Single-Fed Dual-Circularly Polarized Stacked Dielectric Resonator Antenna for K/Ka-Band UAV Satellite Communications

This paper presents a novel dual-band dual-sense circularly polarized slot antenna design. The dual-band is achieved using a single-layer bended microstrip-fed configuration coupled to two slots. The dual-sense circularly polarization is obtained by an asymmetric slot-ring and L-shaped microstrip-fed in a wide square slot. Simulated results show that the proposed antenna has good circular polarization characteristics for left-hand circularly polarization (LHCP) in the lower band and right-hand circularly polarization (RHCP) in the upper band. The 10dB return loss impedance bandwidths for the lower and upper band are 14.7% and 28.4% respectively. The 3-dB axial ratio (AR) bandwidths are 8.8% and 4.5% for the lower and upper band respectively.

This paper presents a novel dual-band, half E-shaped microstrip patch antenna (HEMSPA) with dual sense polarization. The proposed antenna covers two different frequency bands and radiates electromagnetic waves with left hand circular polarization (LHCP) and right hand circular polarization (RHCP) at lower and upper frequency bands, respectively. The dual frequency is realized by etching four T slits close to the radiating edges of HEMSPA. A shorting bar is adopted to attain LHCP waves at lower band while a vertical slot etched in the patch center aids in achieving RHCP waves at upper band. The proposed antenna has a small frequency ratio of 1.2 and good scalability. It can be easily re-designed for other operating frequencies with dual sense circular polarization (CP) or same sense CP at dual frequencies. The simulated reflection coefficient, axial ratio, and radiation pattern characteristics show a good agreement with the experimental data for dual-band performance. The measured −10 dB impedance bandwidth, 3 dB axial ratio bandwidth, and boresight gain are observed to be 1010 MHz, 70 MHz, 9.27 dBic and 120 MHz, 69 MHz, 6.63 dBic in the lower band, and upper band, respectively. The proposed antenna would be promising for modern wireless communication system applications.

This paper describes a monopole antenna with dual-band switchable circular polarization (CP) sense in WLAN and WiMAX bands. The proposed antenna consists of a rectangular patch fed by a microstrip line and a ground plane embedded with a T-shaped slot integrated with PIN diodes. The slotted ground is capable of exciting CP sense around 2.45 GHz for WLAN and around 3.4 GHz for WiMAX, respectively. Two triangular strips are added to improve impedance matching. The CP sense of the proposed antenna can be reconfigured between the right-handed circular polarization (RHCP) and left-handed circular polarization (LHCP) by switching the states of PIN diodes in the slot. The lower band 3-dB axial ratio (AR) bandwidth is 8.6%, and the upper band 3-dB AR bandwidth is 20.8%, in which the return loss is less than −10-dB. Simulated analysis and measured results are carried out and good agreement is achieved.

A new compact printed monopole antenna is presented in this paper. An open-loop hexagonal radiator excited by a microstrip feed line, which is printed on top of the substrate, which is FR4 type, while on another side, a partial ground plane is fixed and embedded with two pairs of slits as well as a pair of rectangular strips. Triple operating bands with two different polarization types are obtained. The lower band has right-hand circular polarization (RHCP) characteristic, whereas the upper band has left-hand circular polarization (LHCP) characteristic means that a dual-band dual-sense circular polarization (CP). Concerning the middle band, a linear polarization (LP) has been gotten in this antenna. Numerical analysis and experimental validation of the proposed antenna structure have been performed, and results are demonstrated. The measured impedance bandwidths (IBWs) are 14.7% (1.478-1.714 GHz), 6.8% (2.54-2.72 GHz), and 13.1% (4.29-4.89 GHz), respectively. The measured 3-dB axial ratio bandwidths (ARBWs) are 6.2% (1.510-1.606 GHz), and 22.7% (4.035-5.07 GHz) for the lower and the upper band, respectively. So, it's suitable for covering modern wireless applications such as GPS (Global Positioning System), LTE (Long Term Evaluation), and Satellite.

Reconfigurable antennas with polarization agility are critical for modern millimeter-wave (mm-wave) communication systems, enabling improved link reliability, interference mitigation, and system adaptability. This paper presents a dual-band, polarization-reconfigurable microstrip antenna based on a square patch notched at two opposite corners and loaded with four PIN diodes. A defected ground structure (DGS) is introduced to enhance circular polarization purity and extend bandwidth. The antenna operates over two frequency bands: 27–29 GHz (lower band) and 32–32.6 GHz (upper band). By appropriately biasing the PIN diodes, the antenna can generate either left-hand circular polarization (LHCP) or right-hand circular polarization (RHCP) in the lower band, while maintaining linear polarization in the upper band, providing multifunctional operation within a compact design. Simulated results confirm impedance matching in the 27–29 GHz band, with a 3 dB axial ratio bandwidth of 27.42–28.22 GHz and a minimum axial ratio of 0.2 dB near 28 GHz, indicating excellent polarization purity. The antenna achieves peak gain above 6.2 dBic in both circular polarizations at the lower band and 7.2 dBi in the upper band with linear polarization. Efficiencies reach 84% at 28 GHz and over 76% at 32.3 GHz. The antenna, feed network, defected ground structure, and biasing circuits are integrated in a three-layer PCB with sub-50 μm precision traces enabled by LPKF laser prototyping, ensuring minimal parasitics. Experimental measurements show good agreement with simulations. These results validate the proposed antenna as an efficient, compact, and versatile solution for polarization-reconfigurable mm-wave communication, with advantages in adaptability, integration, and performance stability.

In this communication, two wideband dual-polarized dielectric resonator antennas (DRAs) for X-band radar applications are presented. The design procedure is started with designing a linear polarized DRA fed by a microstrip line. The feedline is optimized to excite the hybrid electromagnetic (HEM) <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$_{11 \delta }$ </tex-math></inline-formula> modes of DRA which corresponds to magnetic monopole-like radiation. Then, a novel quadrature hybrid is designed in the feeding structure to provide both left-hand circular polarization (LHCP) and right-hand circular polarization (RHCP). Finally, two antenna prototypes are fabricated and tested: a dual (right hand and left hand) circular polarization DRA with omnidirectional pattern and an enhanced gain version of dual-polarized circular polarized (CP) DRA with a directive pattern. The measurement results of antennas confirm wideband impedance bandwidth (34% and 38.8%) as well as wideband axial ratio (AR) ones (23% and 30%) in element and array structures, respectively. The antennas also provide both RHCP and LHCP radiation. The first antenna contains monopole-like radiation which is aimed at wireless systems with omnidirectional pattern requirements. The second antenna, a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2\times 1$ </tex-math></inline-formula> antenna array, presents around 9 dB across the entire band. The presented antennas are good candidates for radar applications such as weather monitoring, air traffic control, and vehicle speed detection.

In this article, a low-profile high-efficiency dual-band 0.915/2.45 GHz circularly polarized (CP) antenna and its array are designed for radio frequency identification (RFID) reader applications. First, a dual-band antenna element is introduced to achieve dual-sense CP radiation using two pairs of crossed-dipoles for the first time. The right-hand CP (RHCP) wave at lower band is mainly produced by the first-order mode on longer dipole, while the left-hand CP (LHCP) wave at upper band is generated by the combination of first-order mode on shorter dipole and third-order mode on longer dipole. An artificial magnetic conductor (AMC) is used to improve the antenna directivity with low profile and makes this antenna easy to integrate into RFID system. Then, a rotated sequential phase feed CP array is proposed, fabricated, and measured. Measured impedance bandwidth (IBW) for <inline-formula> <tex-math notation="LaTeX">$\vert \text{S}_{11}\vert &lt; -10$ </tex-math></inline-formula> dB is more than 40.0&#x0025; at these two bands. Measured 3 dB axial ratio bandwidths (ARBWs) are 32.0&#x0025; (0.77&#x2013;1.06 GHz) and 27.8&#x0025; (2.22&#x2013;2.95 GHz). Compared with other dual-band CP reader antennas, which work in 0.915/2.45 GHz RFID systems, this new antenna array has a simpler configuration to achieve dual-band CP radiation. In addition, the 3 dB ARBWs are much wider than the previous antennas. Moreover, because the feeding network of this array is quite simple, the radiation efficiency is very high (&#x003E;90&#x0025;), and the peak gains are more than 9.0 and 15.0 dBic at corresponding bands.

Novel broadband monopole antenna designs with dual-band circular polarization (CP) are presented. The proposed antenna comprised of a ground plane embedded with an inverted-L slit, which is capable of generating a resonant mode for broadband impedance-bandwidth, and excites two orthogonal E vectors with equal amplitude and 90deg phase difference (PD) for radiating left-hand circular polarization (LHCP) at 2.5 GHz and right-hand circular polarization (RHCP) at 3.4 GHz. A bevel is cut in the rectangular radiator to increase the impedance-bandwidth. The measured result of the impedance-bandwidth is about 4.46 GHz from 2.12 to 6.58 GHz; the 3-dB axial ratio (AR) bandwidths are about 150 MHz at the lower band (2.5 GHz) and 230 MHz at the upper band (3.4 GHz). Furthermore, embedding an I-shaped slit in the rectangular radiator and adding an I-shaped stub in the ground plane, the impedance-bandwidth can be further increased to 6.30 GHz (2.17-8.47 GHz), and the 3-dB AR-bandwidth at the upper band is greatly enhanced from 230 to 900 MHz.

A novel and simple dual-band dual-sense circularly polarized (CP) metal-strip antenna is proposed. The antenna fed by a coplanar waveguide (CPW) with the advantages of uniplanar geometry and easier fabrication consists of a square slot and two split-ring elements. By appropriately introducing dual split-ring elements, the proposed dual-band CP design can easily be achieved. The two resonant frequencies are controlled by the size of the two split-ring elements. The proposed antenna prototype is fabricated and measured. Experimental results show that good CP radiation performances are obtained at both resonant frequencies. The proposed antenna has an impedance bandwidth (|S11 |≤− 10 dB) of 63.3% (2.0 ∼ 3.9 GHz), and the dual band circular polarization with left hand circular polarization (LHCP) at 2.2 GHz and the right hand circular polarization (RHCP) at 3.8 GHz are obtained. Also, the 3-dB axial ratio bandwidths are about 220 and 190 MHz at the lower and upper band, respectively.

In this article, a wideband dual-feed, dual-sense circularly polarized (CP) dielectric resonator antenna (DRA) is proposed and demonstrated. An L-shaped slot and a vertical metal strip, fed by the same microstrip line, simultaneously excite the antenna. Using this feeding method, a dual-band, dual-sense CP triangular DRA is obtained by employing the DRA mode excited at the lower band and the hybrid mode excited at the upper band. Building on this initial design, a rotationally symmetric bowtie DRA (bDRA) consisting of two triangular dielectrics is proposed for wideband dual-sense CP operation. An additional excited slot mode widens impedance bandwidth and broadens the axial-ratio bandwidth (ARBW) of the lower band. Meanwhile, a higher order DRA mode excitation widens the ARBW of the higher band. The characteristics of these two DRAs are explored via simulation. Moreover, a bDRA prototype is fabricated and measured. The results demonstrate a directional antenna with a wide 10 dB return loss bandwidth of 63.7%, a broad 3 dB ARBW of 27.1% for the left-hand circular polarization, and a broad 3 dB ARBW of 12.8% for the right-hand circular polarization.

3-D printed dual-band, dual-sense circularly polarized dielectric resonator antenna with a bandstop filtering response using planar via-free D-CRLH feeding network

For the application of ambient electromagnetic energy harvesting, it is important to collect as much electromagnetic energy as possible in broadband and with arbitrary polarizations. Meanwhile, the antenna should also have high receiving efficiency in order to effectively convert the collected energy into radio frequency current. To meet this requirement, a novel broadband dual circularly polarized (CP) dielectric resonator antenna (DRA) with high receiving efficiency is proposed. The characteristic mode analysis (CMA) is applied to analyze the proposed DRA to reveal the intrinsic behavior of the DR, so that proper mode excitations can be guided. It is found that broadband CP radiation is achieved by exciting two pairs of orthogonal degeneration modes. By choosing a broadband feeding structure, a broadband DRA can be obtained. When different ports are excited, left-hand CP (LHCP) or right-hand CP (RHCP) field can be generated. Measurements show that the antenna has a 3 dB axial-ratio (AR) bandwidth of 43.5%. The impedance bandwidth is wide enough to cover the whole AR bandwidth. The receiving efficiency of the proposed antenna is about 85% within most of the operating frequency range. With these appealing features, the proposed DRA is an excellent candidate for ambient electromagnetic energy harvesting.

A novel design of a dual-band and dual-sense circularly polarized coplanar-waveguide-fed monopole antenna with two rectangular parasitic elements and an I-shape grounded stub is presented here. The monopole consists of a vertical and a horizontal section. Lower band is obtained due to 90° phase difference between currents in the two orthogonal branches of the monopole. Upper band is obtained due to the I-shape stub. Parasitic elements help in input impedance matching. The dual-band and dual-sense antenna provides wide 10-dB impedance bandwidth of 71.63% at 2.82 GHz. The 3-dB axial-ratio bandwidths are 27.45% at 2.55 GHz (right-hand circular polarization) and 7.1% at 3.53 GHz (left-hand circular polarization).

The two shorted rectangular-ring slots antenna fed by a microstrip line is presented to achieve the novel characteristic of wide impedance bandwidth with the opposite sense circular polarizations (CP). If the two rectangular-ring slots are arranged to be shorted in the opposite direction, reversely circular polarization will be obtained in the different frequency band. A microstrip line is used to feed power and to couple to the two shorted rectangular-ring slots. Meanwhile, the impedance and axial-ratio (AR) matching are done by adjusting line's parameters. An antenna example is given to result in the lower and upper bands in the 1575 MHz and 1.8 GHz bands. The measured impedance bandwidth is 27.54% which covers the 1575 MHz and 1.8 GHz band. But the polarization for the lower and upper bands is right- and left-hand CP, respectively. The frequency ratio of opposite sense CP band can be lowered to 1.13 and then, give a good choice to design the low frequency ratio with opposite sense CP. The measured AR's center frequency and bandwidth for the lower band is 1.602 GHz and 2.81% respectively, and the minimum AR and antenna gain is 0.987 dB and 3.8 dBic for RHCP, respectively. Meanwhile, the AR's center frequency, bandwidth, antenna gain for the upper band are 1.820 GHz, 3.24%, and 2.43 dBic for LHCP, respectively. Radiation patterns in both bands are broadside radiations and similar to each other except the opposite sense CP characteristic.

In the present article, a novel single fed square dielectric resonator antenna (SDRA) is presented and two orthogonal modes ( TE 111 x and TE 111 y ) of SDRA are utilized to produce the wideband circular polarization. To generate circular polarization over a broad frequency band, a new technique known as hybrid DRA has been proposed in this article. In this technique, the feeding circuit act as a radiator and also provides feeding to the dielectric resonator which enhances the impedance and axial ratio bandwidth. A 3-dB axial ratio bandwidth of 26.66% is achieved by the SDRA excited through a rectangular patch united with 50 Ω microstrip line. In order to further increase the axial ratio bandwidth from 26.66% to 48%, a notch is truncated from the rectangular patch. The design antenna prototype has been fabricated and experimentally tested. Experimental results illustrate that the proposed structure has broad impedance and axial ratio bandwidth of 75.86% and 43.75%, respectively, and the entire axial ratio bandwidth fully matched with the impedance bandwidth. The proposed antenna produces a right handed circularly polarized (RHCP) field. By taking the mirror image of the proposed microstrip feeding, the RHCP field is converted into left handed circularly polarized (LHCP) field. This antenna is preferred for wireless applications such as indoors communication, remote sensing, wireless sensor systems and WLAN/WiMAX applications.