Search

A $V$ -band substrate integrated coaxial line (SICL) to rectangular waveguide (RWG) transition is proposed in this letter. In this design, a folded dipole is used to achieve a more compact structure and better impedance matching in the operating band. Compared with other transitions based on single-layer substrates, this design is more suitable for mixed multilayer circuits. For verification, a back-to-back transition prototype is fabricated by standard multilayer printed circuit boards processing and measured. The measured results show that the proposed transition has a wide −10-dB impedance bandwidth of 40% (from 50 to 75 GHz), and an insertion loss of lower than 4 dB over the operating bandwidth. Owing to compact size and wide operating bandwidth, the proposed transition is valuable to advanced millimeter-wave (mmW) circuit systems. [ABSTRACT FROM AUTHOR]

This letter presents a planar mode composite folded substrate integrated waveguide (MCFSIW) that enables simultaneous propagation of the TE10 and folded TE10 (FTE10) modes. By adjusting the gap width of the MCFSIW, the cutoff frequency of the FTE10 mode can be tuned to be the same as that of the TE10 mode. The operation principle and propagation properties of the MCFSIW are analyzed. To excite the two modes independently, a simple joint feeding network (JFN) with a wide bandwidth and a high isolation is designed. A prototype of the MCFSIW with JFNs is fabricated and measured, and the measured results agree well with the simulations. The proposed MCFSIW is attractive in the development of multifunction and parallel data transmission systems. [ABSTRACT FROM AUTHOR]

In this article, a spoof surface plasmon (SSP) ring resonator to generate dynamically reconfigurable vortex beams is proposed. According to the phase constant control of the SSP and the harmonic radiation principle, the tunable cylindrical vector vortex beams (VVBs) with different topological charges can be obtained. The tunable system that operates by electronic control would utilize varactors to change the wavenumber of SPP on the ring resonator and realize the reconfigurable VVBs modes at a fixed frequency. All VVBs have excellent orbital angular momentum (OAM) purity (above 90%). Interestingly, the antenna also simultaneously radiates the scalar vortex beams with tunable OAM modes. Both numerical simulations and experimental characterizations confirm the theoretical predictions. Because the designed antenna has the advantages of simple feeding network, easy bias circuit, as well as miniaturization and integration compatibility, we anticipate that the antenna will enable a wide range of applications for future wireless communication and imaging technologies. [ABSTRACT FROM AUTHOR]

A novel cascaded dispersive delay structure based on a periodic glide symmetric stub-loaded microstrip transmission line is presented. Two group delay peaks are superposed to realize a group delay response that illustrates linear characteristics versus frequency. Two examples with slopes 0.83 and 2 ns/GHz, respectively, are proposed. Verified by experiments, the simulated and measured group delays show a well agreement. [ABSTRACT FROM AUTHOR]

This letter presents a novel class of single-layer substrate-integrated waveguide (SIW) inline filters with flexible transmission zeros (TZs). The basic structure is an oversized half-mode SIW (HMSIW) rectangular cavity (RC) perturbed by a pair of metallic via-holes or an open-ended slotline. Each perturbed HMSIW RC can provide one pole and two TZs. By changing the distance between the perturbation via-holes or the length of the perturbation slotline, one TZ can be moved either above or below the passband, while the other is always located above the passband. Based on these perturbed HMSIW RCs, two SIW three-pole inline filters are fabricated and measured to validate the design concept. [ABSTRACT FROM AUTHOR]

The design and implementation of a wideband circularly polarized folded reflectarray antenna (CPFRA) with a linearly polarized (LP) feed antenna is presented in this letter. The subreflector of the proposed CPFRA is in the form of a polarization-sensitive frequency selective surface (FSS) based on the antenna-filter-antenna (AFA) technology other than the traditional polarizing grid. The AFA FSS is designed to convert the LP incident wave into circularly polarized (CP) wave within its passband and reflect the orthogonal LP incident wave over a wide frequency band. Futhermore, the sequential rotation technique is applied in the design of main reflectarray and subreflector to greatly enhance the axial ratio (AR) bandwidth of the CPFRA. An antenna prototype has been fabricated and measured at X-band. Good agreement between the measured and simulated results has been achieved by the wideband CPFRA. The measured results show that the maximum antenna gain reaches up to 28.2 dBic at 10.2 GHz with its aperture efficiency of 43.3%. The 3 dB gain frequency band is from 9.1 to 10.6 GHz and the 3 dB AR frequency band from 8.7 to 11.2 GHz, respectively. [ABSTRACT FROM AUTHOR]

In this letter, a novel dual-band coupler made of only three coupled microstrip–slotline (CMSL) sections is proposed to achieve a tight coupling with a high band ratio in a small size. A desired dual-band operation can be obtained by proper design of the coupling levels of the CMSL sections. Explicit design equations of the proposed coupler were derived by the method of even- and odd-mode excitations, and the characteristics of the CMSL were studied. For demonstration, a 3-dB dual-band CMSL coupler operating at 1 and 3 GHz is designed, fabricated, and measured. The proposed coupler has the advantages of small size, tight coupling, and high isolation. [ABSTRACT FROM AUTHOR]

This letter presents a wideband sequential-rotated (SR) circularly polarized (CP) 2 × 2 filtenna array with multiple radiation nulls for high out-of-band rejection level. A pair of arc-shaped via walls is introduced to split the degenerate modes TE120/TE210 of the substrate integrated waveguide (SIW) cavity for achieving CP characteristics. SIW cavity modes TE110 and TE220 are generated at the lower and upper band edges, respectively, to form a bandpass filtering response. A CP patch is embedded to enhance the AR bandwidth and create an additional radiation null near the upper band edge. Four filtering slots are further introduced around the radiation aperture to create another radiation null in the upper stopband. This compact filtenna element can achieve high stopband rejection without external filtering circuits. A SR feed network is designed for 2 × 2 array implementation with enhanced gain and AR bandwidth. By integrating a simple filtering structure in the SR feed network, the out-of-band rejection level in the lower stopband can be significantly improved. For demonstration, a 2 × 2 SR filtenna array was fabricated and tested. Good agreements between the measured and simulated results are observed, with a wide AR bandwidth of 18% (centered at 10 GHz), a peak gain of 13.2 dBic, and out-of-band rejection levels of 33 dB and 23 dB in the lower and upper stopbands, respectively. [ABSTRACT FROM AUTHOR]

In this letter, a planar endfire filtering antenna with a controllable passband and a high gain based on spoof surface plasmon polaritons (SSPPs) is proposed. Its radiating part consists of three pairs of sector-shaped patches and I-shaped directors which are linked with the end of SSPPs feeding line. As demonstrated, the filtering performance of the proposed antenna can be easily adjusted by changing the size of all the branches with metal vias, round-shaped, and π-shaped resonators. A prototype operating in 8–9 GHz is fabricated and tested to verify the design, which reveals an average gain of 8.6 dBi, an out-of-band suppression level of more than 12 dB, and a profile of 0.014–λ0. Good agreement is achieved between the simulated and measured results. Simple and controllable design methods and good performance indicate its significance in modern communication systems. [ABSTRACT FROM AUTHOR]

In this letter, a compact bandpass filtering power divider with tunable bandwidth based on spoof surface plasmon polaritons (SSPPs) and substrate integrated waveguide (SIW) is proposed. The hybrid-SIW-SSPP structure shows good potential to expand the scope of bandwidth control of the device. The bandwidth can be designed in a wide range by simply optimizing its dimensions or loading interdigital structures (ISs). Defected ground structure (DGS) is also introduced on the bottom layer to further improve the out-of-band suppression. And good isolation can be obtained via additional resistors welded across the SSPP slot. A prototype loaded with dumbbell-shape DGS and two resistors is fabricated with an overall size of 45 mm $\times18$ mm $\times0.5$ mm. Both $S_{21}$ and $S_{31}$ are around −3.8 dB within the whole $X$ -band. The simulated and measured results agree with each other well. [ABSTRACT FROM AUTHOR]

A low radar cross-section (RCS) slot array antenna based on absorptive frequency-selective structure (AFSS) is presented in this letter. The AFSS unit cell is constructed by two lossy layers and four double-sided parallel strip lines (DSPSLs). The radiation performance of the antenna can be preserved due to the transmission window of the lossy layers. Wide absorption bands of the AFSS are achieved due to periodic impedance of the DSPSL and the combination of the lossy layers. The operating principle of the design is demonstrated, and a prototype is fabricated and measured to validate the design. The proposed design features both wide RCS reduction band of the antenna and wide transmission band of the AFSS. [ABSTRACT FROM AUTHOR]

This communication proposes a shared-aperture self-diplexing antenna using the composite parallel-plate waveguide (PPW). The long-straight slots (LSSs) etched on the top surface of the PPW are utilized as the common radiation aperture for two operating bands. At the high frequency band, the proposed antenna, excited by the alternative-phase TE10-mode wave, operates as a leaky-wave antenna (LWA). Meanwhile, it serves as a continuous transverse stub (CTS) array antenna when excited by the TEM wave at the low-frequency band. Two kinds of feeding networks are adopted to generate the alternative-phase TE10-mode wave and TEM wave, respectively. To verify the proposed method, a millimeter-wave prototype is designed, fabricated, and measured. The measured results show that −10 dB fractional bandwidths (FBWs) are 3.42% (76.25–78.9 GHz) and 14.5% (83.2–96.2 GHz), respectively, and the port isolation is higher than 40 dB. Additionally, the peak gains are 27.1 dBi at 78.5 GHz and 25.3 dBi at 90 GHz, respectively. The proposed antenna can be used to develop compact frequency-division system without using duplexers and multiband wireless systems. [ABSTRACT FROM AUTHOR]

A dual-polarized lower band (LB) antenna element is proposed in this letter. A pair of vertical arms and a pair of horizontal arms are designed with two cross Γ-shaped feeding lines together for ±45° polarizations. The sleeve arm can suppress the scattering for high-frequency electromagnetic wave and have almost negligible effect on low frequency. Meanwhile, unobstructed space for placing the higher band (HB) elements is reserved with surrounded scheme. The dual-band antenna (DBA) with four HB elements operating from 1.46–2.43 GHz and one LB element operating from 0.65–1.11 GHz is designed and fabricated. The simulated and measured results show that the stable radiation performance and low mutual interference for LB and HB elements are achieved in DBA. [ABSTRACT FROM AUTHOR]

A gain-enhanced antenna consisting of a bandpass frequency selective surface (FSS) and a patch antenna is initially proposed in this communication. By utilizing the reflection characteristic of the FSS, a quasi-Fabry–Perot (F-P) cavity is formed between the FSS and antenna’s ground, which considerably improves the gain of the antenna. Meanwhile, the bandpass FSS has a little phase compensation for oblique transmitting waves, which also slightly enhances the gain. Then a low-radar cross section (RCS) and gain-enhanced antenna is proposed by using absorptive/transmissive frequency selective structure (ATFSS). It is implemented by mounting the ATFSS above a patch antenna. The ATFSS is constructed by stacking a lossy layer above a bandpass FSS. Both antennas are fabricated, assembled, and measured. They achieve a gain-enhancement of 5.27 and 3.84 dB, respectively. Besides, the low-RCS antenna achieves 10 dB monostatic RCS reduction from 5 to 5.33 GHz and from 9 to 13.4 GHz under the TE-polarization, and from 8.4 to 13.5 GHz under the TM-polarization, respectively. Simulated results show it also achieves a good improvement in bistatic RCS reduction as well. [ABSTRACT FROM AUTHOR]

A planar dual-band shared-aperture array antenna for the ${K}$ -/Ka-band low Earth orbit (LEO) satellite communication is presented in this article. Substrate integrated coaxial line (SICL)-fed bow-tie transverse slots and substrate integrated waveguide (SIW)-fed slot pairs are employed to provide ${K}$ -band horizontal polarization and Ka-band vertical polarization, respectively. The ${K}$ -band and Ka-band radiating elements share a common metallic-via-array, which can effectively improve the port-to-port isolation. Furthermore, the port-to-port isolations in both bands can be also improved by introducing the high-pass characteristic of SIW and out-of-phase cancellation between two current paths. For the sake of achieving low-profile height and compact size, the ${K}$ -band feeding network is subtly buried between Ka-band shielding cavities. As a proof-of-concept example, a shared-aperture dual-polarized array antenna operating at ${K}$ -/Ka-band is designed and fabricated for verification by using a multilayer printed circuit board (PCB) technology. The measured results show a good concordance with the simulated one, indicating that the proposed antenna has the advantages of wideband, high isolations, low profile, and easy planar integration, which can be adopted for the millimeter-wave (mm-Wave) LEO satellite communication system. [ABSTRACT FROM AUTHOR]

The traditional Vivaldi antenna is well known for its ultrawide bandwidth, but low gain. To enhance the radiation characteristics, we propose a new method by adding an additional structure that supports spoof surface plasmon polaritons (SSPP) as the parasitic element. The proposed patch has an enhanced gain over whole frequency band without deteriorating the bandwidth. The Sommerfeld–Zenneck wave mode and slow-wave mode benefit the gain and realize better directivity. The maximum gain could improve as high as 5 dBi. Several measured results are successfully confirmed with simulations, which demonstrate the higher directivity in the endfire direction. This design method provides a new method to improve the radiation characteristics for Vivaldi antenna. [ABSTRACT FROM AUTHOR]

A method to suppress cross frequency band scattering in multiband array (MBA) is proposed in this letter. Due to the short distance between the lower band (LB) elements and the higher band (HB) elements in MBA, the performances of the elements are distorted. By adding three L-shaped branches to each arm of LB element, the induced current can be effectively regulated, which greatly reduces the cross-band scattering ability of the array. Thus, the elements of each frequency band do not interfere with each other and work alone. This method is applied to the MBA with the interleaved scheme, which consists of one LB element with the operating frequency ranging from 0.73 to 0.86 GHz, and four HB elements with the operating frequency ranging from 1.79 to 2.41 GHz. Both simulation and measurement of proposed geometry show that this method is simple, effective, and easy to fabricate. The proposed geometry can be widely used in multiple wireless communication systems due to its high isolation, stable radiation patterns, and lower cross-band scattering. [ABSTRACT FROM AUTHOR]

This letter presents a novel class of compact dual-mode bandpass filters based on half-mode substrate-integrated waveguide (HMSIW) cavities. By using both TE102 and TE301 modes of the HMSIW rectangular cavity as resonant modes and TE101 mode as nonresonating mode, a novel HMSIW doublet with two poles and two transmission zeros (TZs) is implemented. The TZs can be located at one side or both sides of the passband. Therefore, flexible responses can be obtained. A two-pole HMSIW filter with asymmetric response and a four-pole HMSIW filter with quasi-elliptic response have been designed, fabricated, and measured, to demonstrate and verify the proposed structure. Compared with substrate-integrated waveguide (SIW) counterparts, the dual-mode HMSIW filters have the advantage of smaller size. [ABSTRACT FROM AUTHOR]

This paper presents an airborne piezoelectric micromachined ultrasonic transducers (PMUTs) operated at low frequency (40–50 kHz) for long-range detection, where the acoustic absorption loss in air is relatively low (0.8–1 dB/m). The PMUTs made with single-crystal Lead Zirconate Titanate (PZT) enables a high piezoelectric coefficient (${e} _{31, f} \approx ~16$ - 24 C/ $\text{m}^{{2}}$), and a low dielectric constant ($\varepsilon _{\mathrm {r}}~\approx ~308$), achieving high PMUT transceiver efficiency. The $2\times 2$ PMUT array achieves a very high sound pressure level (SPL) output of 109.4 dB at 26 cm distance. Different from conventional PZT PMUTs, this study utilized single-crystal PZT with a low permittivity to achieve a good acoustic reception, demonstrating the sensitivity of 2 mV/Pa. This work reports the PMUT design, modeling, fabrication, characterization, enabling a long-range detection of 4.8 meters in a pulse-echo experiment, which was conducted by a pair of $2\times 2$ PMUT arrays with the matched resonances. [2020-0270] [ABSTRACT FROM AUTHOR]

This communication presents a magnetic-material-loaded 3-D frequency-selective rasorber (FSR) consisting of independent transmission and absorption channels. The main feature of the proposed design is employing both ferrite material and meander line in the absorption channel to obtain a wide absorption band and low-loss transmission band. Detailed analysis of the absorption channel is given with the help of equivalent circuit models to demonstrate the operating principle. The design guidelines are formulated, and a design example is presented with both the simulated and measured results. The proposed FSR features both thin thickness and wide absorption bands. Moreover, no lumped components are required, which greatly facilitates the fabrication and reduces the cost. [ABSTRACT FROM AUTHOR]