Ultra-wideband (UWB) antennas with wide rectangular notched-band are proposed in this paper. The rectangular notched-band design is realized by placing dual mushroom-type electromagnetic-bandgap (EBG) structures on the CPW feeding line. The patches of the EBGs are laid on the back size of the substrate and dead against the CPW feeding line. Shorting pins are utilized to connect the patch and the feeding line. Then, the CPW feeding line operates as ground plane for the EBGs. By tuning the two resonant frequencies of the EBG structures and making them merge with each other, a rectangular notchedband is achieved. Research also found that design methodology has the ability to tune the width and the frequency of the rectangular notched-band by adjusting the EBG parameters. Then, three cases of rectangular notchedband designs to reject the wireless local-area network (WLAN, 5.150-5.825 GHz) interference band and the X -band downlink satellite communication band (660 MHz, 7.10-7.76 GHz) were designed by using different EBG parameters. The design methodology can also be utilized to design rectangular notchedband for other interference bands efficiently.

CPW Fed UWB Antenna by EBGs With Wide Rectangular Notched-Band

This paper introduces a novel MIMO UWB antenna with dual notches. The proposedantenna is based on Quasi Self Complementary (QSC) method to give wide impedance bandwidthfrom 2.4GHz to more than 12 GHz. The proposed antenna consists of a semi-elliptical patch that isfed by a tapered microstrip line. The antenna is designed on an FR-4 substrate with compact size20mm × 15mm × 1.5mm. The dual notched bands are achieved by using a square ring printed on thebottom of the substrate to reject WiMAX at 3.6 GHz. Also, a C-shaped slot is etched in the radiatingpatch to reject interference with the WLAN band at 5.8 GHz. In the proposed MIMO antenna, theisolation reduction is achieved utilizing diversity technique to minimize the mutual coupling betweenthe antennas. The isolation between MIMO elements is more than 20 dB. The envelope correlationcoefficient (ECC), diversity gain (DG), total active reflection coefficient (TARC), furthermore, channelcapacity loss (CCL) are measured and calculated. The proposed antenna is designed, simulated, andmeasured. A good agreement is shown between the experimental and simulated results.

https://www.jpier.org/pierc/pierc93/10.19031202.pdf

Planar UWB MIMO-Diversity Antenna with Dual Notch Characteristics

Bowtie antennas are ubiquitous in practical ground-penetrating radars. In spite of having a wide impedance bandwidth, boresight gain of these antennas is small and the main beam gets tilted beyond a 4:1 bandwidth. In this paper, a bowtie antenna design is presented, which has a return loss of at least 10 dB from 420 MHz to 5.5 GHz (13:1 bandwidth) and a stable radiation pattern and improved gain throughout the bandwidth. A superwide bandwidth is obtained without any kind of dissipative loading. The peak gain and average gain are 7.96 and 5.89 dBi, respectively. The gain of the antenna is improved using parasitic loops as directors. The size of the antenna is only $0.322\lambda $ at 420 MHz.

A Novel Compact Superwideband Bowtie Antenna for 420 MHz to 5.5 GHz Operation

A novel pattern reconfigurable planar optically controlled Yagi-Uda antenna is proposed. The antenna comprises a director, a driven dipole, a reflector and the substrate. The two parasitic elements loaded with positive intrinsic negative (PIN) photodiodes in the middle, applied as manipulating switches, are capable of varying the radiation pattern by transforming their physical structures. A prototype of the proposed antenna along with PIN photodiodes was fabricated to verify the concept of optically controlled pattern reconfiguration. The simulated and experimental results indicate that the |S
 11
| curves and radiation patterns of the proposed antenna in both the PIN switches' on and off state are similar; however, the direction of maximum radiation differs between these two states by 180°. Good unidirectional radiation patterns with the front-to-back ratios of 12 and 8 dB are obtained. About 10 dB impedance bandwidth can reach 15% and the maximum gain is more than 6.3 dBi. This study proposes a three-element equivalent current radiation model based on the current distribution from simulation, which can explain the directional radiation characteristics of the designed antenna well. This pattern reconfigurable antenna can be optically controlled remotely, reducing the effects of controlling network on the antenna radiator.

https://ietresearch.onlinelibrary.wiley.com/doi/pdf/10.1049/iet-map.2018.5204

Design and analysis of optically controlled pattern reconfigurable planar Yagi–Uda antenna

A method to realize low-cost, optically transparent, flexible, and unidirectional antennas is presented in this article. The key to the method is making a flexible transparent reflector made using a new method—injection of pure water into a flexible transparent cavity that is made out of polydimethylsiloxane (PDMS) polymer and integrating the flexible reflector with a flexible dipole made of transparent conducting mesh. This method is simple and inexpensive. Hence, it is useful for large-scale production of transparent, flexible, robust, and low-cost antennas as well as RF/microwave components for wearable body-area networks and other such systems that require flexible and transparent components. To validate the method, an antenna operating in the 2.45 GHz band was designed, fabricated, and tested under various conditions. Its measured gain is 3.2 dBi and efficiency is 51%. To the best of our knowledge, this is the first water-based transparent flexible antenna. Due to the shielding effect of the water-based reflector, it produces a low specific absorption rate (SAR) in the human body when it is worn, as expected from a unidirectional antenna. Furthermore, it is investigated and confirmed that the use of pure water in the reflector makes the antenna significantly more efficient as opposed to salt water.

/pdf/a-method-to-develop-flexible-robust-optically-transparent-nt16w9gmkn.pdf

A Method to Develop Flexible Robust Optically Transparent Unidirectional Antennas Utilizing Pure Water, PDMS, and Transparent Conductive Mesh

An uni-directional antenna designed by resonance-based reflector has the merits of compact size, low-profile, and ultra-wide impedance bandwidth. However, its front to back ratio (FBR) bandwidth is narrow owing to the small reflection coefficient values at the high frequencies of the RBR in-phase band. To solve this problem, a ring-shaped director (RD) was placed above a resonance-based reflector-based antenna to guide the high frequencies. Then, the FBR bandwidth was enhanced. The proposed antenna achieves a wide measured impedance bandwidth from 2.17 to 3.76 GHz (53.6%). Its FBR band (FBR >7 dB) covers the whole operational band and the FBR >10-dB band covers 2.17–2.58 GHz (17.3%). The proposed antenna consists of a bow-tie element, a ring-shaped resonance-based reflector under the bow-tie element and an RD above the bow-tie element to form a sandwich configuration. The profile of the proposed antenna is only $0.16~\lambda $ at the lowest frequency of 2.17 GHz. To further evaluate the performances of the proposed antenna, the time-domain characteristics of the antenna were analyzed in terms of group delay, waveform response, correlation coefficient, and pulsewidth stretch ratio. Good time-domain characteristics were observed.

Front to Back Ratio Bandwidth Enhancement of Resonance Based Reflector Antenna by Using a Ring-Shape Director and Its Time-Domain Analysis

In this research, the novel concept of a resonance-based reflector (RBR) was proposed, and a ring-shaped RBR was utilized to design a unidirectional antenna with low-profile and broadband characteristics. Research found the ring operates as two half-wavelength (λ/2) resonators. Then, the resonance effect transforms the reflection phase of the ring RBR, and achieves a reflection phase of 0° < ϕ < 180° in a wide frequency range above the resonance. Then, the in-phase reflection characteristic (−90° < ϕ < 90°) can be obtained in the wide frequency band by placing an antenna above the RBR with a distance smaller than λ/4. Two unidirectional antennas, named Case 1 and Case 2, were designed with the ring-shaped RBRs and bowtie antennas (RBR-BAs). The impedance bandwidths of Case 1 and the Case 2 are 2.04–5.12 GHz (86.3%) and 1.97–5.01 GHz (87.1%), respectively. The front-to-back ratio (FBR, an important parameter to measure the unidirectional radiation) of Case 1 ranges from 5–9.9 dB for frequencies 2.04–2.42 GHz, and the FBR of Case 2 ranges from 5–16 dB for frequencies 2.16–3.15 GHz. The proposed concept of RBR is desirable in wideband unidirectional antenna design, and the designing antennas can be used at the front end of wireless systems—such as indoors communication, remote sensing, and wireless sensor systems—for signal receiving or transmitting.

Resonance-Based Reflector and Its Application in Unidirectional Antenna with Low-Profile and Broadband Characteristics for Wireless Applications.

The invention discloses a zeroth-order resonator and a low-profile zeroth-order resonator omnidirectional circularly polarized antenna. The zero-order resonator is composed of a dielectric substrate, a metal patch, a metal floor and a short-circuit pin. The metal patch and the metal floor are respectively adhered on the two relatively parallel surfaces of the dielectric substrate. One end of the short-circuit pin is connected with the metal patch, and the other end is connected with the metal floor. The zeroth-order resonators are arranged at the external side of the radiation type feed network of the antenna in a surrounding way. Phase difference between two polarizations is enabled to be fixed at 90 degrees by the zeroth-order resonators, electric dipoles and magnetic dipoles are constructed by using a mode of circular ring group arrays, and the design of the zeroth-order resonator units and optimization of the circular ring array circularly polarized antenna are separated without considering the phase problem of two mutually perpendicular linear polarization components so that optimization efficiency can be enhanced, system resources can be saved and design efficiency can be enhanced. Besides, the designed omnidirectional circularly polarized antenna has the low-profile characteristic and can be applied to systems with the requirement for the antenna profile.

Zeroth-order resonator and low-profile zeroth-order resonator omnidirectional circularly polarized antenna

Abstract In this paper, a Bow-tie antenna with size reduction, impedance matching and radiation pattern improvement characteristics is designed with an encircling ring. Moreover, further size reduction is achieved by utilizing two symmetric split rings with more frequency tuning flexibility. Research found the ring loaded Bow-tie antenna (RLBA) shows better performance than the referenced Bow-tie antenna (RBA), and the mechanisms of performance improvements are also investigated and found to be the loading ring acts as two symmetric dipoles in the direction of the antenna’s polarization. Then, using two symmetric split rings on the opposite side of the substrate as replacement of the encircling ring will prolong the length of the dipoles, and achieves further size reduction. The antenna is denoted as dual split ring loaded Bow-tie antenna (DSRBA). The low cutoff frequencies of RBA, RLBA and DSRBA with identical antenna size are 2.65 GHz, 2.27 GHz and 2.06 GHz, respectively. Then, the corresponding diameters of the antennas are 0.353 λc, 0.303 λc, and 0.275 λc, where λc are their corresponding wavelength of the lower cutoff frequencies. Furthermore, a notched-band is generated as a byproduct of the split rings, and it is owing to the new resonance of the overlap areas of the split rings. The notch can be used to alleviate interference of WiMAX band by carefully choosing the split rings’ size. Radiation patterns of RLBA and DSRBA are also improved as current distributions of the high frequencies are trained in order by the ring/split-rings. Measurements are performed to verify the designs.

Investigation on Ring/Split-Ring Loaded Bow-Tie Antenna for Compactness and Notched-Band

Abstract Novel zeroth-order resonator (ZOR) composites epsilon-zero resonance (EZR) and mu-zero resonance (MZR) characteristics was proposed. The proposed resonator was constructed by moving via from centre of the conventional mushroom structure (CMS) to the edge, then, an edge-located via mushroom structure (ELV-MS) was formed. Thus, boundary conditions were transformed from all open-ended to half short-ended and half open-ended. Then, the new ZOR composites EZR and MZR characteristics (called EZR-MZR resonator). Owing to the unique characteristic of the composite EZR and MZR, the proposed ZOR antenna radiates both horizontal-polarized field (uni-directional) and vertical-polarized field (omni-directional). Then, wide half power beam width (HPBW) radiation patterns were realized for the antenna. The deduction and analysis of the proposed EZR-MZR resonator were conducted based on the composite right/left-handed transmission line (CRLH TL) and ZOR theories, and field distributions. The proposed ZOR antenna was investigated with two cases of coupling feeding.

Xie Jiyang

Papers

Front to Back Ratio Bandwidth Enhancement of Resonance Based Reflector Antenna by Using a Ring-Shape Director and Its Time-Domain Analysis

Resonance-Based Reflector and Its Application in Unidirectional Antenna with Low-Profile and Broadband Characteristics for Wireless Applications.

Zeroth-order resonator and low-profile zeroth-order resonator omnidirectional circularly polarized antenna

Investigation on Ring/Split-Ring Loaded Bow-Tie Antenna for Compactness and Notched-Band

Design and Analysis of a New ZOR Antenna with Wide Half Power Beam Width (HPBW) Characteristic