Circularly Polarized Patch Antenna Research Articles

Effective Realization of Higher Order Circular Polarized OAM Mode Circular Patch Antenna

Effective Realization of Higher Order Circular Polarized OAM Mode Circular Patch Antenna

Miniaturized Wideband Circularly Polarized Triangular Patch Antennas based on Characteristic Mode Analysis

A miniaturized, wideband circularly polarized (CP) antenna based on coupled triangular patches is presented. Initially, two identical triangular patches with shorting pins are placed close to each other in a perpendicular orientation. Hence, a pair of orthogonal modes can be produced based on the coupled resonators. Under the characteristic mode analysis (CMA), it can be found that the 90∘ phase difference is achieved by modulating gap distance and shorting pins numbers. Both the shape of triangle patches and shorting pins contribute to the miniaturization. To further improve the AR bandwidth, a third patch is added to form a new mode. Thanks to the triple modes produced by the three patch elements, two AR minima are constructed to broaden the AR bandwidth. With this compact arrangement and shorting pins, a miniaturized wideband CP patch antenna with a 5.2% AR bandwidth is successfully implemented. The overall size of the antenna is merely 0.34λ0×0.33λ0×0.046λ0.

A Circularly-polarized Patch Antenna for BDS Applications

The BDS (Beidou) Navigation Satellite System has been a powerful tool in real-time navigation and positioning. In the transitional stage between BDS-2 and BDS-3, it would be a top priority to ensure the antenna is compatible with the two systems. In our investigations, a circularly-polarized (CP) patch antenna is proposed for receiving B1I signals. This antenna is a newly designed slit-loaded square patch structure. The T-shape structure with F-shape slots is deployed on each edge of the antenna, and a single feed is employed to excite right-hand CP radiation. In simulations, all the parameters of the antenna are optimized through Ansys HFSS. In experiments, the processed antenna is further testified, where the measured bandwidth is compared with the simulated one to verify the effectiveness of the antenna.

A Circularly Polarized Patch Antenna Array with Reduced Mutual Coupling Using the Aperture-Loading Decoupling Technique

An aperture-loaded decoupling strategy for 1 × 8 circularly polarized (CP) patch antenna array is presented in this article. By introducing an additional coupling path, the mutual coupling between adjacent antennas is cancelled. The result shows that more than 20-dB isolation enhancement is obtained by applying this strategy at the center frequency of 3.38 GHz. Mutual coupling between both adjacent and non-adjacent elements are suppressed to less than -25 dB. Moreover, the impedance bandwidth and axial ratio (AR) is also improved with decoupling. Compared with conventional CP antenna decoupling methods, the proposed approach has the characteristics of low profile, compact size, and low impact for the ground plane. It is shown that the AR bandwidth can be enhanced using the proposed decoupling method.

Design and validation of a dual-band circular polarization patch antenna and stripline combiner for the FSSCat mission

The FMPL-2 payload on board the 3Cat-5/A 6 Unit CubeSat, part of the FSSCat CubeSat mission, includes a dual L-Band Microwave Radiometer and a Global Navigation Satellite System Reflectometer, in one instrument, implemented in a Software Defined Radio. One of the design challenges of this payload was its Nadir looking Antenna, which had to be directive (> 12 dB), dual-band at 1400–1427 MHz and 1575.42 MHz, left-hand circularly polarized, and with important envelope restrictions, notably with a low profile. After a trade-off analysis, the best design solution appeared to be an array of six elements each of them being a stacked dual-band patch antenna, with diagonal feed to create the circular polarization, and a six to one stripline combiner. The design process of the elementary antennas first includes a theoretical analysis, to obtain the approximate dimensions. Then, by means of numerical simulations, prototyping, and adjusting the results in the simulations, the manufacturing errors and dielectric constant tolerances, to which patch antennas are very sensitive, can be characterized. A similar approach is taken with the combiner. This article includes the theoretical analysis, simulations, and prototype results, including the Flight Model assembly and characterization.

Estimation of Axial Ratio of Single-Port Dual-Mode Circularly Polarized Antenna Using Reflection Coefficient

In this article, a simple way that can estimate the axial ratio (AR) of a circularly polarized (CP) antenna using its measured reflection coefficient is proposed. The estimation method applies to a single-port CP antenna that is composed of two resonant modes with orthogonal polarization and 90° phase difference. It is most common among CP patch antennas, cross-dipole antennas, and substrate-integrated waveguide antennas. Based on the equivalent circuit model, the analysis method builds a bridge between the reflection coefficient and excitation property. It is shown that the trace property of the reflection coefficient on the Smith Chart infers whether the antenna performs the best AR value and AR bandwidth. By locating impedance points and extracting circuit parameters, accurate circular polarization properties can be estimated. We also provide a numerical way, which is based on an optimization algorithm, to estimate the AR while considering the difference between the two equivalent antenna resonators. A verification program is compiled, and different CP antennas are simulated, fabricated, and analyzed. This study also illustrates the source of estimation errors and proves that the method reaches acceptable AR estimation without time-consuming microwave chamber measurement. Therefore, the method provides a new look to high-speed pre-test and tuning for volume production of CP antennas.

Circularly-Polarized Patch Antennas With Enhanced Bandwidth Based on Capacitively Coupled Orthogonal Patch Radiators

Circularly-Polarized Patch Antennas With Enhanced Bandwidth Based on Capacitively Coupled Orthogonal Patch Radiators

Hexagonal-Triangular Combinatorial Structure Based Dual-Band Circularly Polarized Patch Antenna for GAGAN Receivers

A multilayer gap-coupled dual band hexagonal microstrip patch antenna is presented for GPS Aided GEO Augmented Navigation (GAGAN) receivers. GAGAN is developed by AAI (Airport Authority of India) and ISRO (Indian Space Research Organization) exclusively for aviation purposes with the GPS frequencies L5 (1176.45 MHz) and L1 (1575.42 MHz). The proposed GAGAN antenna has three trapezoidal and four equilateral triangular patch resonators configured to form a gap-coupled hexagonal patch on the top layer and seven equilateral triangular patches with slots in between to form the middle layer. Both the layers are fed by a single coax feed to achieve a dual band compact microstrip antenna of size 55 mm x 55 mm x 3.2 mm. Instead of designing the hexagonal antenna conventionally from a circular patch antenna, the sides of the equilateral triangular patch are truncated to obtain the proposed compact hexagonal antenna as the triangular antenna occupies less area when compared to circular or square patches for a fixed frequency. To bring in novelty with improved performance, the combinatorial structured configuration has been explored through step-by-step optimization. The aspects of GAGAN requirements like circular polarization with a single input, dual band operation and high gain with gain flatness are achieved with this compact structured antenna when compared to square and circular patch antennas. The combinatorial structures such as perturbation and truncation introduced in the patches are responsible for exciting two near-degenerate orthogonal modes producing circular polarization (CP). A cross slot etched in the center patch results in gain enhancement with a gain above 3.2 dBi over a bandwidth of 20 MHz in both the bands. Five shorting pins are added to achieve high impedance matching and good CP with an axial ratio (AR) below 2 dB. The simulated and measured results are found to be in good agreement with greater than 20 MHz operational bandwidth exhibiting CP with an omni-directional radiation pattern having high cross polar levels of -22 dB. The size reduction achieved in the proposed design is 56.79% when compared to the conventional hexagonal patch antenna. The measured 10 dB impedance bandwidth is 2.7% and 2.1% for L5 and L1 bands respectively with a 3 dB AR bandwidth of 2.3% for L5 and 2.0% for L1, satisfying GAGAN requirements.

A Compact Broadband Circularly Polarized Patch Antenna Using Ladder Slots and Grounded Capacitors for MedRadio-Band Applications

A Compact Broadband Circularly Polarized Patch Antenna Using Ladder Slots and Grounded Capacitors for MedRadio-Band Applications

A compact mesoband microwave radiation system.

A compact mesoband radiation system is designed and tested. The system is composed of a charging power supply, a Marx generator, a switched quarter-wavelength oscillator, and a circularly polarized patch antenna. The Marx generator outputs a fast high-voltage pulse with a rise time of 10ns and an amplitude of 100kV, which is used to charge the oscillator. The oscillator consists of a quarter-wavelength coaxial transmission line, a ring ground switch, and a coupler. It generates a mesoband oscillation pulse with a center frequency of 350MHz and a percentage bandwidth of 10%. The oscillation pulse is radiated by the circularly polarized patch antenna. The measured radiation factor is greater than 50kV, and the radiation waveform is consistent with the simulation waveform.

A novel circularly polarized patch antenna based on polarization conversion metasurface for radiation and scattering performance improvement

A new design based on sequential-rotation arranged polarization conversion metasurfaces (PCMs) is proposed for reducing backscattering and improving radiation performance of circularly polarized (CP) patch antennas. The proposed antenna is composed of a conventional corner-truncated patch antenna loaded with a PCMs. The configuration of the PCMs increases the operating bandwidth and realized gain, as well as reduce radar cross section (RCS). The relative CP bandwidth (both |S11| < −10 dB and AR <3 dB) is improved to 13.65% due to achieving an additional mode by the PCMs. Also, the peak gain is enhanced by 6.6 dB. Moreover, an in-band and out-of-band RCS reduction is achieved compared with the conventional CP patch antenna due to the polarization conversion characteristic of the PCMs. The maximum RCS reduction is 27.5 dB within the band. This design enables an effective strategy for wideband, high-gain, and low-RCS CP patch antennas. A sample operating at C-band was fabricated and measured, demonstrating a satisfactory match between simulation and measurement results, so verifying the proposed idea.

Axial ratio bandwidth enhanced circularly polarized transmitarray antenna with a flat gain response.

In this paper, a novel broadband circularly polarized transmitarray antenna (CPTA) enabled by axial-ratio-improved receiver-transmitter metasurface loaded with parasitic patches is proposed. Split-ring-shaped parasitic patch is utilized to generate an additional resonant mode and significantly broaden the 3-dB axial ratio (AR) bandwidth of proposed receiver/transmitter patches from 6.64% to 15.61%. By cascading the receiver and transmitter with the same polarization and then rotating the cell, Pancharatnam-Berry phase can be exploited for providing a 2π phase shift. As verification, a CPTA prototype integrated with a self-made circularly polarized patch antenna is designed, fabricated, and measured. Experimental results show that the proposed CPTA obtains a 3-dB AR bandwidth of 27.1% from 12.1 to 15.9 GHz and an impedance bandwidth of 20.6% from 12.5 to 15.2 GHz. Additionally, it has a flat gain with a 3-dB gain bandwidth of 18.8% from 12.5 to 15.1 GHz, and a maximum gain of 25.6 dBi at 13.1 GHz is achieved. With the advantages of simple design, wide AR bandwidth, and flat gain performance, the proposed CPTA presents great potential applications in wireless systems.

Broadband metasurface superstrate for polarization-independent wave focusing and gain enhancement at Ka-band

A broadband metasurface flat lens is proposed as a polarization-independent wideband superstrate for wave focusing and gain enhancement at Ka-band. The proposed metasurface structure consists of four metal layers and is designed with diagonally symmetric unit cells to accommodate both the vertical and horizontal polarizations. The focusing ability of the proposed metasurface flat lens is validated via simulation and measurement, where normally incident plane waves are shown to be enhanced by up to 11 dB as a result of wave focusing. Also, the radiation gain enhancement due to the proposed metasurface flat lens is demonstrated via simulation and measurement, where a gain enhancement of up to 10.5 dB is achieved. The results show that the proposed structure maintains the wave focusing and gain enhancement characteristics over a bandwidth of 28–32 GHz. Furthermore, to demonstrate the utility of the proposed metasurface for circular polarization (CP), the gain enhancement of a CP patch antenna as a result of implementing the proposed metasurface as a superstrate is demonstrated via simulation and measurement. It is shown that the proposed metasurface superstrate provides a CP gain enhancement of nearly 10 dB.

Compact Wideband Circularly Polarized Patch Antenna Array Using Self-Sequential Rotation Technology

In this letter, a compact wideband circularly polarized patch antenna array is proposed to cover the 57&#x2013;71 GHz band. The antenna array is constructed by 45<inline-formula><tex-math notation="LaTeX">$^\circ$</tex-math></inline-formula> inclined slits loaded circular radiating patches with rectangular back cavities, two-layer sequential rotation feed networks, and a waveguide transition. Novel self-sequential rotation technology is introduced using a dual-high-order-mode cavity to improve the axial ratio (AR) and impedance bandwidths of the subarray. Compared with conventional sequential rotation feed networks, the proposed feeding scheme provides higher aperture efficiency. A 4 &#x00D7; 4 patch antenna array is fabricated using standard printed circuit board technology. Measured results show that the <inline-formula><tex-math notation="LaTeX">$-$</tex-math></inline-formula>10 dB impedance and 3 dB AR overlapped bandwidth is 23.8&#x0025;(57&#x2013;72.3 GHz). The measured peak gain is 20.5 dBic with an aperture efficiency of 87.7&#x0025; at 66 GHz.

Harmonic Suppression and Size Reduction of a Low-Profile CP Patch Antenna by Using Nondegenerate Modes

A novel design method of harmonic suppression and size reduction of a circularly polarized (CP) microstrip patch antenna (MPA) is presented by using nondegenerate modes. Based on a circular MPA, a pair of orthogonal modes could be generated between these undesired resonant modes. Then, by loading the shorting pins in a quarter fan-shaped patch, all these undesirable high-order modes could be suppressed between them. After that, the higher and lower modes are moved closer to each other by cutting a long slot at the angle bisector of the fan-shaped patch, providing the CP radiation pattern. Finally, a prototype of this proposed antenna has been designed, produced, and measured to verify the design concept. The experimental results show that the proposed antenna has an impedance bandwidth of 286 MHz (13 774–14 060 MHz), axial ratio bandwidth of 80 MHz (13 900–13 980 MHz), and a left-hand CP peak gain of around 4.8 dBi. Most importantly, the CP antenna has realized the harmonic suppression of about 15 GHz, which has an obvious advantage as compared to the traditional CP MPA. Moreover, the antenna still holds the primary low-profile, single-radiator, simple structure, and high-efficiency simultaneously.

Flexible and Transparent Circularly Polarized Patch Antenna for Reliable Unobtrusive Wearable Wireless Communications

This paper presents a circularly polarized flexible and transparent circular patch antenna suitable for body-worn wireless-communications. Circular polarization is highly beneficial in wearable wireless communications, where antennas, as a key component of the RF front-end, operate in dynamic environments, such as the human body. The demonstrated antenna is realized with highly flexible, robust and transparent conductive-fabric-polymer composite. The performance of the explored flexible-transparent antenna is also compared with its non-transparent counterpart manufactured with non-transparent conductive fabric. This comparison further demonstrates the suitability of the proposed materials for the target unobtrusive wearable applications. Detailed numerical and experimental investigations are explored in this paper to verify the proposed design. Moreover, the compatibility of the antenna in wearable applications is evaluated by testing the performance on a forearm phantom and calculating the specific absorption rate (SAR).

A Metasurface-Based Wide-Bandwidth and High-Gain Circularly Polarized Patch Antenna

A metasurface-based circularly polarized (CP) microstrip patch antenna with high performance in terms of the global bandwidth and gain is presented. The antenna configuration was a square-modified microstrip patch that was sandwiched between a metasurface and the ground plane. The metasurface comprised a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$4 \times 4$ </tex-math></inline-formula> array of square patches, while the single-feed radiating microstrip patch had axial ratio (AR) tuning stubs and a crossed slot. Under excitation, the microstrip patch and crossed slot, in conjunction with the metasurface, generated multiple resonances and AR minimum points that combined to produce large global bandwidths with regard to the impedance, AR, and 3 dB gain. Using a stacked layout, a low-profile design with the dimensions of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$54\,\,\text {mm} \times 54\,\,\text {mm} \times 3.1$ </tex-math></inline-formula> mm ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1.2\,\,\lambda _{\text {o}} \times 1.2\,\,\lambda _{\text {o}}\times 0.07\,\,\lambda _{\text {o}}$ </tex-math></inline-formula> at 6.8 GHz) was obtained, which generated a highly stable broadside gain above 10 dBic throughout the entire operating AR bandwidth. This antenna had a measured −10 dB impedance bandwidth of 5.62–11.04 GHz (65.06%) and a 3 dB AR bandwidth of 5.64–7.89 GHz (33.25%). In addition, it had a measured 3 dB gain bandwidth of 5.17–8.2 GHz (45.32%), with a measured peak gain of 12.17 dBic.

Detection of Kidney Cancer Using Circularly Polarized Patch Antenna Array

The use of a circularly polarized patch antenna array to detect kidney cancer by microwave techniques is proposed in this paper. A four-element linear antenna array is designed and fabricated at the ISM frequency of 2.4 GHz. The dimensions of the antenna array are 200 mm &#x00D7; 78 mm. The single element is a square patch with side length of 30 mm. The distance between patches is chosen to be 20 mm which ensures that mutual coupling between any two adjacent patches is less than 20 dBs. The substrate is a FR-4 material of relative permittivity 4.3 and thickness 1.6 mm. The circular polarization has an axial ratio of 0.8 dB at 2.4 GHz. The bandwidth at S₁₁ = -10 dB is 7.23 %. Renal system phantom consisting of kidney cortex, renal capsule, ureter, adrenal gland, muscle, fat, and skin is used. Four stages of renal cancer tumors are considered depending upon the tumor size in each stage. The presence of a tumor causes an increase in the reflection coefficient (S₁₁) and a shift in resonance frequency, which can be used to identify cancer. The increase in reflection coefficient and the shift in resonance frequency are calculated for each stage of the cancer tumors. The shift in resonance frequency for the early stages is too small. Therefore, detection depends mainly on the increase in S₁₁. The shift in resonance frequency and increase in S₁₁ are large for advanced stages of the tumor, which makes detection easier. Computed specific absorption rate (SAR) is found to be less than the safety levels, which means this technique is safe to use. Overall, this work suggests a new simple detection technique of kidney cancer. The advantages of this technique are safety, compact, fast, inexpensive, comfortable examination, non-invasive, and finally non- ionizing radiation during measurement.

Dual circularly polarized Fabry-Perot antenna with metamaterial-based corner reflector for high gain and high aperture efficiency

Based on the ray-tracing model, a new method of achieving a high gain and high aperture efficiency Fabry-Perot antenna with metamaterial-based corner reflector is proposed. The proposed Fabry-Perot antenna is composed of a dual circularly polarized patch antenna feed and the metamaterial-based corner reflector. The metamaterial-based corner reflector consists of four phase correction metasurfaces and a partially reflective surface. First, theory and analysis of the Fabry-Perot antenna with metamaterial-based corner reflector are presented. Then, the performances of the dual circularly polarized antenna feed, the traditional Fabry-Perot antenna, and the Fabry-Perot antenna with metamaterial-based corner reflector are compared among each other and analyzed. Finally, the proposed Fabry-Perot antenna is fabricated and measured. The measured left-hand circular polarization (LHCP) gain and the measured right-hand circular polarization (RHCP) gain of the proposed Fabry-Perot antenna are 21.4 dBi and 21.3 dBi, respectively. Comparing with the antenna feed, the LHCP gain and RHCP gain of the proposed Fabry-Perot antenna are enhanced by 16.4 dB and 16.3 dB, respectively. Compared with the traditional Fabry-Perot antenna, the metamaterial-based corner reflector acts as both a reflection surface and a phase correction surface. It manipulates the propagation direction and phase of electromagnetic wave. The proposed Fabry-Perot antenna with high gain, high aperture efficiency and low sidelobe at 2.8 GHz paves the way for developing the solar radio telescope and conducting the observation.

A Low-profile and Low-cost Dual Circularly Polarized Patch Antenna

A Low-profile and Low-cost Dual Circularly Polarized Patch Antenna