Circular Patch Radiator Research Articles

A Low-Profile and Stacked Patch Antenna for Pattern-Reconfigurable Applications

A low-profile stacked patch antenna is proposed for pattern-reconfigurable (PR) applications. A referential circular radiation patch with desired conical beams and broadside beams operation is analyzed. However, due to bad port isolation, slant radiation patterns with high cross-polarization levels occur. Suspended pin loading and gap-coupled feeding techniques are introduced to achieve better port isolation, which leads to stable radiation patterns and low cross-polarization levels. Meanwhile, in order to broaden the operation bandwidth, two stacked square patches integrated with a T-shaped feeding branch are utilized and analyzed for exciting low-frequency resonances at the broadside mode. By controlling the p-i-n diodes implanted in the feeding network, reconfigurable conical and broadside beams are obtained. The measured results show that the proposed antenna yields a 10 dB operation impedance bandwidth of 11%, ranging from 2.41 to 2.69 GHz. The peak gains operating at the conical state and broadside state are 4.5 and 7.7 dBi, respectively. The overall profile of the proposed antenna is only 0.07λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> , where λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> is the free space wavelength at 2.55 GHz.

A Low-Profile Antenna With Omnidirectional and Unidirectional Radiation Patterns Over Two Operation Bands

A compact low-profile dual-band antenna with a single circular radiation patch is presented. The circular radiation patch is top-loaded by a metal strip, leading to a zeroth-order resonant (ZOR) mode with monopole-like radiation pattern at the lower operation band, and the ZOR mode is not affected by the position change of the probe feed. Thereby an off-center probe feed can be used to excite a TM01 mode with patch-like radiation pattern at the upper operation band, and its performance remains good stability when the size of the metal strip is varying. The equivalent circuit, electric field and current distributions of the proposed antenna are studied to investigate the principles of the ZOR and the TM01 modes, and all the results show that the two operation bands can be effectively and independently controlled. As a proof-of-concept, a circular patch antenna prototype with low profile of about $0.023~\lambda _{0}$ at 2.35 GHz is fabricated and tested. Good agreements between the measured and simulated results are achieved, showing monopole-like and patch-like radiation patterns within 2.28 - 2.40 GHz and 3.30 - 3.60 GHz, respectively, and the average realized gains are about 2.5 dBi and 8.5 dBi for the two operation bands.

Dual Band Slotted Printed Circular Patch Antenna With Superstrate and EBG Structure for 5G Applications

Slotted circular printed layered patch antenna is designed, simulated and fabricated for 5G (Fifth Generation) wireless communication applications. The antenna consists of slots in the main radiating circular patch element for miniaturizing the size of the radiating element and providing dual band radiation characteristics. The feed line is separated on bottom substrate layer with EBG (Electromagnetic Band-Gap) embedded for enhancing the gain characteristics of the antenna. Superstrate layer is also used for improving the gain of the antenna where the distance from the radiating antenna element is optimized for maximizing the impedance bandwidth and radiation characteristics. The feed realization and impedance matching of the radiating slotted circular patch antenna is done by inducing slot at the middle ground plane of the slot embedded circular patch antenna system. The proposed configuration provides power radiation gain values of more than 5 dB for the Ka band of communications, whereas the impedance bandwidth of the antenna is verified for the dual resonances at 27.5 and 28.5 GHz. Dual band radiation characteristics are attained by embedding and optimizing the slot length and width in the circular patch radiator element that is placed on the upper face of the substrate RT Rogers Duroid 5880 layer. The length of the microstrip feed line embedded in the lower layer of the substrate is optimized for providing required bandwidth characteristics for the dual frequency point radiations. The antenna configuration is designed, modeled and simulated in CST (Central Standard Time) Microwave studio. The antenna is fabricated and measured vs simulated frequency response, gain patterns and current density plots are presented for the verification of antenna operation in the desired frequency bands.

Three‐layered circular patch antennas array with UC‐PBG for wider bandwidth and surface wave propagation mode attenuation at X‐band

AbstractIn this work, a three‐layered antenna array complemented with Uniplanar Compact Photonic‐Bandgap (UP‐PBG) structure is presented, for applications in the X‐band. The proposed array consists of circular patch radiator operating at 10 GHz, where the element is surrounded by UC‐PBG unit cells in order to improve the performance of the antenna. By combining the radiator and the UC‐PBG cells, the directivity, gain and polarization are kept, while the parasitic lobes are reduced 50% their magnitude. The bandwidth augments 44% compared to a conventional array, and a diminution of the surface propagation mode is obtained, increasing the radiation efficiency.

A compact multilayer wide-band and high-gain circularly polarized antenna

In this paper, we present a high-gain wide-band circularly polarized antenna that uses double circular radiation patches and a double Y-shaped slot fed by microstrip line. The antenna consists of four layers stacked on top of each other and spaced by air gaps. In proposed antenna a copper layer is used as a reflector for directing radiation patterns, increasing front to back ratio (FBR) and gain. Three other layers include radiation patches with the same dimensions. Second layer includes a microstrip feed line on one side and a double Y-shaped slot on its other side. Third and fourth layer include circular radiation patches for controlling the polarization and bandwidth of the proposed antenna. Right-hand circular polarization {is obtained by optimizing} the dimensions of the circular patches. {Measured frequency bandwidth ranges from 3.35 GHz to 6.45 GHz, with} an S11 less than -10 dB. {Moreover, axial ratio and gain} are less than 3 dB and more than 7.5 dBi, respectively.

Generalized design approach to compact wideband multi-resonant patch antennas

In this work, a generalized design approach to compact, wideband multi-resonant microstrip patch antenna is proposed. Theoretical criterion of the length of the prototype dipole is laid down based on the simplest dipole model and the associated eigenmodes at first. Then, the criterion is employed to reveal the general relationship between the prototype dipole length, operational modes, sizes, and radiation behaviors of the resultant multi-resonant circular sector patch antennas. Next, a compact wideband, dual-resonant circular sector patch antenna is designed accordingly. It is operating at the TM3/4,1 and TM9/4,1 modes within a 240° circular sector patch radiator with its radii short circuited. The antenna fabricated on a single-layered air substrate exhibits an available radiation bandwidth of 25.0%, with a profile as small as 0.043 guided wavelength at the center frequency. It is evidently verified that the approach can be employed to realize compact, dual-resonant wideband microstrip patch antennas without increasing antenna profile, inquiring multiple radiators or employing reactance compensation techniques. In addition, it may lead to a series of novel wideband patch antenna designs with diverse performances.

Pin‐loaded circularly‐polarised patch antenna with sharpened gain roll‐off rate and widened 3‐dB axial ratio beamwidth

A circularly-polarised patch antenna with the loading of shorting pins is proposed in this study to sharpen the gain roll-off shape and widen the 3-dB axial ratio beamwidth (ARBW). First of all, it is theoretically revealed that when the electrical size of a circular patch radiator is appropriately constituted, the radiation gain at the horizon can be significantly suppressed and the axial ratio can be maintained below 3 dB over a wide angular range. By introducing a set of metallic pins, which short the patch in a circular contour, the resonant frequency of the antenna will be increased. In this way, the patch radius with respect to wavelength can be freely chosen, so that sharp gain roll-off rate and wide ARBW can be simultaneously achieved. After the extensive analysis is executed, two circular patch antennas with and without loading of shorting pins are designed, fabricated and tested for comparison. Simulated and measured results show that the gain roll-off is enhanced up to near 20 dB and 3-dB ARBW is extended to around 140° so as to effectively reduce the undesired multipath interference as highly demanded in the application of global navigation satellite system.

Design Approach to a Novel Dual-Mode Wideband Circular Sector Patch Antenna

A design approach to a novel wideband circular sector patch antenna is proposed. Design guidelines are laid down based on an approximate 1.5-wavelength, multimode magnetic dipole, and the cavity model. Then, the flared angle of the circular sector patch and the corresponding usable resonant modes for wideband radiation are determined. It is demonstrated that the resonant TM4/3,1 and the TM8/3,1 modes within a 270° circular sector patch radiator can be simultaneously excited, perturbed, and employed to form a wideband unidirectional radiation characteristic with two resonances. Prototype antennas are designed and fabricated to experimentally validate the dual-resonant wideband property on a single-layered substrate. It is further demonstrated that the antenna designed on a 5-mm-thick air substrate exhibits an available radiation bandwidth (ARB) of 14.5%, while the printed one designed on a 2-mm-thick modified Teflon substrate exhibits an ARB of 6.5%. It is evidently validated that the proposed approach can be employed to effectively enhance the operational bandwidth of microstrip patch antennas without increasing antenna profile, inquiring multiple radiators or employing reactance compensation techniques.

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 simple planar monopole UWB slot antenna with dual independently and reconfigurable band-notched characteristics

An extremely simple and compact planar monopole ultrawideband UWB slot antenna with dual band-notched characteristics is proposed. The antenna is composed of a circular radiation patch, a microstrip-fed line, and a partial ground. By etching an arc-shaped slot on the radiation patch and a C-like slot on the feed line, dual notched frequency bands at 3.3-3.7 GHz for WiMAX and 5.15-5.825 GHz for WLAN are achieved. And, the two notched bands can be adjusted independently by varying the length of the slots. Moreover, the band-notched characteristics can be reconfigurable by shorting the corresponding slots. So, the antenna is capable of operating in one of multiple modes which makes it an excellent candidate for UWB applications. Meanwhile, experimental results indicate that the antenna has an available impendence bandwidth from 2.9 to 11 GHz which covers the UWB frequency band, and nearly omnidirectional patterns, stable gains, small group delay in operating band except rejected bands. © 2014 Wiley Periodicals, Inc. Int J RF and Microwave CAE 24:706-712, 2014.

Miniaturized CPW-FED UWB antenna with dual frequency rejection bands using stepped impedance stub and arc-shaped parasitic element

In this article, we propose the design of a coplanar waveguide (CPW)-fed circular slot antenna, with dual frequency rejection characteristics for ultra-wideband communication applications. The dual frequency rejection function is realized by inserting a stepped impedance stub (SIS) inside the circular ring radiation patch and by using an arc-shaped parasitic element (ASPE) along the circular ring radiation patch. The center frequencies of these rejection bands can be controlled by adjusting the dimensions of the SIS and the ASPE. The antenna has been designed, optimized, and fabricated, and its performance has been verified through measurements, which show that it can operate across a wide bandwidth ranging from 2.7 to 11.6 GHz with a VSWR < 2, and that it provides dual-band rejection characteristics at both the WLAN band and the X-band. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:783–787, 2014

A CPW-fed circular slot UWB antenna with WLAN band and X-band filtering characteristics using hybrid resonators

A compact coplanar waveguide (CPW)-fed circular slot ultrawideband (UWB) antenna with dual-band filtering characteristic is presented in this article. The dual-band filtering characteristic is achieved by inserting an arc-rectangle-shaped stepped impedance resonator in the circular ring radiation patch and etching a spiral stepped impedance resonator in the CPW-fed transmission line. The numerical and experimental results demonstrate that the proposed antenna can operate on a frequency band between 2.7 and 12 GHz with voltage standing wave ratio less than 2, except for that two filtering bands between 4.8 and 6 GHz and between 7.6 and 8.6 GHz are used to prevent the potential interference from WLAN band and X-band. In addition, the proposed antenna has a compact size and omnidirectional radiation pattern, which is suitable for UWB communication applications. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:925–929, 2014

A compact band‐notched ultrawideband dielectric‐loaded antenna

ABSTRACTA compact ultrawideband (UWB) dielectric‐loaded antenna with band notched characteristics is presented. The antenna consists of the circular metal radiation patch fed by a 50‐Ω microstrip transmission line and a rectangular ground plane with cutting a notch to achieve UWB application. By etching a modified U‐shaped slot in the radiating patch and properly tuning its location and form, band rejected filtering properties in the WiMAX/WLAN bands can be achieved easily. The compact size of the proposed DRA can be reduced to 14.5 × 29 mm2 using a dielectric resonator (DR) above the modified circular radiation patch and possess band‐notched UWB characteristics. A good agreement has been obtained between simulation and measurement and it has good omnidirectional radiation patterns in H‐plane. Especially, the proposed band‐notched UWB loaded with GYA DR has excellent surrounding environment temperature stability. Base on these desirable features of the proposed band‐notched UWB dielectric‐loaded antenna, it is shown that it is a good candidate for various UWB applications. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:456–462, 2014

An Easily Realizable Band-Notched UWB Antenna

An easily realizable ultrawideband (UWB) monopole antenna, with band-notched characteristics, is presented. The antenna consists of a circular metal radiation patch, fed by a 50-Ω microstrip transmission line and a rectangular ground plane with a notch cut into it. By etching a modified U-shaped slot in the radiating patch and by properly tuning its location and form, band-rejected filtering properties can be achieved easily in WiMAX/WLAN bands. It has good omni-directional radiation patterns in H-plane and a good agreement between simulation and measurement.

A CPW‐Fed Circular Wide‐Slot UWB Antenna with Wide Tunable and Flexible Reconfigurable Dual Notch Bands

A coplanar waveguide (CPW)-fed circular slot antenna with wide tunable dual band-notched function and frequency reconfigurable characteristic is designed, and its performance is verified experimentally for ultra-wideband (UWB) communication applications. The dual band-notched function is achieved by using a T-shaped stepped impedance resonator (T-SIR) inserted inside the circular ring radiation patch and by etching a parallel stub loaded resonator (PSLR) in the CPW transmission line, while the wide tunable bands can be implemented by adjusting the dimensions of the T-SIR and the PSLR. The notch band reconfigurable characteristic is realized by integrating three switches into the T-SIR and the PSLR. The numerical and experimental results show that the proposed antenna has a wide bandwidth ranging from 2.7 GHz to 12 GHz with voltage standing wave ratio (VSWR) less than 2, except for the two notch bands operating at 3.8–5.9 GHz and 7.7–9.2 GHz, respectively. In addition, the proposed antenna has been optimized to a compact size and can provide omnidirectional radiation patterns, which are suitable for UWB communication applications.

A Novel Compact Ultra-Wideband Dual-Notch Microstrip Antenna

This article presents the results of a novel and compact ultra-wideband dual-notch microstrip antenna excited using a coplanar waveguide feed. The antenna is comprised of two circular radiation patches with a rectangular slot to enhance its impedance bandwidth and two open-circuit stubs that generate high attenuation notches at the desired frequencies. The notch frequency can be controlled by changing the length of the stubs. The proposed antenna exhibits an impedance bandwidth of 123% from 2.45 to 10.3 GHz, significantly satisfying the Federal Communication Commission's ultra-wideband frequency range, while showing the band rejection performance in the frequency bands of 3.3 to 3.8 GHz and 5 to 5.9 GHz. The antenna was fabricated on a standard dielectric substrate, and its measured results are used to verify the simulated performance. The empirical results indicate that the proposed antenna is well suited to be integrated within various portable devices for ultra-wideband operation.

A CPW-Fed UWB Antenna with C-band/WLAN/X-band Notch Functions using Isosceles Triangular Resonator and Stepped Impedance Resonator

A CPW-fed circular wide slot UWB antenna with C-band, WLAN and X-band notch functions has been presented in this article. The two stop bands are obtained by etching an isosceles triangular resonator with an inner isosceles triangular stub in the circular radiation patch and a stepped impedance resonator with an inner stub in the CPW fed transmission line. The two notched bands can be tuned by changing the dimensions of isosceles triangular, stepped impedance resonator and the inner stubs to give tunable notched band functions. The proposed dual notched band UWB antenna has been designed in details and optimized by means of HFSS. The proposed antenna has a small size of 32x24x1.6mm3. The simulated and measured results show that the designed UWB antenna has an impedance bandwidth of 10.7GHz covering the frequency band from 2.8GHz to 13.5GHz for voltage standing-wave ratio (VSWR) less than 2, except the notch bands 4.0GHz-5.4GHz for C-band and WLAN, 8.2GHz-9.3GHz for X-band which are used in satellite and military communications. The article also refers some recent patents on UWB antenna design. Keywords: Notch band, isosceles triangular resonator, stepped impedance resonator, UWB antenna, ANTENNA STRUCTURE, Impedance bandwidth, designed antennas

A wideband planar surface wave antenna for the WLAN router

In this paper, a wideband planar surface wave antenna for the 5 GHz wireless local area network (WLAN) router applications is proposed. The antenna is excited by a center-fed circular patch with an annular ring patch (ARP) and a thin dielectric slab with periodic circular patches (PCPs) is loaded on the circular patch radiator. A prototype of the 0.3-mm-thick ( 0.06 λ ) antenna was constructed and tested to evaluate its suitability for reducing router thickness. The impedance bandwidth of the antenna was 23.6% (5.7–7.1 GHz) and its average gain was 5.91 dB. The radiation pattern of the antenna was nearly omnidirectional.

Compact and Tunable Circular Microstrip Patch using Post-Varactor Loading

In this communication we present a novel configuration of varactor diode loaded circular microstrip patch antenna. The diode is connected between the upper patch and the ground plane via a thin inductive post. This results in reduction of resonant frequencies for all the modes of a circular patch radiator. This radiator is also widely tunable with the changing bias of varactor diode. The theoretical justification is also presented and the computed results are compared with experimental results.

Investigation of Modes Tunable Circular Patch Radiator with Arbitrarily Located Shorting Posts

Investigations presented reveal that the resonant frequencies of first few normal modes of a circular patch radiator can be predictably tuned by introducing multiple shorting posts distributed along the circumference of a circle concentric with the patch radiator. It also shows that by appropriate selection of location of shorting posts it is possible to design dual band antenna with flexible frequency separation between identical modes.