Differential Feeding Scheme Research Articles

Analysis and Design of an Ultrawideband Dual-Polarized Antenna for IBFD Applications

This communication investigates design requirements for a class of dual-polarized in-band full-duplex (IBFD) antennas utilizing a symmetry of structures and a differential-feeding scheme. The analysis reveals that, to achieve zero coupling between two ports, the out-of-phase power divider (PD) does not need to have perfect isolation and perfect matching at the two output ports. A more relaxed set of requirements for the PD is derived for the first time. Based on this, an ultra-wideband cross-shaped Vivaldi antenna is designed for IBFD applications with very high isolation. The measured 10 dB return loss bandwidth is 1.26–8.0 GHz (145.5%), while the measured port-to-port isolation is >42 dB at 1.26–4.7 GHz (115.4%) and >34 dB within the whole operational bandwidth.

High-Gain Low Cross-Polarized Dual-Polarized Filtering Patch Antenna Without Extra Circuits

This letter presents a dual-polarized filtering patch antenna with high gain, low cross-polarization, and without extra filtering circuits. By etching the slots on the patch, a radiation null at the upper band edge is generated, while introducing an extra resonant mode to broaden the impedance bandwidth. In addition, four shorting pins are symmetrically loaded on the patch, which provides a radiation null at the lower band edge and the enhanced gain. Moreover, the cross-polarization level is reduced by adopting the symmetrical structure and a differential feeding scheme. For verification, a filtering antenna operating at 5G n77 band (3.3–4.2 GHz) is designed and fabricated. The measured 10 dB bandwidth is 29.7% (3.15–4.25 GHz) with a peak gain of 9.5 dBi, a cross-polarization level of less than −32 dB and an isolation of higher than 34 dB. The out-of-band suppression levels are more than 34 and 16 dB within the lower stopband (1–2.52 GHz) and the upper stopband (4.6–6.5 GHz), respectively.

Wideband Substrate Integrated Differential Dual-Polarized Dielectric Resonator Antenna

A substrate integrated differential cavity-backed dual-polarized dielectric resonator antenna with a wide bandwidth, low profile, high isolation, and improved gain is presented. The proposed substrate integrated technique, in which the electric and magnetic walls of the cross-shaped dielectric resonator antenna (DRA) are realized by arrays of metallic and nonmetallic vias, respectively, provides the design with high level of integration and low profile. The substrate integrated DRA is differentially fed by microstrip lines through coupling slots exciting a pair of orthogonal modes for the dual polarizations. The differential feeding scheme offers a direct connection to differential systems, and greatly improves the isolation between polarizations. Benefitting from the differential coupling slots and the substrate integrated back cavity, the bandwidth is broadened and the realized gain is improved. For demonstration, a prototype is designed and fabricated. The simulated and measured results show a good agreement.

Design of Composite Microstrip-Monopole Antenna With 180$^\circ$ 1 dB Beamwidth Based on Complementary Sources Concept

A new perspective based on complementary sources radiation is presented for analyzing a widebeam composite microstrip-monopole antenna. The typical cavity model theory shows that the radiation patterns of the microstrip antenna could be calculated by using two parallel equivalent magnetic currents, and the E-plane beamwidth of the traditional microstrip antenna is mainly determined by the array factor. Loading the monopoles through the metal patch of the original microstrip antenna can construct complementary sources. Two monopoles are symmetrically loaded and two pairs of complementary sources are excited. Interestingly, the two pairs of complementary sources are aligned with in-phase magnetic current radiation sources and antiphase electronic current radiation sources, which indicates two heart-shaped radiation patterns pointing in opposite directions. The total far-zone radiated fields synthesized by the two heart-shaped radiation patterns can present wide E-plane beamwidth performance. An example antenna working at 4.4 GHz is designed for verification. With the introduction of a differential feeding scheme for a symmetrical radiation pattern, the E-plane radiation pattern can cover the upper half plane, i.e., 180°, with a fluctuation of less than 1 dB and an antenna gain of over 3 dBi.

Wideband SIW Half-Mode/Quarter-Mode-Fed Microstrip Patch Complementary Antennas With Back Radiation Suppression

Complementary sources concept and half-mode/quarter-mode substrate integrated waveguide (HMSIW/QMSIW) technology are introduced in this paper to improve the back-radiation suppression and bandwidth of microstrip patch antennas (MPAs). The HMSIW cavity as the feeding structure brings an additional resonant frequency to the inherent resonant mode of typical MPAs, which efficiently extends the bandwidth of the MPAs. In addition, while stimulating the MPA mode, the HMSIW cavity drives a monopole by slightly breaking the shorting wall of the HMSIW cavity and loading a printed monopole. The loaded monopole and the equivalent magnetic currents of the MPA construct an orthogonal complementary source model that indicates back radiation suppression. A differential feeding scheme is also employed to enhance the radiation performance. The dual-polarized model, achieved by replacing the HMSIW cavity with QMSIW cavities, is also addressed and even fabricated and tested. The measured results show a differential impedance bandwidth of 15.4% from 1.91 GHz to 2.23 GHz with a differential port-to-port isolation of 38 dB. In the operating band, the average gain is 7.5 dBi, and the front-to-back ratio (FBR) is over 18 dB with a maximum value of 34 dB.

Dual‐polarised high‐gain triple‐band differential antenna for WLAN and Sub‐6 GHz 5G applications

A new dual-polarised high-gain triple-band differential-fed antenna is proposed in this study. The antenna adopts a differential feeding scheme, in which a high-frequency radiator for 3.5 GHz Sub-6 GHz 5G band and 5 GHz WLAN band, and two pairs of low-frequency radiators for 2.45 GHz WLAN band are effectively combined to obtain multiband operation. To filter out unwanted frequency band, four half-wavelength slots are introduced to generate a notch band between 3.8 and 4.8 GHz. Experimental results show that the proposed antenna achieves 10-dB impedance bandwidths of 2.37-2.61 GHz for the low-frequency band, 3.27-3.76 GHz for the intermediate frequency band, and 4.87-5.98 GHz for the high-frequency band. The gains of the antenna are all above 8.0 dBi for all the three bands. The antenna exhibits a good directivity and low cross-polarisation level (below -20 dB); thus it is a good candidate for WLAN and Sub-6 GHz 5G wireless access point systems.

Dual-Band Differential Shifted-Feed Microstrip Grid Array Antenna With Two Parasitic Patches

A dual-band differential shifted-feed microstrip grid array antenna (DSF-MGAA) with two parasitic patches is presented in this communication. By moving the feed location, a conventional MGAA (C-MGAA) can be turned into an SF-MGAA for dual-band operation. The high-frequency band of SF-MGAA corresponds to the operation mode of the C-MGAA, and its low-frequency band is similar to that of the patch or meshed patch antenna. A new differential feeding scheme and two parasitic patches are adopted to improve the impedance bandwidth of SF-MGAA. The proposed DSF-MGAA can cover a dual band of 3.7 and 28.5 GHz. The measured −10 dB impedance bandwidths of 3.4% and 4.5%, which correspond to the peak gains of 8.98 and 19.2 dBi, are obtained in the low- and high-frequency bands, respectively. The DSF-MGAA can be a potential candidate for the future dual-band wireless communication.

Wideband low‐profile low‐temperature co‐fired ceramic patch antenna with a differential‐fed structure

A novel wideband patch antenna with a differential-fed structure is proposed in this study. For this antenna, an H-shaped patch is first adopted to build a compact design. Then, by introducing a via-wall-plate pair as the differential feeding scheme, favourable radiation patterns and enhanced operating bandwidth can be achieved in a low profile. Furthermore, a Marchand balun is incorporated into the overall design to facilitate the test and direct integration with existing single-end radio-frequency circuits. The proposed antenna, which is designed and fabricated, using low-temperature co-fired ceramic technology, could be used to develop a highly integrated system-in-package. The measured results demonstrate that the proposed antenna with a low profile of 0.06λ 0 obtains an impedance bandwidth of 11.2%, a peak gain of 7.1 dBi, and a low cross-polarisation of better than −20 dB.

Differential Dielectric Resonator Filters

This paper presents a detailed investigation of the differential bandpass filters with high performance using the popular TE $_{\mathrm {01\delta }}$ -mode ring-shaped dielectric resonator (DR). According to the field distribution of the TE $_{\mathrm {01\delta }}$ mode, the design principle for differentially exciting it is constructed, i.e., a pair of feeding probes should be face-to-face. Under this feeding scheme, it can be found that the resonant modes of the DR cavity can be divided into two kinds of responses, i.e., differential-mode and common-mode responses. Furthermore, the differential feeding scheme is flexible, and then two modified differentially fed structures by changing the positions of differential port pair are introduced to improve the filter selectivity by incorporating an additional transmission zero or to enable the filter to meet the requirement of integration with other differential devices. To validate the proposed idea, several design examples of the differential DR filters are presented, and their simulated and measured results are given.

Balanced bandpass filter with spurious mode suppression

ABSTRACTThis article presents a new and simple design approach for the balanced bandpass filter (BPF) with spurious mode suppression using half‐wavelength resonators. The second harmonic of the resonator, acting as the lowest‐frequency common‐mode (CM) noise, is suppressed by using a new differential feeding scheme. Furthermore, an electrically coupled structure, exhibiting a bandstop response at the third harmonic of the resonator [acting as the lowest‐frequency differential‐mode (DM) spurious], is introduced. As a result, both wideband CM suppression and extended DM upper stopband can be realized simultaneously due to the suppression of the second and third harmonics of the resonator. For demonstration, a second‐order balanced BPF is designed, fabricated, and measured. Good agreement between simulated and measured results can be observed. © 2017 Wiley Periodicals, Inc. Microwave Opt Technol Lett 59:1188–1190, 2017

Differential grid array antenna to radiate pencil beam at 24 GHz for radar and sensor applications

A new differential grid array antenna that radiates a pencil beam is reported. The difference between the half-power beam widths of the E- and H-planes is used to assess the pencil beam quality. Also, a novel differential feeding scheme that eases the testing and improves the pencil beam quality, impedance matching and gain bandwidth is proposed. The prototype was designed and fabricated on RT/duroid 5880 substrate with the size of 40 × 50 × 0.787 mm3 and the number of 16 radiating elements. Measured results show that the differential grid array antenna achieved 4.37% impedance bandwidth and 17 dBi gain at 24.25 GHz.

Analysis and Design of a Differentially-Fed Frequency Agile Microstrip Patch Antenna

The design of a frequency agile microstrip patch antenna is described that is readily interfaced with differential RF transceivers. By integrating three pairs of varactor diodes with the patch antenna, and tuning them in unison, frequency tuning ratios approaching 2 are possible with the design. This is made possible by the intrinsically broadband nature of the differential feeding scheme used. An intuitive equivalent circuit for predicting the port characteristics of the antenna is presented. Moreover, the circuit is shown to be highly accurate in predicting losses produced by the varactor diodes and the consequent radiation efficiency of the antenna. To the best of the authors' knowledge, this is the first time a detailed analysis of the effect of varactor diode losses has been undertaken in frequency agile antennas using an equivalent circuit. The equivalent circuit model is subsequently validated using full-wave simulations and experimental measurements of an antenna operating in the 2-4 GHz range.

Broadband Patch Antenna With a Folded Plate Pair as a Differential Feeding Scheme

A broadband differential-fed patch antenna (DFPA) with good radiation pattern is proposed and studied. Unlike conventional DFPAs, the proposed antenna employs a folded plate pair as the differential feeding scheme. The devised feeding approach subtly acts as an impedance matching media for two radiation modes of the antenna, conducing to the wide impedance bandwidth. The conceived bandwidth enhancement technique demonstrates an impedance bandwidth (SWR les2) of up to 74% which outperforms conventional broadband patch antennas of more than 20%. Meanwhile, by using a differentially-driven signal along with the introduced feeding scheme, symmetric radiation patterns, low cross-polarization levels and stable radiation patterns are realized within the band. More importantly, the antenna has a stable gain at 8.5 dBi within a wide frequency range, demonstrating the high stability of the radiation characteristics for the two radiation modes. Analysis and parametric studies of the proposed feeding structure are provided.

Broadband patch antenna with low cross-polarisation

A broadband differential-fed patch antenna with good radiation pattern is proposed. Unlike conventional differential-fed patch antennas, the proposed antenna employs a folded plate pair as the differential feeding scheme. To demonstrate the devised feeding approach, impedance bandwidth of up to 74% (SWR<2) has been achieved. More importantly, symmetric radiation pattern, low-cross polarisation level and stable radiation pattern are realised within the band.