduced ground plane at the bottom to makes the gain positive and leads to improvement in the radiation efficiency. Loading of antenna patch with two folded bicycle pedal-shaped arms results in an increased total electrical length and hence antenna could be tuned up to higher frequency bands. The appended two folded pedal arms enhance the value of gain and CSRR loading introduces additional resonant frequencies below −10dB reflection coefficient. The symmetrical ground width compression results in total antenna size miniaturization to 43.33% concerning the conventional circular microstrip antenna designed at a frequency of 2.45GHz. The antenna has a bidirectional radiation pattern with a gain of 5.21dBi and a radiation efficiency of 90.50%. The antenna exhibits four bands (2.13–2.58GHz), (2.77–3.89GHz), (5.65–6.56GHz), and (7.77–12.98GHz) within a frequency sweep of 1–15GHz, therefore it, is the most suitable element for Bluetooth, PCS, ISM band, 3G/4G/5G, Wi-MAX/WLAN/ Wi-Fi, and wireless, satellite, military, and RADAR applications. These bands are frequency reconfigured by two BAP64-02V PIN diodes in the pedal-arms fold locations with four switching combinations. The measured (frequency sweep: 1–23GHz) and simulated antenna reflection coefficient values are found in match except for a frequency range of 12–14 GHz. The antenna was fabricated on a low-cost FR-4 that holds well <12 GHz frequencies, and >12 GHz frequencies values this shows nonlinear and frequency dispersion.

Investigation of the nonlinearity of PIN diode on frequency reconfigurable patch antenna

AbstractIn this work, the nonlinearity of PIN diode on frequency reconfigurable patch antenna is investigated. To perform frequency reconfiguration, the proposed design makes use of the switching capabilities of a PIN diode. The antenna has a dimension of 41 × 44 mm2 corresponding to 0.33 λ0 × 0.35 λ0, where λ0 represents the wavelength in free space at 2.4 GHz fabricated on Rogers Duroid RO3003TM material. In the OFF state of the PIN diode, a single resonance (ISM 5.8 GHz) is achieved. However, in the ON state of the PIN diode, a dual‐resonance (ISM 5.8 GHz and 2.4 GHz) is achieved. A directional and bidirectional radiation pattern can be observed in the E‐plane at 5.8 GHz and 2.4 GHz, respectively, and omnidirectional radiation patterns can be viewed in the H‐plane for both 5.8 GHz and 2.4 GHz. The gain is measured to be 4.84 dBi at 2.4 GHz and 5.87 dBi at 5.8 GHz, with total efficiencies of 91.8% and 92.5% at 5.8 GHz and 2.4 GHz, respectively. Two‐tone nonlinear measurements at 2.4 GHz and 5.8 GHz are used to evaluate the PIN diode. Several third‐order intermodulation distortion products (IMD3) frequencies are observed with input powers between 0 and 20 dBm. The IMD3 at 2.4 GHz is −36.18 dBm, while at 5.8 GHz is −47.19 dBm and the third‐order input intercept point (IIP3) of +66.65 dBm is obtained at 2.4 GHz, while +22.69 dBm at 5.8 GHz. Additionally, at 2.4 GHz, the 1‐dB gain compression (P1‐dB) could not be identified, showing that the antenna behaves linearly within the spectrum of input power. Similarly, the P1‐dB is detected at 14.8 dBm input power at 5.8 GHz. The proposed antenna works in the linear region up to an input power level of 15 dBm, where the received signal strength of the IMD3 is minimal, according to the measurement of the nonlinearity caused by the PIN diode. The nonlinearity results confirm that the active reconfigurable antenna designed and implemented in this work is suitable for use in the 2.4 GHz and 5.8 GHz bands for indoor and short‐range communication applications. Furthermore, the assessment of nonlinearity provides a deeper understanding of and helps mitigate the negative effects of nonlinearity on the proposed antenna. This measurement assists in refining biasing, selecting suitable linearization methods, improving the design, and evaluating performance at the system level. Ultimately, it enhances antenna performance and expands frequency reconfigurability by enabling optimization across multiple aspects.

English

In this paper, a pentagon-shaped slotted monopole antenna for WIFI6E applications based on a partial ground structure is designed, and its performance is evaluated. The pentagon-shaped slotted antenna has a dimension of 44 × 36 × 1.6 mm3 and exhibits good radiation characteristics most suitable for wifi6E applications. The designed structure is fabricated on FR4 high dielectric substrate material to evaluate the antenna characteristics. Four arc slots are removed from the pentagon patch to resonate at wideband frequencies. Simulation has been done in ANSYS HFSS SOFTWARE 19v. A peak gain of 6.2 dBi is attained by the pentagon-shaped slotted antenna, and the antenna produces a bi-directional radiation pattern.

Highly Compact 4 × 4 Flower-Shaped MIMO Antenna for Wideband Communications

This paper introduces an MIMO antenna with a highly compact size of 30 mm width and 30 mm length. Four symmetrical MIMO antenna radiators are utilized with decoupling stubs in the top and bottom planes of the substrate to improve the isolation level. The simulated and measured outcomes are validated to investigate the impact of the suggested MIMO antenna for wideband applications. The suggested MIMO antenna has an impedance matching less than −10 dB from 5.8 GHz up to 11 GHz, and the isolation between the four radiators exceeds 20 dB over this band. Moreover, the antenna provides an envelope correlation coefficient not exceeding 0.004, a diversity gain above 9.97 dB, and a mean effective gain of ≤−3 dB over the achieved frequency range. The suggested MIMO antenna exhibits a nearly omnidirectional radiation pattern in one plane and a bi-directional radiation pattern in the other plane with an acceptable average value of the realized gain (4 dBi) over the achieved frequency band. A comparison with the state-of-the-art is tabulated to show the distinct performance of the suggested MIMO antenna for wideband applications.

Design of an axial mode helical antenna with buffer layer for underwater applications

&lt;span lang="EN-US"&gt;Recently, there is an increasing demand for high-speed wireless communication network for short-range underwater communication. From previous research, most underwater antennas produced omnidirectional radiation pattern which has lower antenna gain. There are a few considerations that need to be taken if the antenna is designed to operate in water environment. This paper discusses the electromagnetic properties which affect the underwater antenna design. Physical properties such as electrical permittivity and conductivity of water contribute significant effect to the size of the antenna as it influences the behavior of electromagnetic signal that propagates in water. In this study, an axial mode helical antenna with waterproof container is presented which operates at 433 MHz. The axial mode helical antenna has circular polarization and is suitable to support wireless application which is surrounded by some obstruction. The proposed antenna produces a bidirectional radiation pattern by placing it into a waterproof casing. Good agreement between the simulation and measurement results validates the concept. However, a little discrepancy between the simulated and measured results may be attributed to the noise originated from the equipment and the environment.&lt;/span&gt;

Design and Analysis of a Compact Dual-Band Wearable Antenna for WBAN Applications

The design and analysis of a compact dual-band wearable antenna for WBAN applications is presented. The antenna was prototyped on a semi-flexible Rogers Duroid RO3003™ with compact dimensions of 41 × 44 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> which corresponds to 0.33 λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> × 0.35 λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> , where λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> is the free space wavelength at 2.4 GHz. The antenna is designed in the preliminary stage to resonate at 5.8 GHz. An inverted U-shaped slot is added to the patch to create one more resonant frequency at 2.4 GHz. In order to enhance the antenna’s bandwidth and gain, two slots at the patch’s bottom edge and a partial ground are added. The measured percentage of impedance bandwidth at 2.4 GHz and 5.8 GHz are 3.75% and 5.17%, respectively. The gain is measured to be 3.74 dBi and 5.13 dBi and the efficiency is 91.4% and 92.3%, respectively at the operating bands. The measured radiation patterns exhibit a bidirectional and directional radiation pattern in the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">E</i> -plane at 2.4 GHz and 5.8 GHz bands, while omnidirectional radiation patterns are observed in the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">H</i> -plane. At 2.4 GHz, the SAR limits are simulated to be 0.955 W/kg and 0.571 W/kg for 1 g and 10 g of human tissue, while at 5.8 GHz, the SAR limits are 0.478 W/kg and 0.127 W/kg, respectively. Therefore, the proposed antenna has met the FCC and ICNIRP standards. Bending conditions and on-body measurements of the proposed antenna indicate that the antenna’s performance is unaffected. As a result, it is shown that the antenna possessed the ability to be utilized in WBAN applications.

Design of miniaturized tri‐band antenna based on differential evolution algorithm

AbstractA novel highly miniaturized triple band structure based on Z‐slots‐shaped antenna is presented in this letter, with only 0.0015 footprint, where is the free space wavelength at 1.3 GHz. The proposed design can generates three resonant frequency bands (1.3–1.62 GHz), (2.22–2.59 GHz), and (3.24–3.65 GHz) with −10 dB reflection coefficient, a triple band function is achieved by etching tow connected Z‐shaped‐slots in the radiating element and the differential evolution algorithm is then used to control the currents path, the prototype of the proposed antenna is printed on a single substrate layer and fed via coplanar waveguide CPW technology. The measured and simulated results are in good agreement, and validate the design principle, the results show that the antenna has a compact size (19.5 × 17.6 mm2), aside from its planar design, simple manufacturing, and low cost to fabricate, this antenna exhibits stable omnidirectional radiation patterns in E plane as well as bidirectional radiation patterns in H plane, making it an ideal device for multiband applications.