Novel Circularly Polarized Square Microstrip Antenna with L-Slits

This paper discussed the design of a simple square microstrip patch that had a circular polarization type. One application that requires a circular polarization type is global positioning system (GPS) with a working frequency of 1575 MHz. The technique used to produce circular polarization is by shifting the feed line position and truncated corner of the patch. The optimal design was obtained by analyzing the changed of feed line position and truncated corner size of the patch. The initial design was performed theoretically, then simulated using the AWR simulator and measured experimentally. Measurement results using a vector network analyzer show that the antenna design achieves the return loss of −26.04 dB and VSWR of 1.1 at frequency of 1575 MHz. The axial ratio below 3 dB was obtained for the range 1540 – 1580 MHz.

A novel design of small slot-coupled circularly-polarised circular microstrip antenna with a modified cross-slot cut in the patch and a bent tuning-stub aligned along the patch boundary is proposed and experimentally studied. Results show that, for fixed circular polarisation (CP) operation, the antenna proposed can have an antenna size reduction of /spl sim/80%, as compared to a regular-size CP design. The significant size reduction of the proposed antenna is due to the novel modified cross-slot cut in the patch, and CP operation is obtained using a bent tuning-stub incorporating a properly oriented coupling-slot in the ground plane of the microstrip feed line.

With the introduction of the circularly symmetrical slot near the coaxial feed location of the corner truncated square microstrip antenna patch, both the circular polarization and harmonic suppression performance can be realized in this antenna. Effectiveness of the circularly symmetrical slot for harmonic suppression is studied, including its affection to circular polarization performance of the antenna. Experimental results show that application of the circularly symmetrical slot near the coaxial feed location of the microstrip antenna patch can remarkably suppress the harmonic frequencies. Measured radiation patterns indicate that the forward radiation is suppressed by more than 10~20 dB at the second and the third harmonic frequencies compared to the reference antenna, while maintaining the circular polarization performance, the cross polarization, and the backward radiation.

A new configuration for a circularly polarised microstrip antenna with an omnidirectional pattern is proposed. This antenna consists of two rectangular patches with perturbation segments, which are arranged back-to-back relative to a coplanar waveguide (CPW) on a ground plane. The characteristics of the proposed antenna were clarified by experiments, and the mechanism to produce the circular polarisation was proved by using an electromagnetic simulator. The radiation patterns and input impedances were measured as a parameter of the width of the perturbation segment. Good circularly polarised radiation patterns with an omnidirectional pattern and input impedance characteristics were obtained.

This paper proposes new design of square microstrip antenna with dual feed line for improving bandwidth and axial ratio at work frequency of 2400 MHz. To obtained circular polarization with axial ratio ≤ 3 dB and enhanced bandwidth of antenna, dual feed line is used to improve performance of conventional microstrip antenna. After the simulation process, dual feed line succeed to improved bandwidth of microstrip antenna 131.9 % compared with microstrip antenna with single feed and provide circular polarization with axial ratio 2.44 dB at working frequency of 2400 MHz. compared to the microstrip antenna with a single feed. This research is very usefull for Wi-Fi application in order to improve the level quality of receiver signal.

This paper presents a new design for a Circularly Polarized Square Slot Antenna (CPSSA). The proposed antenna is single layered with L-shaped stubs loaded on both the opposite corners of the antenna, which is capable of generating orthogonal modes for the excitation of Circular Polarization. Two asymmetric strips on the top and the left portions of the proposed antenna and various other asymmetric strips are also loaded. The proposed structure is having the dimensions of 40 x 40 x 1.6 mm3.The designed CPSSA operates in the range of 3.2-12.5 GHz with Axial Ratio (AR) bandwidth in the range of 4.5-8.5 GHz. In this paper the improvement of the performance parameters like AR and Return Loss (S 11 ) on the addition of asymmetric stubs is explained in detail.

This paper presents the design of a novel reflective linear-to-circular polarization conversion metasurface (PCM) and its application to a wideband high-gain circularly polarized (CP) antenna. The proposed PCM efficiently converts incident linearly polarized (LP) waves into CP waves within an ultra-wideband range of 11.8-28.6 GHz, thereby laying a solid foundation for the design of the wideband CP antenna. By adding an LP microstrip antenna as the feed source above the PCM, the metasurface leverages its polarization conversion capability to reflect CP waves, simultaneously enhancing the antenna gain, and thus yields a wideband high-gain CP antenna. The designed CP antenna exhibits an impedance bandwidth and a 3-dB axial ratio (AR) bandwidth both spanning from 13.2 to 18.6 GHz, corresponding to a relative bandwidth of 34%. Notably, the 3-dB AR bandwidth perfectly matches the impedance bandwidth. Meanwhile, the antenna maintains a stable high gain exceeding 11 dBi across the entire operating bandwidth. Excellent agreement is achieved between the measured and simulated results, confirming that the proposed antenna simultaneously achieves a wide CP operating bandwidth, full-band 3-dB AR coverage, and high gain. Such characteristics make it highly valuable for potential applications requiring both wideband CP operation and high gain, such as microwave communications, precision radar, and satellite navigation systems.

This paper designed a circularly polarized (CP) horn antenna working at X frequency band in this paper. The stepped septum polarizer (SP) was used to convert the linear polarization into circular polarization for the discussed square horn antenna. The circularly polarized horn antenna designed in this paper was simulated by using the full wave electromagnetic simulation software, and the specific structure and parameters were provided. The voltage standing wave ratio (VSWR) was lower than 2 within the frequency range of from 8GHz to 8.25GHz. The simulated axial ratio (AR) at the boresight direction at frequency 8GHz was about 3dB. The simulated gains of the designed antenna were about higher than 17dBi within the frequency range of 8GHz to 8.2GHz. The design and simulation results of circularly polarized horn antenna in this paper can provide a reference for the practical engineering application.

To use circular microstrip antennas as circularly polarized radiators, perturbations such as slits are added to resolve degeneracy in the fundamental modes. In this paper, posts are inserted between the circular strip and the ground plane and the degeneracy is resolved. the theoretical investigations of this new circularly polarized microstrip antenna are discussed. In the derivation of the theoretical equations, the field is expanded in terms of Green's functions corresponding to the circular cavity region terminated by an admittance boundary. Numerical examples are given for the frequency characteristics of the axial ratio and the input impedance and for the post dimensions to resolve the degeneracy. the radiation patterns and gains are shown for this antenna. the theory has been confirmed by model experiments.

ABSTRACTNew designs of the circularly polarized micro-strip antennas (CPMSAs) based on tree fractal geometries are proposed, examined experimentally, and compared. The excellent circularly polarized (CP) radiation with minimum axial ratio (AR) of 0.26 dB is achieved by optimization of the key parameters (angle, length, and width) of the fractal trees etched on the ground plane. Parametric study revealed that the fractal tree defected ground structures (FTDGS) are responsible for satisfying the condition of CP operation. The micro-strip antennas with third iterative FTDGS and modified third iterative FTDGS are fabricated on FR4 substrate. The measured 10-dB return loss and 3-dB AR are 99 MHz (2.407–2.506 GHz) and 12 MHz (2.443–2.455 GHz), respectively, with stable gain of 4.52 dBic at 2.45 GHz, for third iterative FTDGS antenna. For modified third iterative FTDGS antenna, measured 10-dB return loss and 3-dB AR are 109 MHz (2.354–2.463 GHz) and 26 MHz (2.386–2.412 GHz), respectively, with gain about 4.62 dBic in the vicinity of center frequency 2.4 GHz. The proposed designs can be good candidates for the unlicensed 2.45 GHz industrial, scientific, and medical (ISM) band applications.

This paper is presenting two different microstrip antennas (LHCP and RHCP antennas). It can explain the effects of S-shape and Z-shape slots for left-hand circular polarization and right-hand circular polarization respectively. Both types of slots are used to convert linear polarized antenna into the circularly polarized antenna. It is simulated with the help of CST-2015 and HFSS2018 design software. The antenna is designed into two steps. At first step, a simple linear microstrip antenna is designed and with second step, slots are used for circular polarization. The operating simulated frequency in both types of software’s is 0.258 THz to 0.355 THz and having 11 % operating bandwidth with the axial ratio at 3 dB. All the results of both antennas are the same but only radiation patterns results are opposite in polarization. The paper also presents the parametric study of copper material thickness and substrate thickness of the antenna.

A number of studies on the characteristics of cylindrical rectangular and circular microstrip antennas have been available in the open literature. The investigations of cylindrical triangular microstrip antennas, however, are relatively scant. Since the triangular patch can be a good substitute for the rectangular patch in microstrip antenna and array designs, due to its physically smaller patch size than the rectangular and circular ones, the related studies become interesting and important. This motivates the present study. In this article, both the cavity-model and full-wave analyses of cylindrical triangular microstrip antennas are described. Curvature effects on the input impedance and radiation characteristics for the antenna with various cylinder radii at its fundamental TM/sub 10/ mode are analyzed. Measured input impedances and radiation patterns are also presented for comparison. In addition, curvature effects on the cross-polarization characteristics of a triangular microstrip antenna at the TM/sub 10/ mode are also analyzed.

A compact single asymmetric coplanar waveguide feed (ACPW‐fed) dual circularly polarized microstrip antenna that operates at 1.8, 3.9, and 5.2 GHz in the entire operating frequency band 600 MHz–6 GHz for the radar detection of the improvised explosive devices (IEDs) carried by a person is introduced. The proposed novel quasi‐omnidirectional antenna consists of single sided rectangular ring microstrip patch antenna. L‐shaped slots are etched at the two opposite corners of the rectangular ring, introducing new resonance and circular polarization waves at the mid and upper bands, respectively. The achieved dual half‐rectangular ring patch antenna (DHRR‐patch) is loaded with strips of various shapes delicately placed at the center of the radiator, providing new resonance at the upper band and the improvement of the CP features. The matching technique designed based on CPW 50 Ω microstrip transmission line combined with the dual broad band matching techniques through quarter‐wave transformer in conjunction with open stubs and distributed lumped element method constitutes the novelty of the study. Based on quasi‐TEM mn (q‐TEM mn ) mode, ACPW‐fed and CP‐slots are employed to generate CP radiations at the q‐TEM 11 and q‐TEM 21 modes, respectively, while the ground plane width is optimized to enhance axial ratio bandwidth (AR‐BW). Input impedance and radiation pattern calculations of the conventional structure using transmission line and cavity model‐based q‐TEM 01 mode are conducted, respectively. Numerical experiments of the studied monolayer antenna are carried out using Advanced Design System (ADS) Version 2009 environment software employing internal one‐port option to excite the antenna. The prototype of the proposed antenna with a compact dimension (0.27 λ g × 0.38 λ g × 0.02 λ g at 1.8 GHz where λ g is the guided wavelength of the q‐TEM 01 mode) is fabricated on high loss laminate FR4 substrate of volume 43 × 38 × 1.6 (mm 3 ) and relative dielectric constant of 4.4 with simple laboratory‐based traditional printed circuit board (PCB) etching process. Measurement results show a fractional impedance bandwidth (FIBW) of 11.1%, 5.9%, and 7.1%, axial ratio (AR) of 4.6, 2.2, and 0.5 dB, and peak gain of 3.7, 4.7, and 6.1 dBic at 1.8, 4.0, and 5.2 GHz, respectively, demonstrating its suitability for IED detection applications. To verify the efficiency of the proposed model, measured results are compared with the simulated results and good agreement has been established.

In this paper, single-element and MIMO microstrip antenna with two pairs of unequal slits is proposed as a circularly polarized antenna with negligible back radiation for 5G mid-band handsets. The unequal pairs of slits are engraved on the antenna patch to guarantee the presence of the circular polarization (CP). The proximity-coupled feeding technique is used to excite the proposed microstrip antenna in order to provide larger antenna −10 dB bandwidth which approaches 10.8% (3.48–3.87 GHz). A novel analysis technique is proposed in this paper that demonstrates the 3D axial ratio pattern in order to generate CP in the broadside direction without affecting the structure of the ground plane which ensures weak back radiation. The 3 dB axial ratio bandwidth (ARBW) is found to be equal to 4.1% extended along the range (3.58–3.73 GHz). To make the design more compatible with the 5G mid-band handsets, the 2 × 2 MIMO structure of the proposed antenna with reduced mutual coupling (less than −20 dB) is also presented in this work. The simulation and measured results are in good agreement, and both verify the CP characteristics and the weak back radiation of the proposed antenna.

A low-profile single-fed, wideband, circularly-polarized slot antenna is proposed. The antenna comprises a square slot fed by a U-shaped microstrip line which provides a wide impedance bandwidth. Wideband circular polarization is obtained by incorporating a metasurface consisting of a 9 × 9 lattice of periodic metal plates. It is shown that this metasurface generates additional resonances, lowers the axial ratio (AR) of the radiating structure, and enhances the radiation pattern stability at higher frequencies. The overall size of the antenna is only 28 mm × 28 mm (0.3 λo × 0.3 λo). The proposed antenna shows an impedance bandwidth from 2.6 GHz to 9 GHz (110.3%) for |S11| > −10 dB, and axial ratio bandwidth from 3.5 GHz to 6.1 GHz (54.1%) for AR > 3 dB. The antenna has a stable radiation pattern and a gain of greater than 3 dBi over the entire frequency band.