Annular-ring Slot Antenna Research Articles

Single-Layer, Dual-Port, and Dual-Mode Antenna With High Isolation for WBAN Communications

In this letter, a single-layer, dual-port, and dual-mode antenna with high isolation between the ports is suggested. This antenna consists of a short-circuited ring patch antenna that surrounds a substrate integrated waveguide (SIW)-based circular cavity in the center. An annular-ring slot is etched on the upper surface of the circular cavity and constitutes a cavity-backed annular ring slot antenna. Dimensions of the antenna are chosen in a way that TM₂₁ mode and TM₁₁ mode are placed at the frequency of 5.8 GHz for the short-circuited ring patch antenna and SIW cavity-backed antenna, respectively; the former has an omnidirectional radiation pattern and the latter has a broadside radiation pattern. Due to having two rows of vias, one for the short-circuited ring patch antenna and the other for SIW cavity-backed antenna, the isolation between the two ports is excellent owing to reduced surface waves. The measurement results of a fabricated prototype are properly consistent with the simulation results. This antenna is an appropriate option to be used in wireless body area networks for having simple structure, dual-mode, single-frequency, and high isolation.

Polarization reconfigurable annular ring slot antenna design

This paper proposes a simple polarization reconfigurable annular ring slot antenna (ARSA). The proposed ARSA is able to switch among three polarizations, i.e. left-handed circular polarization (LHCP), right-handed circular polarization (RHCP), and linear polarization (LP). The circular polarization (CP) property can be attained by introducing an appropriate inductance at a particular angle across the annular slot. In the design, two PIN diodes are incorporated to provide the required inductance, and at the same time the antenna polarization can be switched by controlling the state of the diodes. The simple design employs the parasitic inductance of the active elements, and hence eliminates the necessity of additional CP perturbation structures. The measured results show that all three polarizations exhibit good impedance matching. Excellent CP performance has been obtained for both circular polarizations with a 3-dB axial ratio (AR) bandwidth (BW) of roughly 6.0%.

Design and Analysis of Figure Eight Shaped Slot Antenna Array for Wideband Applications

An eight shaped annular ring slot antenna array is presented. Feed is designed with T shaped Power divider and quarterwave transformer is used. Antenna element is comprised of two linked annular slots to achieve high band width. Analysis is carried out with HFSS simulation software. Array is configured with corporate feed structure. It has been observed tha gain is increased to 4dB to 5dB and return loss band width increased from 600 MHz to 1.2 GHz around 55%, Cross polarization level also significantly decreased,

A Low Profile High Gain Ultra Lightweight Circularly Polarized Annular Ring Slot Antenna for Airborne and Airship Applications

In this paper a low profile circularly polarized annular ring slot antenna (CPARSA) with high gain is presented. An inverted U-shaped meandered slot is cut at the inner patch of annular ring to obtain the circularly polarized (CP) radiation. This annular slot loaded ground plane on a substrate thickness of 0.5 mm results in a very low profile (0.009λ 0 ) antenna in term of free space wavelength at its center operating frequency. The largest side lengths of octagonal shaped antenna are 0.89λ 0 × 0.89λ 0 according to its center frequency. Measured impedance bandwidth of 23.54% from 5.4 GHz - 7.0 GHz (for |S 11 | ≤ -10 dB) and AR bandwidth (AR<; 3 dB) of 5.15% from 5.67 GHz - 5.97 GHz are achieved by the antenna. Meanwhile, stable radiation pattern is observed throughout the entire bandwidth with peak gain of 7.6 dBi at the center frequency of 5.8 GHz. A defected ground plane is employed in the design which results in reduction of surface waves leading towards higher gain of antenna. The proposed antenna operating at 5.8 GHz band is fabricated on low cost substrate with standard printed circuit board (PCB) process. The proposed design provides favorable characteristics for various lightweight applications including miniaturized drones and airborne applications. To validate the prototype, measured results are compared with simulation outcomes and good agreement is obtained.

Wideband circular polarized Fabry-Perot cavity antennas for V-band indoor point-to-point communications

ABSTRACTIn this paper, a 60 GHz planar Fabry-Perot cavity (FPC) antenna with a circularly polarized (CP) radiation characteristic is proposed as a good candidate for millimeter-wave wireless systems. A sparse array design is employed to enhance the gain bandwidth (GBW) product of the antenna. Complete formulations for circular polarized radiation are developed to serve as a general guideline scalable to any frequencies. The theoretical results using ideal point sources are validated by numerical analysis using the finite elements method (FEM). In the full-wave simulations, the ideal sources are replaced by four annular-ring slot antennas to excite the FPC.

Dual-band capacitively loaded annular-ring slot antenna for dual-sense circular polarization

This paper investigates a simplified and new capacitively loaded annular-ring slot antenna (ARSA) for dual-band and dual-sense circular polarization. The antenna is comprised of two concentric annular-ring slots coupled to a microstrip feed line to achieve dual-band operation. With introducing proper distributed capacitances fulfilled by two closely spaced T-shaped arc strips across the outer and inner annular-ring slots at opposite positions with respect to the microstrip feed line, the dual-sense circular polarization can hence be obtained. The antenna features that the impedance and circular polarization characteristic for the upper band can be independently adjusted. Numerical analysis and experimental validation have been carried out. The measured 10-dB return loss impedance bandwidths for both bands are greater than 22.0%. The measured 3-dB axial ratio (AR) bandwidths are 3.6 and 5.6%, respectively, for the lower and upper bands.

Microstrip-line-fed reactively loaded circularly polarized annular-ring slot antenna

A simple and novel reactively loaded annular-ring slot antenna (ARSA) fed by a microstrip line is proposed and investigated for circularly polarized (CP) radiation. An appropriate reactive component, i.e. lumped capacitor/inductor, is introduced across the annular-ring slot at a proper position to achieve CP radiation. To validate the design concept, a capacitively loaded ARSA (CL-ARSA) and an inductively loaded ARSA (IL-ARSA) were implemented and measured, showing that good CP characteristics have been attained. The measured 3-dB axial ratio (AR) bandwidths for the CL-ARSA and IL-ARSA are 5.5 and 6.7%, respectively.

A novel single-feed reconfigurable antenna for polarization and frequency diversity

A novel dual-band single-feed reconfigurable annular-ring slot antenna with polarization diversity is proposed. This antenna has the ability to switch frequency bands and polarization at the same time whereas applying a simple structure. It consists of two concentric circular slots and two tuning stubs on one side of the substrate and a 50 Ω microstrip feed line and two stubs on the other side. The proposed antenna can be switched between two resonant frequencies, 2.4 GHz (WLAN) and 3.5 GHz (Wimax). Furthermore, it can be switched between linear polarization (LP), left-hand circular polarization (LHCP), and right-hand circular polarization (RHCP) at the first frequency band, LHCP and RHCP at the second band. All these capabilities are achieved by applying only five PIN diodes on both sides of the substrate. Simulation and experimental results indicate that the proposed antenna demonstrates a good impedance bandwidth at the two frequency bands and satisfactory radiation pattern in five different states.

Dual‐band, low‐profile, vertically polarized annular ring slot antenna embedded in a small metallic UAV

ABSTRACTA dual‐band, low‐profile, vertically‐polarized annular ring slot antenna is presented. The antenna consists of an annular ring slot structure and a ring‐shaped structure. The ring‐shaped structure is attached on the back of the annular ring slot structure using two sets of conductive vias to avoid increasing the size of the proposed antenna. Dual‐band characteristic is realized by adjusting the radius of the annular ring slot structure and the ring‐shaped structure. Analysis of the dual‐band characteristic of the proposed antenna is discussed. The proposed antenna is vertically polarized and provides a monopole‐like radiation pattern on both the frequency bands. The ground size of the proposed antenna is the same size as the antenna radius. The ground plane is relatively small comparing with most of the other vertically polarized patch antennas. The edge of the proposed antenna is shorted by a set of conductive vias. The proposed antenna is insensitive to the surrounding environment and thus can be embedded in a metallic unmanned aerial vehicles (UAV). A prototype with a height of 3.048 mm (0.03λ) and radius of 55 mm (0.45λ) is designed, fabricated, and measured. The proposed antenna works at 2.38 and 2.58 GHz. In addition, the proposed antenna embedded in a metallic UAV is simulated. The results show that the metallic UAV has small effect on the performance of the antenna. The proposed antenna is suitable for the operations of being controlled by a ground control station (GCS) and transmitting data to the GCS simultaneously for a small UAV. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:323–328, 2016

Compact SIW Annular Ring Slot Antenna With Multiband Multimode Characteristics

A substrate-integrated waveguide (SIW) cavity-backed annular ring slot antenna with multiband multimode characteristics is proposed in this communication. The antenna consists of an SIW cavity and an annular slot on top surface as the radiator. Two patch-like radiation patterns and one monopolar radiation pattern at three different frequencies are excited by the single fed antenna. Moreover, each operating frequency can be individually adjusted. A prototype is fabricated and measured to validate the theoretical analysis. Good agreement between the simulated and measured results of the input reflection coefficients and radiation patterns is achieved. Compared with other designs, the proposed antenna has features of simple structure, multiband multimode and frequency-tunable characteristics.

Annular ring slot antenna design with reconfigurable polarization

A microstrip-fed conventional annular ring slot (ARS) antenna with linear polarization (LP) is initially studied. To generate two orthogonal degenerate modes for circular polarization (CP) radiations, two identical meandering perturbation slots (MPS) are symmetrically loaded into the ARS. By further incorporating a PIN diode switch across each MPS, the proposed antenna can switch between left-hand CP (LHCP), right-hand CP (RHCP), and LP. All three polarizations have shown good impedance bandwidth and broad CP bandwidth that can satisfy the wireless local area network (WLAN) 2.4-GHz operating band (2400–2480 MHz). Furthermore, desirable gains of 1.8–2.0 dBi and 2.40–2.84 dBic are also exhibited at LP and LHCP/RHCP, respectively. © 2015 Wiley Periodicals, Inc. Int J RF and Microwave CAE 26:110–120, 2016.

Polarization Reconfigurable Eccentric Annular Ring Slot Antenna Design

A microstrip-fed reconfigurable eccentric annular ring slot (EARS) antenna with switchable polarization is proposed. To generate orthogonal circular polarization (CP) radiations, two identical perturbation slots (PSs) are loaded below the eccentric ring-shaped slot. By incorporating a PIN diode switch across each PS, the proposed antenna can switch between left-hand CP (LHCP), right-hand CP (RHCP), and linear polarization (LP). All three polarizations have shown good impedance bandwidth and broad CP bandwidth that can cover the WLAN 2.4 GHz operating band (2400–2480 MHz). Furthermore, desirable gains of 2.49–2.82 dBi and 2.94–3.24 dBic are also exhibited at LP and LHCP/RHCP, respectively.

Annular-ring slot antenna designs with circular polarization radiation

The design of a microstrip-fed annular-ring slot antenna (ARSA) with circular polarization (CP) radiation is initially studied. To obtain CP radiation with broad 3-dB axial ratio (AR) bandwidth that can cover the WiMAX 2.3 GHz (2305–2320 MHz, 2345–2360 MHz) and WLAN 2.4 GHz (2400–2480 MHz) bands, a novel technique of extending an inverted L-shaped slot from the bottom section of the annular-ring is proposed. To suppress the harmonic modes induced by the CP ARSA, the technique of integrating a defected ground structure into the annular-ring slot is further introduced. From the measured results, 10-dB impedance bandwidth and 3-dB AR bandwidth of 44.86 and 9.68% were achieved by the proposed harmonic suppressed CP ARSA. Furthermore, average gain and radiation efficiency of ∼4.7 dBic and 71%, respectively, were also exhibited across the bands of interest. © 2014 Wiley Periodicals, Inc. Int J RF and Microwave CAE 25:337–345, 2015.

A Frequency Reconfigurable Half Annular Ring Slot Antenna Design

The design of a switchable microstrip-fed half annular ring slot antenna for multi-frequency operation is proposed. By incorporating three switches along the meandered tuning stub that is loaded on top of the half circular patch located within the circular slot, easy reconfigurability of four frequency bands over a frequency ratio of approximately 1.7:1 can be achieved. Furthermore, the proposed antenna structure does not require additional DC biasing circuit. Simulation and measurement results have demonstrated that the four frequency bands can exhibit good impedance matching, stable radiation patterns and desirable gains.

MINIATURIZED ANNULAR RING SLOT ANTENNA FOR SMALL/MINI UAV APPLICATIONS

A miniaturized annular ring slot antenna is presented. The antenna consists of an annular ring slot structure and a novel folded matching structure. The annular ring slot structure is printed on a substrate and shorted concentrically with a set of conductive vias. The additional matching structure is a ring cavity attached to the back of the annular ring slot structure. Firstly, the diameter of the proposed antenna is reduced by using the folded matching structure comparing with traditional annular ring slot antennas. Secondly, the impedance matching of the proposed antenna is achieved by optimizing the size of the matching structure. A prototype of the proposed antenna with a height of 3.048 mm (0.03λ) and a radius of 47.2 mm (0.4λ) is designed, fabricated and measured. The antenna resonates at 2.67 GHz and has a monopole-like radiation pattern, which shows that the antenna is suitable for the applications of taking off, landing, and long distance communications for a small or mini UAV.

INTEGRATED COMPACT CIRCULAR POLARIZATION ANNULAR RING SLOT ANTENNA DESIGN FOR RFID READER

An integrated compact circular-polarized annular ring slot antenna is proposed in this paper. It consists of an annular ring slot radiator and a hybrid patch coupler. The hybrid patch coupler is integrated with the annular ring slot antenna to radiate the circular- polarized wave, while size of the antenna remains the same. Both the impedance bandwidth and axial ratio bandwidth of the proposed design almost cover the entire UHF band of RFID system and it has the features of easy fabrication and low cost. To verify the proposed design, a prototype is fabricated. Measured results agree well with the simulated results.

DESIGN AND INVESTIGATION OF A DUAL-BAND ANNULAR RING SLOT ANTENNA FOR AIRCRAFT APPLICATIONS

A novel dual-band annular ring slot antenna is investi- gated. The antenna consists of a center-fed circular microstrip patch antenna with a coupled annular ring. And it is shorted concentrically with a set of conductive vias. By adjusting the parameters of the an- tenna, the dual resonant frequencies for two modes (TM01 and TM02 modes) are achieved. The antenna is fabricated and tested. Results show that the proposed antenna with height of 0:0217‚0 can provide gains of 3.01dBi at 2.6GHz (the receiving frequency) and 5.74dBi at 2.95GHz (the transmitting frequency). Good agreement between the measurement and simulation for the return loss and radiation patterns is achieved. The proposed antenna has dual-band characteristics, sim- ple structure, low proflle, and omni-directional azimuth radiation pat- tern. It is suitable for aircraft both receiving and transmitting signals and frequency division duplex (FDD) applications.

Concentric Annular Ring Slot Antenna for Global Navigation Satellite Systems

In this letter, we present the design of a concentric annular ring slot antenna with right-hand circular polarization. Two concentric rings have been etched in the ground plane to generate a dual-band response. A broadband feeding network and a thicker substrate below the slots have been used to improve the axial-ratio bandwidth and gain. The proposed antenna covers the bands of the positioning systems GPS and Galileo. Experimental results show a 3-dB axial-ratio bandwidth for the lower and upper band of 19.2% and 18%, respectively. The measured gain is higher than 4 dB in both bands.

Compact and efficient 2.45 GHz circularly polarised shorted ring-slot rectenna

A compact and efficient rectenna based on a printed shorted annular ring-slot antenna with circular polarisation properties has been designed and evaluated at 2.45 GHz. The rectifier part is localised at the back side and centred inside the radiating element, resulting in a more compact structure in comparison with most conventional devices where rectifying circuit and antenna parts are geometrically clearly separated. In addition, the printed annular ring antenna is mismatched at the 4.9 GHz second and 7.35 GHz third harmonics, thus avoiding the use of an input lowpass filter. The proposed antenna and rectifier circuit have been first simulated and optimised separately using electromagnetic and circuit analyses, and then connected together. A maximum efficiency of 69% and an output DC voltage of 1.1 V have been measured over an optimised 2500 Ω resistive load at a power density of 20 µW/cm2. This rectenna is particularly suitable for powering wireless sensors or sensor networks by recycling ambient RF energy because it exhibits a global efficiency of more than 50% for power densities more than 10 µW/cm2.

A simple design for circularly polarized ring-slot antennas

A simple method for generating circular polarization (CP) radiation from an annular-ring slot antenna is described in this paper.The slot antenna is excited by an L-shaped coupling strip loaded with a resistor. The lengths of the two arms of the coupling strip are the same, and when they are equal to the outer radius of the ring slot, good CP radiation can be directly obtained. Moreover, the resistance value of the loading resistor is insensitive to the axial ratio of the CP antenna. Several prototypes are fabricated, and the measured and simulated results confirm the validity of the propose design. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:2262–2265, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26285