A new triple proximity-fed circularly polarized microstrip antenna

This paper presents a single-feed circularly polarized (CP) microstrip antenna achieved by defected ground structure. With the proposed DGS, a new resonant mode is added, which is orthogonal to the original resonant mode. These two modes will have the same magnitude and the 90° time-phase difference by adjusting the DGS dimensions, which contributes to achieve the CP radiation. Both the simulated and measured 10-dB impedance bandwidth of the CP microstrip antenna are 30 MHz, while the 3-dB axial-ratio bandwidth is 6 MHz. The CP gain across the 3-dB AR band ranges from 4.6 to 5.0 dBic.

A new technique to design single-feed circularly polarized (CP) microstrip antenna is proposed. The CP radiation is obtained by adjusting the dimension of the etched fractal defected ground structure (FDGS) in the ground plane. Parameter studies of the FDGS are given to illustrate the way to achieve CP radiation. The CP microstrip antennas with the second and third iterative FDGS are fabricated and measured. The measured 10-dB return-loss bandwidth of the CP microstrip antenna is about 30 MHz (1.558 to 1.588 GHz), while its 3-dB axial-ratio bandwidth is 6 MHz (1.572 to 1.578 GHz). The gain across the CP band is between 1.7 and 2.2 dBic.

A simple design of a probe-feed microstrip antenna with circular polarization (CP) radiation is presented. By embedding dual slits in a square microstrip and adjusting the sizes of the slits, an H-shaped microstrip antenna with two near-degenerate orthogonal modes for CP radiation can be achieved. This design provides a wide CP bandwidth and relaxed fabrication tolerances. Details of the antenna design are described, and theoretical and experimental results of the CP performance are presented.

In this communication, an S-band wide-bandwidth and wide-beamwidth full-metal circularly polarized (CP) cavity-backed slot antenna is proposed. A pair of triangular prisms placed at the corners of the cavity is introduced to produce TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">101</sub> and TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">011</sub> modes with orthogonal electric fields. These two modes are used to achieve the CP radiation and radiate the energy through a single-circular slot. By simultaneously varying the prisms' size and slot radius, the axial ratio (AR) bandwidth (ARBW) improves. The ARBW is further improved by replacing the circular slot with an elliptical slot. As a result, the ARBW increases from 1.0% to 10.3% without complicating the antenna structure and without enlarging the antenna size. Besides, the antenna still operates at two degenerate modes to introduce stable radiation gain and pattern. In addition, the proposed CP slot antenna features a wide ARBW. The final measurement shows that the proposed CP antenna can achieve a 9.5% bandwidth, a stable gain of 7.65 dBic ± 0.15 dBic, and higher than 140° ARBWs in a wide frequency range. The peak total radiation efficiency and aperture efficiency are about 97% and 91%, respectively.

In this article, a novel ultra-wideband circularly polarized (CP) orthogonal magnetic dipole (OMD) antenna array with a dual-mode sequential rotation feeding (SRF) networks is proposed for the millimeter-wave (mm-wave) applications. Above all, a novel OMD concept model is proposed. Subsequently, based on the conceptual model, a planar CP OMD antenna element is designed and analyzed, and its axial ratio (AR) bandwidth is enhanced by using parasitic patches. To further achieve a wider AR bandwidth and a higher gain, a dual-mode SRF network is proposed and designed to form a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$4\times4$ </tex-math></inline-formula> CP antenna array. Finally, the antenna array is fabricated and measured to verify the design. The measurement results of the proposed <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$4\times4$ </tex-math></inline-formula> CP array show a −10-dB impedance bandwidth of 88.3% (18.15–46.85 GHz) and a 3-dB AR bandwidth of 61.0% (20.5–38.5 GHz) with a peak gain of 16.8 dBic. The proposed antenna array boasts several advantages, such as wide impedance and AR bandwidths and ease of integration, making it suitable for a wide range of applications in fifth-generation (5G) mm-wave communication systems.

A wideband high-gain circularly polarized (CP) substrate integrated cavity (SIC) antenna array is presented for millimeter-wave applications. The proposed antenna element is simply composed of a slot-coupled high-order-mode resonant square SIC and a pair of obliquely placed strip-shaped parasitic patches on the top surface of the SIC. The parasitic patches are used to adjust the aperture electromagnetic field distribution and phase of the two orthogonal resonant modes of TM211 and TM121 in the SIC to achieve a high-gain CP radiation and meanwhile introduce an additional cavity-backed slot-dipole CP radiation to extend axial ratio (AR) bandwidth of the proposed antenna element. By combining the above two high-gain CP radiation mechanisms, a wideband high-gain CP SIC antenna element is achieved. The simulated results of the proposed antenna element show an overlaid bandwidth of 20.36% from 26.20 to 32.14 GHz, while considering the −10 dB reflection coefficient, 3 dB AR, 3 dB gain bandwidths properties, and a maximum right-hand CP gain of 10.53 dBi at 29.40 GHz. On this basis, a wideband high-gain 8 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times $ </tex-math></inline-formula> 8 CP array fed by a full-corporate substrate integrated waveguide (SIW) network is designed and fabricated. The measured results show that the proposed array has an overlaid bandwidth of 21.72% from 25.85 to 32.15 GHz and a measured gain of up to 26.10 dBic at 29.00 GHz.

A new circular‐polarization (CP) design of an annular‐ring microstrip antenna operating at the fundamental TM11 mode is presented. The CP radiation of the proposed design is achieved by connecting an L‐shaped strip to two orthogonal sides of the inner boundary of the annular‐ring patch. A prototype of the proposed antenna fabricated on a foam substrate has been implemented and studied. The results show that good CP‐radiation performances are obtained and the 3‐dB axial ratio is about 2%. Good agreement is also obtained between the measured and simulated results. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 42: 156–157, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20237

A new circular polarization microstrip antenna having a defected ground plane is presented in this paper. A defect on the ground plane is introduced by inserting a square ring slot just below one of the top corners of the patch. The inserted slot on the ground creates a perturbation in the patch as like as conventional perturbed circular polarization antennas. The measured 3-dB axial ratio bandwidth was 1.26% with a gain of around 6.1 dBic.

In this paper, a compact dual feed circularly polarized microstrip antenna (CPMSA) is presented using 3-dB 2-branch line coupler as feed network. The antenna size is reduced by 39.9% by cutting slots in circular shaped CPMSA. The antenna characteristics are analyzed using cavity enclosure and radome cover. It increases the antenna bandwidth (BW) and gain. The compact CPMSA provides 26.8% BW for |S 11 | ≤ -10 dB and 3 dB axial ratio (AR) BW of 27% with maximum gain of 6.9 dBi at 2.8 GHz. Cross polarization (X-pol) of lower than -15 dB and front to back ratio (FBR) of more than 12 dB are obtained for the compact CPMSA. The designed antenna is fabricated and experimental results agree well with simulated results. The designed antenna can be used as transmitter and receiver in transponder systems to monitor missile health parameters.

A broadband and compact size circularly polarized (CP) two-port multiple input multiple output (MIMO) antenna with a footprint of 25 mm <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times20$ </tex-math></inline-formula> mm is investigated. The designed oval-shaped MIMO antenna employs concentric rings with oval slots (CROS), along with a circular radiator and two open-ended parallel protruded stubs. The CP radiation is achieved by embedding three oval slots, in which two of them are deployed at the left and right side of the concentric rings, whereas the third one is deployed at the top section of the concentric rings. The measured 10-dB impedance bandwidth of the proposed MIMO antenna was 46.30% (3.12–5.00 GHz), and its corresponding 3-dB axial ratio bandwidth (ARBW) was 41.34% (3.30–5.02 GHz). Furthermore, very wide beamwidths of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$137^{\circ }\pm 0.2$ </tex-math></inline-formula> and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$154^{\circ }\pm 0.2$ </tex-math></inline-formula> were measured in the right-hand circular polarization (RHCP) and left-hand circular polarization (LHCP) radiation patterns, respectively. The minimum achieved isolation between the antenna elements is 18.50 dB without using any additional decoupling structure, and the calculated envelope correlation coefficient (ECC) < 0.03.

A high efficiency linear polarized antenna consisting of a patch fed cavity has already been developed for use in personal communication terminals. It possesses several desirable features for active array applications, particularly the ease of RF component integration and heat removal. As part of the continued development of this antenna, it is very desirable to extend the capabilities to include future circularly polarized (CP) applications. The logical step for achieving the CP performance is to replace the linearly polarized feed patch with a single point feed CP patch. A single point feed is preferred in order to maintain the simplicity of the feed network. This approach, however, has a major drawback of possessing a narrow axial ratio bandwidth. To improve the axial ratio bandwidth, an alternative CP feed antenna is required. Research in circularly polarized dielectric resonator antennas (DRAs) has shown that a wide axial ratio bandwidth can be achieved from a single point fed DRA. The performance of the dielectric cross within a cavity structure is investigated. The optimization of the geometry and the effects on overall operation are discussed.

Here, a small, CPW-fed monopole antenna with reconfigurable polarization is introduced. Two stubs positioned at each side of the monopole radiator are connected to the ground plane via two p-i-n diodes to achieve an asymmetric ground plane. Two horizontal slits inside the ground plane assist in increasing the impedance matching. The antenna either produces linear polarization or left/right circular polarization, depending on the p-i-n diode's switching state. The structure was fabricated, and its performance was evaluated to confirm the planned design. At 5.8 GHz frequency, the requisite S11 bandwidth (IBW) and axial-ratio (AR) bandwidth is attained by correctly incorporating the stubs and slitting the ground plane. Two C-shaped metal strip is loaded on top of the substrate layer to increase the AR bandwidth. The measured impedance bandwidth is 5.50-6.10 GHz (600MHz, 10.34%) and the AR bandwidth is 5.52-6.0 GHz (480MHz, 8.62 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">%</sup> ) for circular polarization and 5.25-5.81 GHz (560MHz,10.18%) impedance bandwidth for linear polarization. With a maximum CP gain of 3.8 dBic, the suggested antenna displays a nearly uniform gain over the operational AR bandwidth. The recommended antenna is appropriate for higher frequency WLAN applications and has a compact structure with a large 3dB AR bandwidth.

This letter presents a novel circularly polarized (CP) discrete lens antenna, which exhibits wide axial ratio and gain bandwidths. It consists of a transmitting surface (TS) and a linearly polarized feeding source. For the former, it is based on a dielectric unit cell (UC) which is composed of two parallel slabs. This UC is anisotropic in its cross-section and variable in its height, which provide two degrees of freedom to manipulate the phase difference and the phase shifts of two orthogonal electric field components, and thus the TS can seamlessly attain linear to circular polarization conversion and collimated beam. In the design of the TS, 3-bit phase quantization is adopted. Owing to the non-dispersive characteristic of the UCs, the proposed TS shows superior bandwidth performance over the existing studies. For the latter, it is a commercial wideband double-ridged horn antenna which matches with the TS in terms of bandwidth. As a proof of concept, a 9×9 prototype is fabricated by using 3-D printing technology. Experimental results show that the proposed antenna has a 3-dB axial ratio bandwidth (ARBW) of 44.2 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\%$</tex-math></inline-formula> (8.8-13.8 GHz). The 1-dB and 3-dB gain bandwidths are 16.5 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\%$</tex-math></inline-formula> (11.7-13.8 GHz) and 40 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\%$</tex-math></inline-formula> (9.2-13.8 GHz), respectively.

A new technique for designing the active microstrip antenna for circular polarization is presented. The circular polarization is achieved by four slits and a pair of truncated corner and the operating frequency is electronically controlled by the bias voltage of varactor diodes. Theoretical modal for an antenna is developed using modal expansion cavity model and circuit theory concept. The results are validated with MoM-based simulator and experimental results. A good agreement between the simulated, calculated, and experimental results is obtained. The tuning range is found to be 40.24% and shows about 71% reduction in antenna size as compare to the conventional circular polarized antenna.

A high‐gain, low‐cost empty substrate integrated waveguide (ESIW)‐fed circularly polarized (CP) antenna array is demonstrated for millimetre‐wave 5G applications in this letter. The ESIW is formed by metallized FR4 printed circuit boards. By stacking the metallic aluminium z‐shaped radiating slots atop the ESIW feeding network, CP radiation is achieved. The proposed 1 × 8 antenna array offers a high measured gain of 17.8 dBic and high measured radiation efficiency of 89.1%. The measured impedance bandwidth for |S11| ≤ −10 dB and measured axial ratio (AR) bandwidth for AR ≤ 3 of the proposed 1 × 8 array are 11.4% (36.5–40.9 GHz) and 7.8% (37–40 GHz), respectively.