Compact Feeding Network Research Articles

Wideband microstrip antenna operating in TM01 mode and its array with compact feed network

AbstractThis letter presents a broadband linearly polarized (LP) microstrip antenna operating in TM01 mode and its 2 × 2 array with a compact network. Different from the TM10 mode, the TM01 mode can be used to design arrays without a bending feed network. The impedance bandwidth (IBW) of the proposed antenna is 9.6% (2.19 GHz–2.41 GHz). Subsequently, the characteristic of this antenna operating in TM01 mode is employed to design a 2 × 2 planar array. The measured results show that the array has an IBW of 9.5%, a maximum gain of 11.4 dBi with low cross‐polarization.

Ka-Band Huygens Antenna Array With Very High Aperture Efficiency and Low Sidelobes

A Ka-band Huygens antenna array with extremely high aperture efficiency (AE) and low sidelobe levels is reported for 5G millimeter-wave (mm-wave) wireless applications. The basic array element is an innovative Huygens subarray consisting of two open rectangular waveguides that form an aperture consisting of a 1 <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> 2 set of orthogonal, tightly coupled electric and magnetic elements separated by a virtual gap that are balanced, in- phase, and radiate Huygens cardioid patterns. A larger 8 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times16$ </tex-math></inline-formula> element array is then realized with 64 of these 1 <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> 2 subarrays. With excitations of equal amplitude, the full broadside-radiating array achieves an AE up to 97.5% in the operating bandwidth, which is very close to the 100% limit associated with an ideal uniform aperture distribution. Moreover, a highly efficient and compact feed network with tapered-amplitude and in- phase excitations from the array center to its edges is designed to achieve sidelobe and backlobe levels less than −20 dB. The −10 dB impedance bandwidth covers 26.7–29.65 GHz, and the peak realized AE (RAE) reaches 82%. A full-aluminum array prototype was fabricated with standard machining processes and tested. The measured performance characteristics agree well with their simulated values, confirming the efficacy of their designs.

Designing and Modeling of a Dual-Band High-Efficiency Rectenna Using Dielectric Resonant Antenna Array

In this paper, we proposed a high-efficiency 2.45 GHz and 5.8 GHz dual-band rectenna for wireless energy harvesting (WEH). First, a dual-band dielectric resonant antenna (DRA) was designed. A 4-element DRA array was further developed using a compact feeding network. The measured gains of the DRA array were 5.5 dBi at 2.45 GHz and 12.9 dBi at 5.8 GHz. Then, a new type of impedance regulation stub (IRS) was introduced that significantly improved the conversion efficiency of the rectenna. The result showed that the conversion efficiency of the rectifier was 66% and 62% at 2.45 GHz and 5.8 GHz, respectively, when the input power level was 10 dBm. Furthermore, the proposed rectenna was validated to activate a standard BQ25504 DC-to-DC boost converter and charge a supercapacitor. The results demonstrated that the proposed rectenna could be an appropriate solution for WEH applications.

Hybrid Waveguide Feed Network for Aperiodic Subarray Beamforming

In this letter, a hybrid waveguide feed network for an aperiodic subarray beamforming antenna is presented. The feed structure is divided into vertical and horizontal parts. Vertical parts have inclined slots with a reduced-height waveguide, and the horizontal part has unequal <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">H</i> -plane septum power dividers to achieve a compact feed network with acceptable electrical characteristics. The angle of each inclined slot and the position of each septum were designed for amplitude weighting and in-phase characteristics. For comparison, a simple resonant feed network without septum power dividers (i.e., with waveguides and inclined slots) was simulated to access the effectiveness of the proposed network. The proposed structure was fabricated using computer numerical control milling and diffusion bonding. The input reflection coefficient was less than −15 dB, and the transmission phase difference between 20 ports was less than 72° within a bandwidth of 2.4%. This feed network design has potential applications in electronically scanned arrays and subarray antennas for a limited field of view.

A Novel High-Gain Sum and Difference Conical Beam-Scanning Reflector Antenna

A novel sum and difference (SD) conical beam-scanning reflector antenna is proposed in this paper. The reflector surface, illuminated by two omnidirectional horns, is a body of revolution obtained by revolving the generating parabola about a symmetry axis. The horns stacked along the symmetry axis of the reflector are fed by a nest coaxial waveguide. Teflon lens is used to improve the side lobe levels and reflection coefficients of the feed horns. By tilting the generating parabola and using the offset feeding method, two conical beams, with different beam pointing angles, were generated. A compact feed network was also designed to feed the two horns, which includes two rectangular TE10 mode-to-coaxial TEM mode transitions and a Magic-T to implement SD beams. The scanning performance of conical beams can be achieved by mechanically moving the feed antennas along the symmetry axis and taking full advantage of offset focus characteristic of the parabolic reflector. The error in angle measurement was also discussed. The SD conical beam-scanning antenna was formed by a parabolic dish with a radius of 18 λ operating at 24 GHz. The proposed antenna was designed, simulated, and fabricated. The measured results show that the difference beam null-depth is -25 dB and the sum beam gain is 15 dBi at 40°. The sum beam gain varies by less than 1.5 dB across the scan coverage from 30.8° to 45.2°. The measured results are found to be in good agreement with the simulated ones.

Low Gain Ripple and DC-Grounded Slant-Polarized Formulation With 360° Broadbeam Coverage

In this paper, a new slant-polarized slot antenna configuration is presented for direction finding and base station applications. The proposed antenna comprises enhanced size coaxial cables, slots, and feeding assemblies. The slant polarization is achieved by four angled slots etched around the outer cylinder of the oversized coaxial cable. An internal compact axis-symmetric feeding network connects primary apertures to form the omnidirectional antenna. Simulations and measurements demonstrate that the antenna maintains an omnidirectional pattern from 2.5 GHz to 2.8 GHz, having 11.3% bandwidth (measured return loss <−10 dB) and gain ripple of ±0.2 dB in the azimuth plane, which leads to the stable operational coverage. Another benefit of this structure is its polarization purity. The cross-polarization levels are below −14dB over the whole bandwidth. Move over; it is ruggedized DC short, self-supporting, and surface-mountable structure. Furthermore, compact and conformal shape reduces aerodynamic drag and makes this antenna a potential candidate for mounting vehicle systems too.

A Wideband Circularly Polarized Array Antenna With Compact and High-Efficiency Feeding Network

A wideband circularly polarized (CP) waveguide array antenna is proposed in this article. The proposed array antenna consists of four antipodally ridged elements and a compact feeding network with two orthogonal septa inserted to a stepped cavity. Both the components are wideband and they can work independently or together. The proposed topology gives a good solution to feed a $2 \times 2$ waveguide subarray which is the basis of large-scale arrays. It exhibits a larger working bandwidth than the array antennas fed by high-order mode cavities. A prototype is fabricated using 3-D printing and milling technologies. Measured results demonstrate a bandwidth of 40.3% from 9.9 to 14.9 GHz, in terms of the reflection coefficients less than −15 dB and the axial ratios smaller than 3 dB. An expanded $8 \times 8$ CP array antenna is explored based on the proposed $2 \times 2$ subarray to show the potentials of our design, and a total efficiency over 78% within a bandwidth of 38.7% is obtained by simulation.

A compact feeding network with radiation contribution for X‐band marine radar antenna array applications

AbstractA compact feeding network with radiation contribution is proposed in designing microstrip patch array antenna (MPAA) for X‐band marine radar applications. The 1‐to‐4 feeding network consists of two circular‐sector patch balun, which can radiate electromagnetic wave with the same polarization of the patch array for enhancing the gain and suppressing the cross polarization. The feeding line in the series‐fed patch subarray is modified as the step‐impedance microstrip line to decrease the side‐lobe level (SLL). To verify the method, a 28‐element 9.41‐GHz MPAA with the proposed radiated feeding network is designed and fabricated. Measured results show that the impedance bandwidth is 183 MHz with a peak gain of 21.3 dBi. The SLL is 27.8 and 21.4 dB in the E‐ and H‐planes, respectively. The cross polarization is effectively reduced, which is lower than the copolarization of about 57 dB.

Broadband Polarization-Reconfigurable Slot Antenna and Array With Compact Feed Network

A broadband polarization-reconfigurable slot antenna and 2 × 2 array with compact feed network are proposed in this letter. The wide circle slot, etched on the ground, serves as the radiation aperture with a wideband characteristic. A novel compact microstrip (MS)–slot line–coplanar waveguide feed network on the top side is proposed to realize reconfigurable-polarization senses. Three p-i-n diodes are loaded on the MS for generating the linear polarization (LP), left- and right-hand circular polarizations (CPs) in the wide circular slot. Based on the compact feed network, a 2 × 2 polarization-reconfigurable antenna array with two dielectric layers is suggested. The feed networks are printed on the bottom and top metal planes, while the wide slots are on the middle one. To further improve the directivity, a reflector is loaded at the back of the array. A prototype operating at S -band is fabricated and measured. The measured 10 dB impedance bandwidth is 10.8% for the LP operation. The overlapped 10 dB impedance and 3 dB axial-ratio bandwidths are 14.5% for the CP operations. The peak gain reaches 14.7 dBi, which comes from the low loss and compactness of the novel feed network. The design can be extended to a larger array without increasing the structure complexity.

A Compact Planar Omnidirectional MIMO Array Antenna With Pattern Phase Diversity Using Folded Dipole Element

This paper presents a planar omnidirectional multiple-input multiple-output (MIMO) antenna with pattern phase diversity. The profiles of conventional dual-polarized omnidirectional MIMO antennas are too high to be planar integrated due to the limited bandwidth of vertical-polarized element. Therefore, a dual-channel horizontal-polarized MIMO antenna is proposed for the planar integration of omnidirectional MIMO antenna. The antenna is formed with four-element folded dipole array, and a compact feed network with two sets of 90° progressive phases is employed to feed the two channels with shared elements, thus the antenna can be integrated into a sheet of substrate with an ultralow profile of 0.8 mm. Although the polarization and radiation pattern (amplitude) of the two colocated channels are the same with each other, a high isolation is still achieved as a result of the orthogonal pattern phase. A prototype was fabricated to validate the performance. The measured highest isolation between two channels is 31.7 dB, and −10 dB isolated bandwidth is 2.29–2.57 GHz (11.7%) with S11 < −14 dB and envelope correlation coefficient less than 0.05, which shows a good diversity performance. Therefore, the proposed dual-channel antenna gives a feasible solution for the planar integration of the omnidirectional MIMO system.

Wideband Dual-Mode Patch Antenna With Compact CPW Feeding Network for Pattern Diversity Application

A wideband microstrip patch antenna is proposed in this communication for pattern diversity application. Broadside and omnidirectional radiation patterns are generated by the odd and even modes of a single circular patch. A compact feeding network based on coplanar waveguide is designed to provide in-phase and out-of-phase excitations, which can excite the two modes in wide bandwidth. The size of the feeding network is only $35 \times 14.5$ mm2. A prototype of the proposed antenna is fabricated and tested. The measured overlapped bandwidth ( $\vert \text{S}_{11}\vert dB and $\vert \text{S}_{22}\vert dB) achieves 775 MHz (2.165–2.94 GHz) or 31% corresponding to the center frequency. The Port isolation is below −28 dB in the entire bandwidth.

Low‐profile circularly polarised patch–ring antenna with compact feeding network

This study presents a low-profile circularly polarised microstrip antenna with two radiators composed of a corner-truncated patch and a corner-truncated ring. They are stacked and printed on the two sides of a suspended FR4 substrate. The axial ratio (AR) bandwidth of the proposed design is greatly improved compared with the traditional patch by merging the existing bandwidth of the patch with the additional bandwidth of the ring. Parametric analysis indicates that the modes of the patch and the ring can be tuned independently. A λ /4 microstrip line is meandered in the inner part of the ring to reduce the size of the feeding network. The antenna profile is only 0.065 λ . A prototype of the proposed antenna is built and tested. The simulated and measured results agree well. The measured 10 dB return-loss bandwidth is 20.6% (2.375-2.88 GHz) and the 3 dB AR bandwidth is 6.94% (2.39-2.56 GHz). The measured gain is ~7 dBiC in the concerned bandwidth, with a variation of 1 dB.

A Compact Dual-Band Circularly Polarized Antenna with Wide HPBWs for CNSS Applications

A compact dual-band circularly polarized antenna with wide half-power beamwidths (HPBWs) for compass navigation satellite system applications is proposed in this paper. The CP radiation is realized by arranging four compact dual-band inverted-F monopoles symmetrically to the center point, where the four monopoles are excited with a 90° phase offset through a compact sequential-phase feeding network. The compactness of the dual-band inverted-F monopole is realized by inserting two chip inductors in the horizontal portion of the monopole. The overall dimension of the antenna is only 0.211λ0 × 0.211λ0 × 0.057λ0, where λ0 is the corresponding free-space wavelength at 1.268 GHz. Experimental results show that the proposed antenna exhibits two overlapped impedance and axial ratio bandwidths of 50 MHz (1.236–1.286 GHz) and 40 MHz (1.532–1.572 GHz). Wide HPBWs of about 120°/125° and 121°/116° (XOZ/YOZ planes) at center frequencies (1.268, 1.561 GHz) of the CNSS-2 B3 and B1 bands are obtained, respectively. With these good performances, the antenna can be a good candidate for CNSS applications.

An Embedded Lightweight Folded Printed Quadrifilar Helix Antenna: UAV telemetry and remote control systems

An embedded folded, printed, quadrifilar helix antenna (FPQHA) with a wide-angle coverage for unmanned aerial vehicles (UAVs) telemetry and remote control systems is presented in this article. The novelty of this design is that the FPQHA needs to be designed carefully due to UAV tail dimensions and weight constraints while maintaining a high performance to be integrated in the inner part of the UAV tail fuselage to reduce aerodynamic drag. The radiating terminal, formed by a folded, printed, four-helix, radiating section and a compact feeding network, is designed to provide left-handed, circular polarization (LHCP). The complete design offers a very homogeneous pattern in azimuth with a very good axial-ratio (AR) level over a wide range of elevation angles. The use of low-loss and lightweight materials is also an advantage of this design. The wide radiation pattern favors its use for multielement communication systems. Finally, the antenna performance results are obtained mounted inside a UAV tail platform.

Compact UHF Three-Element Sequential Rotation Array Antenna for Satcom Applications

This paper proposes a miniaturized UHF antenna with three sequentially rotated elements operating at 433 MHz for Satcom applications. Like most of its former counterparts, the antenna consists of a main body with three radiation elements driven by a feeding network. To evaluate the matching characteristics of the main body, a united reflection coefficient for the three elements, taking into consideration the coupling between them, is derived. The main body is formed by three sequentially rotationally arranged bent planar inverted-F antenna elements, which helps dramatically reduce the size of the antenna. To drive the main body, a new compact feeding network based on spiral-shaped Wilkinson power divider is also developed, achieving three-way power splitting and 120° phase shifting. It has the merits of compact planar structure, equal power splitting, and high isolation between output ports. In this way, a sequential rotation array antenna with compact size (Ø0.216λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> ), low cost, easy fabrication, and good performance is realized. A prototype is fabricated and measured, and the results prove the good performance of the proposed design.

Compact Sequential Feeding Network Using Two-Double-Sided Couplers with Quadruple Output Ports

A compact broadband sequential feeding network designed for a wideband circular antenna is simulated and fabricated, where the 50-Ω input is equally divided into four 50-Ω outputs with equal amplitude and 90° successive shifts. This series-type feed network just composes of two double-sided couplers which have been further reduced to a great degree by meandering the microstrips. The measured 10-dB impedance bandwidth is 39% from 1.71 to 2.54 GHz, and the phase difference between two arbitrary adjacent ports is 90° ± 4.7° over the 1.75–2.35 GHz range. Note that the measurements agree reasonably well with the simulations.

Wide‐beam spiral antenna with three folded arms fed by compact three‐way Wilkinson power divider

A compact planar antenna is proposed for wide-beam applications with circular polarisation. The antenna has three multi-folded spiral arms fed by equal signals with 120° out of phase with respect to each other to produce a symmetrical radiation pattern. A compact feed network with a Wilkinson power divider is also designed to produce the required 120° phase difference for the inputs of antenna.

Patch array antenna with cavity‐backed SIW feed for X‐band applications

ABSTRACTIn this article, a new arrangement of patch array antenna incorporated with cavity back substrate integrated waveguide (SIW) and stacked structure is which operating at X‐band, is presented. The proposed structure enhances the gain and bandwidth of the array antenna markedly. The prototype antenna contains a 2 × 2 patch array formation with compact feed network that helps to miniaturize the structure and improve radiation properties in antenna. The inner metallic posts inside of the antenna limit the propagation of the lower mode and therefore TM220 mode is propagated as a dominant mode. For designing of the antenna, equivalent cavity model is used, but for the final full wave simulations, it is replaced with SIW configuration. The stack layer is added to the antenna to improve its bandwidth, efficiency, and gain. The proposed antenna is fabricated on RO4003 substrate with thickness of about 0.8 mm, and total dimensions of 38 × 38 mm2 and stacked layers are etched on RT‐Duroid 5880 substrate with thickness of 1.6 mm. An acceptable agreement is obtained between measured and simulated results. The proposed antenna has 2.7% bandwidth and at the center frequency (9.01 GHz) its gain is 10.8 dBi with 95% efficiency and 25.02 dB front to back ratio. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:319–323, 2016

Multi-band conical and inverted conical printed quadrifilar helical antennas with compact feed networks

Comparison between radiation patterns of quadrifilar helical antennas with three shapes of cylindrical, conical and inverted conical is provided in this paper. Multi-folded printed lines are used as the arms of quadrifilar helical antennas and the heights of them with their supports are fixed at 35cm to make a valid comparison. These antennas have multiple resonance frequencies and they can be used for multiband applications. Radiation patterns of the three shapes are compared at three resonance frequencies, 435MHz, 620MHz and 755MHz. It is indicated that the conical antenna has a wider beam-width and the inverted conical antenna has higher gain at broadside. In addition, three compact feed networks based on miniaturized single layer Wilkinson power dividers for three frequency bands of the antennas are designed and their parameters are reported. Furthermore, the conical antenna and the feed networks are fabricated and simulation results are validated by the measurement results.

A programmable compact wide-band RF feed network

The design and fabrication of a wide-band programmable radio frequency (RF) feed network is proposed. It is designed to cover a wide band from 2.5 to 6 GHz over two separate branches. The feed network is simulated and fabricated on an FR-4 substrate with 0.8 mm thickness. Good matching between simulation and measurement results is achieved. The measured amplitude resolution was 0.5 dB with a maximum error of 0.22 dB. The measured phase resolution was approximately 5.6° with 1° maximum error. This design is a generic one that can be used in any kind of RF or antenna systems.