Dual-band Circular Polarization Research Articles

A superstrate loaded aperture coupled dual-band circularly polarized dielectric resonator antenna for X-band communications

AbstractA superstrate loaded cylindrical dielectric resonator antenna is developed and demonstrated for dual-band circular polarization. The proposed antenna employs a microstrip-fed rotated cross-shaped slot coupling technique for exciting the dielectric resonator (DR). The design is developed in a straight forward way. Firstly, the DR is coupled with a conventional plus-shaped slot and operates in linear polarization mode at 7.4 and 11.2 GHz. Secondly, the slot is rotated by 10° to enable out-of-phase excitation and ensure circular polarization at the above-mentioned frequencies. In the third step, a square dielectric superstrate is placed above the DR which creates multiple reflection and enhance the gain up to ~8 dBi in both the frequencies without affecting other performances. The development stages are discussed in detail. The proposed design is demonstrated through prototype fabrication and characterization. This antenna can be used for X-band satellite communications.

Two-port dual-band circularly polarized dielectric resonator-based MIMO antenna with polarization diversity

ABSTRACT In this communication, dielectric resonator based two-port Multi Input Multi Output (MIMO) antenna is structured and examined. L-shaped microstrip line with a serial step impedance transformer is used to excite moon-shaped aperture, which in turn stimulates ring-shaped dielectric resonator antenna. Some of the important features of the proposed MIMO radiator are: (i) alteration of cylindrical to ring-shaped dielectric resonator is supportive to give wide-impedance bandwidth; (ii) aperture excites dual orthogonal hybrid ( and ) mode inside the ring dielectric resonator antenna, which aids to get dual-band circular polarization waves; and (iii) use of polarization diversity concept is helpful to give lesser mutual coupling (less than −20 dB) between the ports. After doing experimental confirmation, the proposed radiator is working over the frequency range 2.4–3.88 GHz. It also supports 3-dB axial ratio in dual-frequency range, i.e., 2.44–2.64 GHz and 3.4–3.65 GHz, respectively. Right-handed circular polarization and good value of diversity parameters make the proposed antenna employable for WLAN (2.5 GHz) and WiMAX (3.3 GHz) applications.

Tunable circularly polarized graphene antenna for THz applications

A technique is implemented for the generation of tunable circularly polarized THz wave using patterned graphene patch. The aspect ratio of graphene patch is selected to operate with the harmonics at frequency 1.7, 2.23, 3.26 and 3.41 THz covering three bands 1.67 - 1.73, 2.18 - 2.27 and 3.17 - 3.49 THz. The graphene patch is perturbed by inserting a patterned slot to generate the set of orthogonal magnetic dipoles and hence the CP wave. Insertion of slot shifts the resonant frequency of the generated harmonics at 2.95, 3.59, 4.89 and 5.068 THz covering the bands 2.86 - 2.99, 3.54 - 3.66 and 4.83 - 5.12 THz. Also, the dual-band circular polarization is obtained with 3-dB axial ratio bandwidth of 1.68 % (2.94 - 2.99 THz) and 0.4 % (4.99 - 5.01 THz) in the first and third operating band, respectively. Furthermore, the utilization of graphene in the radiator provides the frequency tunability of generated CP wave by varying the chemical potential. The antenna can be utilized in the biomedical applications at THz frequency band.

Dual-Sense Circularly Polarized Antenna With a Dual-Coupled Line

This letter presents a dual-sense circularly polarized (CP) microstrip patch antenna with a dual-coupled line. The rectangular patch antenna operating in TM01 mode is utilized as a basic design, and a single-coupled line is introduced to excite the TM10 mode with a phase difference of 90°, generating CP operation. As different polarizations can be obtained by changing the position of the single-coupled line, a dual-coupled line is introduced to the rectangular patch antenna to excite two CP modes with different polarizations. The prototype of the dual-band dual-sense CP antenna is fabricated and measured. The measured results illustrate that the dual-sense CP antenna obtains a wide impedance bandwidth of 7.95% and dual axial ratio (AR) bandwidth of 0.33% for the left-hand circular polarization (LHCP) and 0.72% for the right-hand circular polarization (RHCP). Furthermore, the antenna has a wide 3 dB axial-ratio beamwidth and a small frequency ratio of 1.04.

Dual-Band Circularly Polarized Transmitarray With Single Linearly Polarized Feed

This communication proposes a novel method to design a dual-band circularly polarized (CP) transmitarray (TA) antenna with a linearly polarized (LP) feed. By using this method, a shared-aperture dual-band TA is developed, which forms independent beams with right-hand circular polarization (RHCP) or left-hand circular polarization (LHCP) in two frequency bands with a single LP feed antenna. Four different CP TA prototypes operating at 12 and 14.2 GHz with different senses of CP and different beam directions are designed, and two of the prototypes are fabricated to validate the design concepts. A good agreement is obtained between the radiation patterns, gain curves, polarizations, and cross polarization levels measured and computed in both frequency bands. The proposed single-source dual-band CP TA design has advantages of simple structure, lightweight, easy fabrication, low cost, and high performance, making it a good candidate for varied applications.

A Jia-shaped artistic patch antenna for dual-band circular polarization

This article presents a novel single-feed circularly polarized patch antenna for dual-band (2.6 and 3.4 GHz) applications. Details of the design procedure and design considerations of the proposed antenna are described. The novelties of the proposed antenna are counted by (i) a meaningful Jia-shaped patch used as the primary radiator; (ii) a 3D L-shaped feeding probe used to excite the stacked patches so that the near degenerate-modes are excited at the desired dual band; (iii) down-tilt beams achieved that are particularly suitable for wall-mount base-stations. The measured 3-dB axial-ratio bandwidths are 2.41–2.61 GHz and 3.25–3.42 GHz, where the maximum gains are recorded as 7.3 and 6.3 dBic, respectively. Methods for the adjustment of band ratio down to 1.18 are discussed. The overall antenna size is 100 × 100 × 12.8 mm3.

Dual Wide Band Circularly Polarized Microstrip Patch Antenna with Offset Feed

Dual Wide Band Circularly Polarized Microstrip Patch Antenna with Offset Feed

A Dual-Band Circularly Polarized Antenna With a Dual-Band AMC Reflector for RFID Readers

This letter proposes a circular patch antenna with dual-band circular polarization at the UHF-RFID and WLAN bands. Two perpendicular slots are etched on the patch to down-shift the first resonance to 915 MHz (UHF-RFID band) and introduce a new resonance at 2.45 GHz (WLAN band). Four slits are etched on the ground plane to improve axial ratio (AR) mainly in the first band. A dual-band AMC reflector having 25 unit cells is placed a small distance below the patch to reduce the backlobe level and improve the gain at both bands. Measured 3 dB AR bandwidths of 5.25% and 2% are achieved at UHF-RFID and WLAN bands respectively with gains of 3.1 dBi (UHF-RFID) and 6.25 dBi (WLAN). The antenna system can be used with RFID readers for detecting tags and sending information via the WLAN band.

Reconfigurable Dual-/Triple-Band Circularly Polarized Dielectric Resonator Antenna

In this letter, a probe-fed reconfigurable dual-/triple-band circularly polarized (CP) Spidron fractal dielectric resonator antenna (SFDRA) is proposed. Initially, a dual-band CP SFDRA is designed. An eigen-mode simulation of an isolated SFDR concludes that the quasi-TM $_{11\delta }$ and quasi-TM $_{21\delta }$ are excited in the lower band, whereas the quasi-TE $_{12\delta }$ mode is excited in the upper CP band. The modes of the lower CP band are separated by etching a T-shaped slot from the ground plane, thereby achieving overall triple-band circular polarization. In addition, the TSS being $\lambda _g/2$ in length at 2.64 GHz produces a band-notch function. CP band reconfigurability is attained by placing a diode D1 across the width of the TSS such that the on -/ off -state of the D1 radiates dual-/triple-band CP waves. The measurement results in the on -[ off ]-state show the impedance bandwidths for $\mathopen |$ $S_{11}\mathclose | $-$ 10 dB of 57.60% (2.2–3.98 GHz) [14.44% (2.12–2.45) and 40.48% (2.64–3.98 GHz)] and the 3 dB axial-ratio bandwidths of 24% (2.31–2.94 GHz) and 6.82% (3.68–3.94 GHz) [6.34% (2.29–2.44 GHz), 6.65% (2.76–2.95) and 7.09% (3.67–3.94 GHz)] in an ascending order of the frequency. A reasonable match is observed between the simulated and experimental data.

Dual-Band Circularly Polarized Dielectric Resonator Antenna for WLAN and WiMAX Applications.

In this paper, a new dual-band circularly polarized (CP) dielectric resonator antenna for WLAN and WiMAX applications is proposed. The dielectric resonator has an asymmetric Y-shaped geometry. By properly selecting the length of the arms, the pairs of fundamental (TE) and second-order (TE) are excited separately at the design frequencies to radiate the CP wave. The measurement shows that the fabricated antenna exhibits a wide impedance bandwidth for |S−10 dB of 62.07% (2.2–4.18 GHz). The far-field measurements in the broadside direction demonstrated a dual-band CP response with 3 dB ARBWs of 4.92%(2.38–2.5 GHz) at the lower and 12.64% (3.26–3.70 GHz) at the upper band. The measured CP bands cover the entire frequency range of WLAN (2.401–2.495 GHz) and WiMAX (3.4–3.69 GHz) at the lower and upper bands, respectively.

A Reconfigurable Printed Antenna With Frequency and Polarization Diversity Based on Bow-Tie Dipole Structure

In this communication, a novel frequency and polarization-reconfigurable antenna is designed based on simple dipole-type structure. It is composed by two symmetric bow-tie arms and four switching circuits. Four p-i-n diode switches are used to change the connection state of the bow-tie arms and other four patches. By switching the states of four p-i-n diodes, both the amplitude and phase of the surface currents at different frequencies can be controlled. It follows that an adjustable antenna in frequency and polarization can be devised. As a result, this antenna can realize different working modes. It can be mainly classified into six modes: two single broadband frequency linear polarization (LP) modes (Modes 1 and 2), two dual-broadband LP modes (Modes 3 and 4), and two dual-band circular polarization (CP) modes (Modes 5 and 6). In order to verify the accuracy of this design, this antenna is designed, fabricated, and tested. The measurement results agree very well with the simulation results.

Dual-Band Dual Circularly Polarized Antenna Array Using FSS-Integrated Polarization Rotation AMC Ground for Vehicle Satellite Communications

This paper presents a new dual-band dual circularly polarized (CP) high gain patch antenna array for vehicle satellite communications. The array consists of 16 linearly polarized dual-band elements backed with a new frequency-selective-surface (FSS)-integrated polarization rotation ground. The polarization rotation ground is located underneath the array, which not only acts as a reflector to increase the array boresight gain but also enables the array's dual CP radiation. The electromagnetic (EM) waves reflected by the ground retard either 90° or 270° with respect to the EM waves of the array directly radiated to the upper sphere at two frequency bands, leading to the dual-band dual CP radiation. This is totally different from many of the former counterparts which are based on either the perturbation on the stacked patch or external feeding network. Measured results show the −10-dB impedance bandwidth is from 7.8 to more than 8.5-GHz for X-band and from 14 to 15.3-GHz for Ku-band. The 3-dB axial ratio bandwidth is from 8.15 to 8.35-GHz for the lower band (right-hand CP) and from 14.2 to 14.8-GHz for the higher band (left-hand CP), respectively.

Dual-layer and dual-polarized metamaterial inspired antenna using circular-complementary split ring resonator mushroom and metasurface for wireless applications

A compact triple-band and dual-polarized metamaterial inspired antenna loaded with a reactive impedance surface (RIS) based metasurface is presented in this work. The dual-band circular polarization (CP) characteristics are obtained by the combination of the conventional slotted patch loaded with circular-complementary split-ring resonator based mushroom stacked with RIS. The CP radiation is generated due to the introduction of asymmetry in the antenna structure results in the splitting of fundamental mode into two orthogonally polarized modes with 90° phase difference at the resonating frequency. The antenna obtains an overall electrical size of 0.27λ0 × 0.27 λ0 × 0.027λ0 with radiating element size of 0.16λ0 × 0.16 λ0 at 1.7 GHz with ka = 0.72. The final antenna prototype is fabricated and measured which covers bandwidths of (1.66–1.72 GHz) 3.52%, (1.94–2.20 GHz) 13% and (3.68–3.87 GHz) 5.02% for the three bands. The antenna exhibits CP radiation at 2.10 GHz and 3.78 GHz with an axial ratio bandwidth (ARBW) of 2.85% and 1.85% are obtained for the two bands, respectively. Due to the loading of RIS, the antenna gain enhanced to 1.6 dBi, 4.74 dBic, and 3.28 dBic at the three respective frequencies with an overall area reduction of 52.32% is achieved. The antenna provides a wider AR beamwidth for CP radiation (ARBW < 3) with positive gain values for theta = ±58° and for all phi values at 2.1 GHz. Hence, the proposed antenna can be used for working in 1.7 GHz LTE (1.66–1.72 GHz), 2.2 GHz UMTS (1.94–2.20 GHz), 3.8 GHz WiMAX (3.68–3.87 GHz), and small satellite application systems at 2.1 GHz applications.

Metamaterial-Loaded Compact High-Gain Dual-Band Circularly Polarized Implantable Antenna System for Multiple Biomedical Applications

This communication presents a metamaterial (MTM)-loaded compact dual-band circularly polarized antenna system suitable for multiple bio-telemetric applications. The proposed antenna system operates in the industrial, scientific, and medical (ISM) bands with center frequencies: 915 MHz (902–928 MHz) and 2450 MHz (2400–2480 MHz). The integration of an MTM structure with epsilon-very-large property on the superstrate layer of the antenna produces significant gain enhancement and strong circular polarization (CP) behavior at both the operating frequencies. The key features of the proposed antenna system are its compact size (7 mm $\times 6$ mm $\times $ 0.254 mm), dual-band CP characteristics, significantly high gain values (−17.1 and −9.81 dBi in the lower and upper bands, respectively), and slot-less ground plane that reduces the complexity and backscatter radiation. The performance of the MTM-loaded antenna system is validated experimentally. The antenna is fabricated and integrated with dummy electronics and batteries and is enclosed in a 3-D printed device. The hermetically sealed device is tested in minced pork muscle to validate the simulation results. The measured impedance bandwidths of 35.8% and 17.8% are obtained in the lower and upper ISM bands, respectively. The specific absorption rate of the antenna system is evaluated at both frequencies in different tissues. Additionally, to determine the wireless communication range, the link margin is estimated at data rates of 100 kbps and 1 Mbps.

Polarization Reconfigurable Dual-Band Rectangular Slot Antenna

Abstract A novel dual-band rectangular slot antenna is presented for dual-sense reconfigurable polarization. A W-shaped microstrip feedline and two rectangular parasitic patches are used to obtain dual-band circular polarization. Further, the feedline is modified so that the senses of polarization at the two bands are opposite. By introducing PIN-diodes in the feed lines, polarization can be switched among left-hand circular polarization (LHCP), right-hand circular polarization (RHCP), and linear polarization (LP). A prototype dual-band dual-sense antenna with f01 = 1.9 GHz and f02 = 3.45 GHz is fabricated in a 1.6 mm thick FR4 substrate. The measured circular polarized bandwidths are more than 7.6 % for the lower band and 5 % for the upper band.

Polarisation reconfigurable dual‐band circularly polarised patch antenna with defected ground plane for C‐band wireless applications

Here, a novel geometry of dual-band polarisation reconfigurable patch antenna is presented. The proposed prototype design consists of two orthogonal arms as a patch, an inclined slotted asymmetric pentagonal-shaped ground plane and a PIN diode with a biasing circuit. The polarisation reconfiguration is controlled via ON/OFF states of the PIN diode. The unique feature of the proposed antenna design is that it provides polarisation reconfiguration without considerable deviation in −10 dB impedance bandwidth (IBW) frequency response. The proposed antenna has a measured −10 dB IBW of 49.28% (3.96–6.55 GHz) and 41.47% (4.3–6.55 GHz) in the ON-state and OFF-states of the PIN diode, respectively. In the ON-state of the PIN diode, the antenna exhibits a dual-band circular polarisation. The first 3 dB axial ratio (AR) band is 4.5% (4.3–4.5 GHz) and the second 3 dB AR band is 17.69% (5.1–6.09 GHz). The proposed antenna exhibits almost uniform gain over the entire operating axial-ratio bandwidth, with peak CP gain of 2.8 dBic. The suggested antenna has a wide −10 dB IBW, and it is suitable for C-band wireless applications.

Dual‐band metasurface‐based CP low‐profile patch antenna with parasitic elements

A single-feed dual-band circularly polarised (CP) patch antenna is proposed. The antenna consists of a corner-truncated square patch antenna and a superstrate composed of a lattice of 2 × 2 metallic patches surrounded by parasitic elements. The driven patch generates one resonant mode. The metasurface with parasitic elements excites two additional resonant modes (TM10 and TM20). The combined resonances result in minimum axial ratio points, and a good dual-band CP operation is achieved. Simulations show that the antenna has a CP operating bandwidth of 40 MHz centred at 3.72 GHz (1.07%), and a CP operating bandwidth from 5.37 to 6.05 GHz (11.9%). The simulated gain is ∼7.05–7.1 dBic for the low-frequency band and 4.17–6.07 dBic for the high-frequency band, respectively. Measurements and simulations are in good agreement.

Dual-Band Circular Polarized Flexible Implantable Antenna Using Reactive Impedance Substrate

This communication presents a compact wideband implantable loop antenna with circular polarization (CP) characteristics at 920 MHz industrial scientific and medical (ISM) (902–928 MHz) band and 2.45 GHz ISM band (2.40–2.48 GHz). To widen the impedance bandwidth (IBW) and improve the axial ratio (AR) behavior of the antenna, a reactive impedance substrate (RIS) is exploited. Meandering each arm of the loop makes the antenna compact in size, while the generation of surface wave by the RIS and open-ended configuration of the antenna collectively renders circular polarized wave. The performance of the antenna is analyzed using a single-layer skin model and other existing phantom models. The key feature of the proposed antenna is its dual-band CP behavior, which persists even at the flexion deformation of the human skin. An IBW of 123% with a 3 dB AR bandwidth of 15% and 8.7% is obtained at the planar state of the skin implantable antenna. To validate the simulated results, in vitro measurements were experimentally performed. Also, to find the maximum transmission range of the antenna for biotelemetry communication, the link margin has been analyzed. Finally, to use the antenna inside the biomedical device, the effect of microelectronic components is investigated.

Dual‐band circular polarisation generation technique with the miniaturisation of a rectangular dielectric resonator antenna

A technique is proposed to obtain the dual-band circularly polarised (CP) response along with the miniaturisation of a singly fed rectangular dielectric resonator (DR) antenna. The miniaturised response is obtained by applying the metallic strips on the sidewalls of the DR. The specific format of the applied metallic strips excites the orthogonal degenerate modes. Thus, a dual-band CP response is obtained along with the miniaturisation of antenna. The proposed antenna is designed to obtain the small frequency ratio. The frequency ratio can also be tuned by changing the surface area of the applied metallic strips.

Dual-band and high-efficiency circular polarization conversion via asymmetric transmission with anisotropic metamaterial in the terahertz region

In this paper, we present an anisotropic metamaterial (AMM) composed of a sub-wavelength metal grating sandwiched with bi-layered double-arrow-shaped (DAS) structure array, which can achieve high-efficiency circular polarization (CP) conversion via giant asymmetric transmission (AT) in terahertz (THz) region. Numerical simulation results indicate that near complete CP conversion with cross-polarization transmission coefficients can reach 0.91 and 0.93, which can be observed at 0.31 and 0.55 THz, respectively. Based on the combination of polarization conversion effects and Fabry-Perot-like cavity-enhanced effect of AMMs, the AT parameter for CP wave can reach a maximum of 0.83 at 0.30 THz, and 0.87 at 0.56 THz, respectively. With appropriate geometric parameters design of each unit-cell, embedded in the proposed AMM, the cross-polarization transmission coefficient and AT parameter for CP waves can be increased to the maximal values of 0.98 and 0.9, respectively. The proposed AMM shows great potential applications in high performance dual-band CP convertor and isolator in THz region.