Circularly Polarized Microstrip Antenna Research Articles

Compact Circularly Polarized Microstrip Antenna With Cross-Polarization Suppression at Low-Elevation Angle

This letter presents a method of cross-polarization suppression at low-elevation angle for a compact circularly polarized (CP) microstrip antenna. The compact CP antenna adopts a circular radiation patch with a crossed slot to reduce the dimensions, and a four-feeding-point technique is utilized to excite the patch for CP operation. The height and the diameter of the compact CP antenna are $0.064\, \lambda $ and $0.264\, \lambda $ ( $\lambda $ is the free-space wavelength at 1.2 GHz). At the outside of the CP antenna, a compact meander-line ring cavity (MLRC) structure is introduced, which can reduce the cross polarization from –14.2 to –26.1 dB in horizontal direction and increase 3-dB-axial-ratio (AR) ( ${\text{axial}\; \text{ratio}} \leq {\text{3 dB}}$ ) beamwidth from 128° to 192°. The height and diameter of the cavity are just $0.064\, \lambda $ and $0.448\, \lambda.$ Through the experimental validation, the impedance bandwidth of the proposed antenna for VSWR ≤ 2 is 20.8%, and the CP bandwidth for axial ratio ≤ 3 dB is 8.5%. Because of the MLRC, the cross polarization at low-elevation angle is clearly suppressed and the level at $\theta = \pm 90^\circ $ is not more than –23.2 dB. The 3-dB AR beamwidth reaches 190°. In the operating band, the peak gain of 5.3 dBic is also obtained.

A Sequentially Rotated, Circularly Polarized Microstrip Antenna Array with Reduced Mutual Coupling

ABSTRACTA circularly polarized microstrip patch antenna array with sequential rotation and reduced mutual coupling between its elements is proposed. A microstrip patch modified to suppress surface waves is used as the array element. The modifications include the addition of shorting pins and inclusion of a slot and edge truncations to produce a circularly polarized array element that does not excite surface waves. The designed element has higher gain and a more directional radiation pattern than a similar conventional microstrip patch antenna. In order to improve circular polarization bandwidth, sequential rotation techniques using the proposed microstrip antenna were investigated. Surface wave supersession of a 2 x 2 sequentially rotated array using the proposed design was achieved throughout the entire axial ratio bandwidth. One-layer directly fed array and two-layer aperture coupled array were investigated. The two-layer design achieved better impedance and axial ratio bandwidths than the single layer design. The design procedure, simulation results, and experimental measurements are presented.

Analysis and Design of Intrinsically Dual Circular Polarized Microstrip Antennas Using an Equivalent Circuit Model and Jones Matrix Formulation

Planar dual circular polarization (CP) antennas can be realized with a linearly polarized antenna and a quadrature hybrid, but the hybrid is lossy and undesirable for satellite communications applications where efficiency is paramount. There are surprisingly few hybrid-free, intrinsically dual CP microstrip antenna (MSA) designs in the literature. One reason for this is that it is challenging to obtain high isolation between ports while maintaining low return loss and good polarization quality. To resolve this problem, a method for multicriterion design optimization of dual-CP MSAs is proposed. The method is based on an accurate equivalent circuit model combined with a Jones matrix representation of the antenna response. The model explains the counter-intuitive tradeoff between cross-polarization isolation and impedance mismatch factor. The model also provides an analytical relationship between axial ratio bandwidth and impedance bandwidth, and allows the Wheeler cap method to be generalized to multiport, dual polarization antennas. Based on insights provided by the analysis, an effective matching and decoupling scheme is proposed, leading to an intrinsically dual CP MSA design that is competitive in performance with a dual linear antenna combined with a hybrid. Results are validated by comparison to full wave simulations for practical dual CP antenna examples.

Single-Feed Superstrate Loaded Circularly Polarized Microstrip Antenna for Wireless Applications

The paper presents three single fed circularly polarized square patch antenna structures for wireless communication applications. The antennas resonate from 1.5 to 1.8 GHz and can cover L-band GPS and GSM 1800 band. The antenna-1 consisting of four slits introduced at the boundary of radiating square patch with a cross slot in the centre. The antenna-2 exhibits four slits, a cross slot in the centre with radiating square patch protected using dielectric superstrate. A wider impedance bandwidth of 100 MHz is achieved with superstrate loading. Also, the antenna gain is improved up to a maximum level of 7 dB within the band of operation. Further, stacking of antenna-1 is done using conventional square patch as the parasitic element. The dual-band resonating antenna-3 is achieved with circular polarization in both of the frequency bands. The 3-dB axial ratio bandwidth is 1.1 % for the upper band and 1.3 % for the lower band. Proposed structures are fabricated on the FR-4 epoxy substrate and fed using SMA connector. The measured results are in good agreement with the simulated results.

ANALYSIS PERFORMANCE OF SINGLY-FED CIRCULARLY POLARIZED MICROSTRIP ANTENNA FOR WIRELESS COMMUNICATION

The circularly polarized (CP) microstrip antennas, both of singly- and doubly-fed types, possess inherent limitation in gain, impedance and axial-ratio bandwidths. These limitations are caused mainly by the natural resonance of the patch antenna which has a high unloaded Q-factor and the frequency-dependent excitation of two degenerative modes (TM01 and TM10) when using a single feed. Many applications which require circular polarization, large bandwidth, and good performance, especially in the field of wireless communication, are still difficult to be designed by using antenna software. Some consideration to take will include the application target and design specification, the materials to be used, and the method to choose (formula, numerical analysis, etc). This paper explains and analyzes the singly-fed microstrip antenna with circular polarization and large bandwidth. This singly-fed type of microstrip antenna provides certain advantage of requiring no external circular polarizer, e.g. the 900 hybrid, as it only needs to apply some perturbation or modification to a patch radiator with a standard geometry. The design of CP and large-bandwidth microstrip antenna is done gradually, by firstly truncating one tip, then truncating the whole three tips, and finally modifying it into a pentagonal patch structure and adding an air-gap to obtain larger bandwidths of impedance, gain and axial ratio. The last one antenna structure results in a novelty because it is a rare design of antenna which includes all types of bandwidth (impedance, gain, and axial ratio) being simultaneously larger than the origin antenna. The resulted characteristic performance of the 1-tip (one-tip) antenna shows respectively 1.9% of impedance bandwidth, 3.1% of gain bandwidth, and 0.45% of axial-ratio bandwidth. For the 3-tip (three-tip) step, the resulted bandwidths of respectively impedance, gain, and axial ratio are 1.7%, 3.3% and 0.5%. The pentagonal structure resulted in the bandwith values of 15.67%, 52.16% and 4.11% respectively for impedance, gain, and axial ratio.

Wide Beam Circularly Polarized Microstrip Antenna with Parasitic Ring for CNSS Application

Wide Beam Circularly Polarized Microstrip Antenna with Parasitic Ring for CNSS Application

Bandwidth Enhancement of a Single-Feed Circularly Polarized Antenna Using a Metasurface: Metamaterial-based wideband CP rectangular microstrip antenna

Wireless systems manufacturers desire a low-profile, wideband, circularly polarized (CP) antenna. Generally, a single-feed CP microstrip antenna (CPMA) has a simple configuration but is hindered by a narrow, 3-dB axial ratio (AR) bandwidth. The bandwidth of a multiple-feed CPMA can be enhanced but requires a complicated and larger feeding network. Many techniques have been employed to improve AR bandwidth, such as using dual-feed, network-based structures [1], stacked patches [2]?[3], array antennas with sequential feeding network [4], and multilayered structures [5]. However, these CP antennas are based on multiradiating patches or complicated feeding structures.

A circularly polarized square microstrip parasitic antenna with an improved bandwidth

ABSTRACTThis paper presents a novel design for an optimized circularly polarized microstrip antenna. Circular polarized microstrip antennas have many uses due to its low profile design. However, one of the microstrip antenna's main limitations arises from its narrow frequency bandwidth. Therefore, it is necessary to use special design techniques in order to increase the operating frequency bandwidth while maintaining all of the other respectable optimum radiation characteristics. The proposed design involves using a dual‐feed square patch, which is gap coupled with two parasitic patches in a mirrored L‐shaped configuration. This design resulted in an axial ratio bandwidth of 11%, S11 bandwidth of 14% and a gain of 9 dB at the 2.15 GHz center frequency. The proposed design was built, and the measured results were in agreement with the simulation results. Additionally, this antenna design was used in an array structure in order to increase the gain, while maintaining a good axial ratio. These enhanced radiation results allow the use of the proposed antenna design in many domains such as wireless and military applications without facing the limitations of the narrow frequency bandwidth. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:597–603, 2016

Dual-Band Dual Circularly Polarized Microstrip Antenna With Two Eccentric Rings and an Arc-Shaped Conducting Strip

In this letter, a novel low-profile dual-band and dual circularly polarized (CP) microstrip antenna is proposed. The antenna consists of two circular eccentric rings (CECRs) with different sizes. The two eccentric rings each work as a single-band circular polarization radiator and are simultaneously excited by an arc-shaped strip. A lumped equivalent circuit model is developed to analyze the operation mechanism of the antenna. In order to simplify the design procedure, empirical formulas are derived based on the physical parameters of the antenna. The proposed structure has been examined by both simulation and experiment, and both results agree very well.

A COMPACT CIRCULARLY POLARIZED MICROSTRIP ANTENNA WITH BANDWIDTH ENHANCEMENT

A novel compact circularly polarized microstrip antenna (CPMA) with bandwidth enhancement is proposed and studied. By employing capacitive loading and inductive loading, the size miniaturization is achieved. The cross-shaped aperture in the ground plane is able to excite two orthogonal modes. The near-equal amplitudes and 90 ◦ phase difference between these two modes are realized by properly designing the feed network, i.e., a 0 ◦ -90 ◦ hybrid comprising a 3-dB Wilkinson power divider cascaded with a 90 ◦ phase shifter. The proposed antenna exhibits a global bandwidth of 11.5% ranging from 1.88 GHz to 2.11 GHz with an overall size 50 mm × 50 mm × 6. 8m m (0.33λ0 × 0.33λ0 × 0.045λ0). The global bandwidth is defined where return loss is larger than 10 dB, broadside axial ratio (AR) smaller than 3 dB, and gain above 0 dBic.

High-Efficiency Compact Circularly Polarized Microstrip Antenna With Wide Beamwidth for Airborne Communication

The letter presents a compact circularly polarized (CP) microstrip antenna for airborne communications. The antenna adopts a square radiation patch with a cross slot to reduce the antenna dimensions and improve the impedance matching. For the high radiation efficiency of the proposed antenna, the no-resistor series feeding network is utilized to construct the antenna. In addition, the proposed structure also brings a super-wide beamwidth in axial ratio (AR) radiation patterns. To confirm the performances of the novel structure, an L-band prototype of the antenna is manufactured and tested. The thickness and the side length of the antenna are $0.073{\lambda _0}$ and $0.275{\lambda _0}$ , respectively ( ${\lambda _0}$ is the wavelength in free space). The impedance bandwidth for ${\rm VSWR} \leq 2 $ reaches 22.4%, and the AR bandwidth for ${\rm AR}\leq3 \hbox{dB}$ reaches 6.8%. In the overlap band, the radiation efficiency of more than 97% and the gains of more than 5.2 dBic are obtained. Especially, the beamwidth for ${\rm AR} \leq 3 \hbox{dB} $ can cover more than 180°.

A CIRCULARLY-POLARIZED MICROSTRIP ANTENNA WITH QUAD-BAND COMBINATION

In this paper, a novel quad-band combination of circularly-polarized microstrip antenna is proposed. This antenna has multi-frequency and quad-polarization with multiple coaxial probes, which cover four bands of the BeiDou navigation system (BDS), meeting different application requirements. By using a stacked structure to achieve feed and using symmetrical slotted method to place the coaxial probes, the multi-frequency antenna is connected together through the middle co-aperture. Meanwhile, the feed position and size are constantly optimized until get the most suitable one, and the necessary perturbation is obtained. We also introduce a broadband stripline 90 ◦ bridge. Ultimately, the circularly-polarized and multi-frequency operation is achieved. Furthermore, the novel design enables easy implementation, miniaturization, wide band, which can meet the application requirements and promote the development of the BDS, which can be combined with the Internet of Things technology, applied to life and production.

Hybrid Coupled Feed Circularly Polarized Patch Antenna for Military Applications

A new configurable circular patch antenna for Military applications fed by 50Ω impedance hybrid coupler feed is examined here. The dual fed circular polarized microstrip antenna is etched on a Rogers with dielectric substrate of 2.2 with the height of 0.16 mm. The effect of hybrid coupling is circular polarization and radiation around 360 degree. The thickness of Circular patch antenna is of 0.381mm. The antenna is designed to achieve high gain of 6dB at the operating frequency of 8GHz. Simulation results and the measured results characteristic are closely matches with each other.

Wideband Conical-Beam Circularly Polarized Microstrip Antenna for Large Ground Plane

A wideband conical-beam circularly polarized (CP) microstrip antenna for an electrically large platform is investigated. The antenna structure simply consists of a center-fed patch and eight shorting vias each of which is surrounded by a modified elliptical-ring slot. The ${\theta}$ -polarization of the proposed antenna is provided by the shorting vias and the coaxial probe, while the ${\varphi}$ -polarization is generated by the modified elliptical-ring slots. Moreover, the amplitudes of the two orthogonal polarizations can be controlled separately and are less sensitive to the size of the metal platform. By employing the even and odd modes of the elliptical-ring slot, the proposed antenna exhibits a wide impedance bandwidth. A prototype of the antenna is fabricated and mounted on three ground planes, which function as electrically large metal platforms, with the radii of ${\lambda}_{0}$ , $2{\lambda}_{0}$ , and $10{\lambda}_{0}$ . The measured results show that the wideband CP antenna with these three ground planes have the 10-dB impedance bandwidths of 19.4%, 19.5%, and 19.9%, and the corresponding 3-dB axial ratio (AR) bandwidths of 25.3%, 25.6%, and 24.8%, respectively. A detailed analysis on the radiation characteristics is also carried out for small to extremely large ground plane extensions.

Optimized Performance Result for 2.4 GHz and 2.45 GHz Circularly Polarized Microstrip Antenna

Optimized Performance Result for 2.4 GHz and 2.45 GHz Circularly Polarized Microstrip Antenna

Bandwidth enhancement for single‐feed circularly polarised microstrip antenna with epsilon‐negative transmission line‐based annular ring

A novel low-profile single-feed circularly polarised (CP) microstrip antenna (MSA) loaded by a coplanar parasitic epsilon-negative (ENG) transmission line (TL)-based annular ring with enhanced bandwidth is proposed. By exciting the TM11 modes on both the driven patch and the coupled ENG TL-based annular ring, two minimum axial-ratio (AR) points are generated. It is the combination of the two minimum AR points that result in the bandwidth enhancement. An antenna prototype operating at the WLAN 5.2 GHz band is exemplified to validate the proposed concept. The measured results show that the proposed antenna with a low profile of 0.035λ 0 obtains an overlapped bandwidth (return loss <−10 dB and AR < 3 dB) of 4%, which is 2.3 times wider than the conventional CP MSA. Moreover, the proposed antenna exhibits higher gain and lower backward radiation as compared with conventional CP MSAs.

Design and testing of a compact circularly polarised microstrip antenna with fractal defected ground structure for L‐band applications

A compact circularly polarised (CP) microstrip antenna for mobile satellite communication band of India (1.492-1.518 GHz) is presented. Two asymmetric length rectangular shape slots, perpendicular to each other are printed on the circular patch for realisation of CP radiation. To improve the performance parameters of patch antenna such as axial ratio (AR) bandwidth, return loss bandwidth, radiation efficiency and so on a new technique of combination of fractal theory and defected ground structure (DGS) is proposed for the first time in design of CP antennas. 44.74% size reduction in patch size, enhancements of 62.73% in AR bandwidth, 70.74% in return loss bandwidth and 4.03% in radiation efficiency is achieved as compared with conventional patch antenna, after incorporation of Koch curve fractal DGS in the ground plane. The performance of the developed antenna has been compared with other available L-band planar antennas in the literature, and it is found that the developed structure is better one in many aspects. Laboratory prototype of the antenna is fabricated and experimentally measured for cross verifying the simulated results.

Reconfigurable circularly polarized microstrip antenna based on dual‐embedded dual slotted ring perturbation

ABSTRACTThis article describes a new reconfigurable circularly polarized microstrip antenna using a dual‐embedded dual slotted ring perturbation. The proposed antenna consists of three single slotted rings at each corner in the ground plane and one dual slotted ring with two PIN at the residual corner where the large‐sized ring in the front patch side and the small‐sized ring in back ground side. The dual slotted ring perturbation can generate and alternate circularly polarized waves by changing the effective size of the dual slotted ring. To investigate the effect of the dual slotted ring, the dominant slotted ring at the patch side is analyzed and implemented. The measured results of the proposed antenna show a good agreement with the simulation and demonstrates circularly polarized radiations and their reconfigurable capabilities. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:2422–2425, 2015

Design and characterization of an efficient multi-layered circularly polarized microstrip antenna

A novel asymmetric “+” shaped fractal slotted circularly polarized microstrip antenna with a Yagi–Uda structure is proposed. Four asymmetric plus shape slots are embedded symmetrically in the center of all four quadrants of a square patch. To suppress undesirable higher modes, dumbbell-shaped defected ground structure (DGS) is introduced at the ground layer of the antenna. We introduce a method to compensate the reduction in gain occurring due to the presence of DGS, without changing in the overall size of the antenna. A 3 dB axial ratio bandwidth of 4 MHz at center frequency of 862 MHz, 10 dB impedance bandwidth of 13.20 MHz and a gain of 4.25 dB is achieved with the proposed antenna. A laboratory prototype of the proposed antenna is made to cross-verify the simulation results. Very good agreements between the two are obtained. The proposed antenna may prove useful for International Mobile Telecommunication application for designing high-gain arrays.

Tri-band dual circularly polarized planar antenna with defective ground structure for wireless applications

A novel tri-band asymmetric slot with defective ground structure (DGS) microstrip antenna for dual circular polarization (CP) is proposed. By placing a slot with 45° across diagonally at the center of the patch, excites resonant bands with narrow bandwidth and dual CP operation. The main design challenge is to introduce optimized defected element of circular dumbbell shape to enhance the impedance bandwidth with frequency shift operation at all bands. DGS enabled antenna is practically fabricated and simulated. Antenna is compact in size and shows a good quality of CP at two resonant bands and linearly polarized at one band. Structure displays the impedance bandwidth of 8% (2.26–2.45 GHz), 5.45% (3.41–3.6 GHz) and 3.07% (5.12–5.28 GHz). The design also shows 40 and 11 MHz, 3-dB axial ratio bandwidth at lower and middle bands, respectively. Simulated gain for each band is 4.72, 6.2 and 4 dB. Performance of antenna with and without DGS is also studied and compared. This single probe feed proposed antenna remains consistent with good radiation patterns and sufficient antenna gain over the operating bands. Excellent agreement was obtained between measurements and simulations.