Hybrid Feed Research Articles

Wideband modified L-probe fed circularly polarized patch antenna with conical beam radiation pattern

A wideband circularly polarized patch antenna with conical beam radiation pattern is presented. The antenna structure is composed of a circular patch, two modified L-shaped probes, and a wideband 90° hybrid feed network. The higher mode of TM21 mode is excited on the circular patch to produce the conical beam radiation pattern. The proposed antenna has a measured common operating bandwidth with 10-dB return loss, 3-dB axial ratio bandwidth, and good conical beam radiation pattern is about 20.1% with respect to the center frequency of 2.9 GHz from 2.6 to 3.2 GHz. The average gain of the proposed antenna is about 6.5 dBi over the operating band. Good agreement is observed between the simulated and measured results.

접고 펼침에 따라 다이버시티와 지향성 모드로 변환이 가능한 평면형 안테나 어레이

본 논문은 다이버시티 모드와 지향성 모드를 스위치 할 수 있는 평면형 안테나 구조를 제안하였다. 제안된 구조는 네 개의 안테나 요소들을 한 평면에 배열했을 경우, 높은 격리도를 가지며 다이버시티 모드로 동작한다. 한편, 네 개의 안테나 요소들을 수직으로 적층 배치한 구조는 지향성 모드로 동작한다. 이 경우, 네 개의 안테나 요소들은 적층형 Yagi-Uda 안테나 구조를 따르며, 높은 이득을 갖도록 최적화되었다. 특히, 네 개의 안테나 요소에 두 가지의 급전 방법과 구부러진 급전선을 사용하여 성능을 극대화 시켰다. 2.4 GHz에서 동작하는 제안된 안테나는 시뮬레이션 결과와 실험적인 결과가 일치하는 것을 확인하였으며, 각 모드에서의 성능 또한 입증하였다. In this paper, a novel diversity and directivity mode-switchable planar antenna array is proposed. For the diversity mode, four elements are unfolded on the plane and high isolation can be achieved. On the other hand, the antenna function is changed to the directivity mode when they are folded and stacked. Each element works such as a stacked Yagi-Uda antenna with high directivity. Especially, the curved feed line as well as the hybrid feeding method is used to improve performances. The simulation results agree well with measurement results and it is successfully demonstrated that two modes are properly working at 2.4 GHz.

Wideband Circularly Polarized Antenna With Gain Improvement

A wideband circularly polarized antenna with coaxial balun feed, using a broadband 90° hybrid feed network, is proposed. By introducing a narrow patch connecting the pair of bowtie dipoles as an entity that increases the effective radiation area, the proposed antenna delivers a higher gain than that of the conventional dual-fed-type circularly polarized antenna. It can achieve a measured impedance bandwidth for VSWR ≤ 1.5 of 57% and a 3-dB axial-ratio bandwidth of 51.8%. Moreover, the antenna has stable peak circularly polarized gain better than 9.0 dBi ranging from 1.1 to 1.6 GHz. For the entire half-power beamwidth, the axial ratio can be kept below 3 dB.

Design and control of a novel hybrid feed drive for high performance and energy efficient machining

Achieving sustainability in manufacturing requires that the energy consumption of manufacturing machines be reduced without unduly sacrificing their speed and accuracy. This paper presents the design and control of a novel feed drive whose actuation method and drive configuration change depending on the mode of the machining operation. During rapid traverse, the table is driven at its center of gravity using a linear motor. When cutting begins, the table automatically couples to a motor-driven shaft, while the linear motor provides active vibration damping and quasi-static error compensation. Improvements in speed, accuracy and/or energy efficiency over conventional drives are experimentally demonstrated.

IN-EAR DIGITAL ELECTRONIC NOISE CANCELLING AND COMMUNICATION DEVICE

A noise canceling and communication system is described. An in-ear device is adapted to fit in the ear canal of a device user. A passive noise reduction element reduces external noise entering the ear canal. An external microphone senses an external acoustic signal outside the ear canal to produce a representative external microphone signal. An internal microphone senses an internal acoustic signal proximal to the tympanic membrane to produce a representative internal microphone signal. One or more internal sound generators produce a noise cancellation signal and an acoustic communication signal, both directed towards the tympanic membrane. A probe tube shapes an acoustic response between the internal sound generator and the internal microphone to be relatively constant over a wide audio frequency band. An electronics module is located externally of the ear canal and in communication with the in-ear device for processing the microphone signals using a hybrid feed forward and feedback active noise reduction algorithm to produce the noise cancellation signal. The noise reduction algorithm includes a modeling component based on a transfer function associated with the internal sound generator and at least one of the microphones to automatically adjust the noise cancellation signal for fit and geometry of the ear canal of the user. The communication component also includes a modeling component based on a transfer function associated with the internal sound generator and at least one of the microphones to automatically adjust the communication signal for fit and geometry of the ear canal of the user and to assure that the communication signal does not interfere with the noise reduction algorithm and that the noise cancellation signal does not interfere with passing of the communication signal.

Dual-band dual-polarised microstrip array with fractional frequency ratio

An S/X dual-band dual-polarised shared aperture microstrip array with fractional frequency ratio (FR=1:3.5) is presented. A hybrid feed is adopted in this phased array to improve the isolation. Measured results agree well with the simulation, exhibiting a |S11|≤15 dB bandwidth of 10% in both bands. Good polarisation-isolation and radiation pattern are also confirmed.

Design of Compact Dual-Polarized Antennas for MIMO Handsets

A design method of compact dual-polarized antennas has been proposed for multiple input and multiple output (MIMO) handset application. For the sake of high isolation in dual polarizations, a printed monopole and a hybrid slot antenna are combined using a coplanar waveguide (CPW) and microstrip hybrid feeding structure. The proposed topology will result in orthogonal current distribution modes for the different polarizations, which effectively reduces the mutual coupling of the two modes. The operation mechanism of the feeding structure is analyzed in principle and verified by simulation. Simulated and measured results show this compact dual-polarized antenna achieves isolation between the two ports of better than 25 dB, and the relative bandwidth is wider than 23.5%.

Hybrid waveguide–stripline feeding network for dual polarised arrays at K band

This study demonstrates a hybrid technology for the implementation of efficient feeding networks in K-band arrays. In the proposed hybrid structure, the main part of the distribution network consists of dielectric-loaded E-plane metallic waveguides, whereas stripline circuits that depart from the waveguides are used to feed the radiators. The efficiency of the hybrid feeding network is verified on a 4×4 dual-polarised array of circular waveguides operating in the K band. Details on the characteristics of the loaded waveguide and the array elements, and on the construction of the overall structure are given. Measured results are presented and discussed in order to demonstrate that the hybrid waveguide×stripline structures are a promising technology for the creation of efficient feeding networks at higher frequencies.

Dielectric Resonator Direction Finding Antenna

The idea of using a cylindrical dielectric resonator antenna for mechanical direction finding and target tracking is presented. The hybrid feeding network of the receiving antenna comprised two ports: one for the broadside-type sum pattern and another for the monopole-type difference pattern. The proposed design is fabricated and tested experimentally for concept validation. Both linearly polarized patterns were obtained around 2.6 GHz. The coupling between the sum and difference ports is measured to be smaller than −30 dB, and the 3 dB width of the minimum in the difference pattern is 10°.

A Dual-Polarized Microstrip Patch Antenna Using Hybrid Feed

A new dual-polarized microstrip patch antenna fed by probe feed and aperture coupled feed is presented. The hybrid feed, a T-shaped microstrip feedline, is adopted to improve the isolation between two ports, and the “hour-glass” shaped slot is used to improve the input impedance of the proposed antenna. The measured center frequency is 2.37 GHz, the return loss for port 1 is −16.08 dB and −21.92 dB for port 2, and the isolation between the two ports is −24.24 dB. Finally, four slots are embedded along the centerline of the ground plane so that the bandwidth of antenna is greatly improved. Good agreement between the measured and simulated results has been achieved.

DUAL-POLARIZED DIELECTRIC RESONATOR ANTENNA WITH HIGH ISOLATION USING HYBRID FEEDING MECHANISM FOR WLAN APPLICATIONS

A dual-feed dual-polarized dielectric resonator antenna (DRA) with high isolation is proposed in this paper. The high isolation is achieved by using two hybrid feeding mechanism: one port having an H-shaped aperture coupled feed and the other with two out-of- phase probe feeds. The antenna is designed to operate at around 5.2GHz for WLAN (Wireless Local Area Network) applications and experimental results show that it has more than 35dB isolation over the entire impedance bandwidth. Good symmetric broadside radiation patterns with low cross polarizations are observed in the two principal planes, and in addition, the front-to-back (F/B) ratios for Port 1 and Port 2 are 10 and 18dB, respectively.

A Novel Hybrid-Fed Patch Antenna With Pattern Diversity

Abstract-In this letter, a novel hybrid-fed circular patch antenna operating with TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sub> and TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">01</sub> modes is presented. By making use of a hybrid feed network, the two modes can be operated at an overlapped frequency range for 2.4-GHz WLAN applications, while TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sub> mode reveals good broadside radiation patterns and TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">01</sub> mode shows monopole-like radiation patterns. The proposed antenna is fabricated and tested. The measured gain for the broadside mode is 7.1-9.1 dBi from 2.16 to 2.72 GHz (23.0%), and for the conical mode 3.4-4.3 dBi from 2.14 to 2.64 GHz (20.5%). High isolation (<; -40 dB) between the two feeding ports for the entire impedance bandwidth of the proposed antenna is achieved. The planar dual-port antenna provides different patterns and polarizations to take advantage of the pattern and polarization diversity for modern mobile communications.

Low-cost printed antenna array built with hybrid feed for urban microwave links

This study presents a new millimetre-wave printed antenna array fed by a rectangular waveguide. This compact, light and low-cost antenna, composed of a large number of linear subarrays of patches fed by a waveguide drilled in the ground support, is well suited to urban microwave links for cellular base stations. Measurements show a peak gain of 30 dBi with an efficiency of 69%.

Broadband Circularly Polarized Annular-Ring Microstrip Antenna

A wideband circularly polarized (CP) annular-ring patch antenna with two proximity-coupled L-probe feeds orientated to have phases of 0deg and 90deg, using a broadband 90deg hybrid feed, is proposed. It is found that the current distribution for CP operation can be improved by cutting a smaller concentric circular slot on the original larger circular patch to form an annular-ring patch. With such an arrangement, the proposed antenna delivers a wider axial ratio (AR) bandwidth than that of the conventional circular patch with the identical feeding technique. Considering the common overlapped bandwidth limited by the impedance, AR and gain, the proposed annular-ring patch antenna exhibits an effective bandwidth of 38% from 1.5 to 2.2 GHz, which is wider than the corresponding bandwidth of 29.7% from 1.35 to 1.82 GHz for the conventional circular patch. Moreover, the effective bandwidth of 38% for the proposed annular-ring antenna is also much wider than those for the other annular-ring patch antennas in the literature.

Analysis of circularly polarised dual-ring microstrip patch array using hybrid feed

Design and analysis of a series-fed, circularly polarised, dual-ring array using hybrid feed are presented. Two concentric ring subarrays with different element numbers formed by linearly polarised microstrip patches are arranged and energised by a hybrid feed network sequentially to generate circular polarisation (CP). The radiating elements are connected in cascade and fed by non-radiating apertures with power coupled from a lossy feeding circuit. A schematic model is developed for power distribution of the radiating elements in the array so that each will receive identical amount of power, which is essential to produce CP waves. This model can be applied on various types of series-fed arrays using non-resonant feeds as long as the power coupling mechanism is formed. The proposed design is validated through measured data, which demonstrated good CP quality, well-defined radiation patterns and moderately high gain.

Dual-polarised dielectric resonator antenna with high isolation and low cross-polarisation

A novel, dual-polarised dielectric resonator antenna with high-isolation and low cross-polarisation is presented using a hybrid feeding technique. Port isolation of 35.9 dB and a cross-polarisation level of −34 dB are measured. The impedance bandwidth of return loss less than −10 dB is 440 MHz (7.9%) with a centre frequency of 5.7 GHz. Since its feeding mechanism is symmetric, a symmetric radiation pattern is also achieved. It is suitable for the application of synthesis aperture radar and some wireless systems.

Wideband Circularly-Polarized Patch Antenna

A novel wideband circularly-polarized patch antenna is presented. First, a new broadband 90deg hybrid feed network is proposed to have a bandwidth of 75% for the 10-dB return loss, good two output ports amplitude balance and a consistent 90deg (plusmn3deg) phase difference between two output ports. Then, a circular patch antenna fed by four sequential-rotation proximity-coupled L-probes orientated to have phase of 0deg, 90deg, 180deg and 270deg is presented. The four L-probes are connected to the respective ports of a feed network comprising a pair of the proposed broadband 90deg hybrid. It is found that the antenna can deliver a measured impedance bandwidth of 79.4% from 1.04 to 2.41 GHz for SWR<2, measured 2-dB and 3-dB axial-ratio bandwidths of 57% from 1.3 to 2.35 GHz and 82% from 1 to 2.4 GHz, respectively, and a measured gain bandwidth of 56.1% from 1.26 to 2.32 GHz for gain>3 dBi. The simulated impedance bandwidth is 94% from 0.9 to 2.5 GHz for SWR<2. The simulated 3-dB axial-ratio bandwidth is 63.8% from 1.25 to 2.42 GHz. The simulated gain bandwidth is 59.3% from 1.33 to 2.45 GHz for the gain>3 dBi. Good agreement is observed between simulation and measurement

Fitness consequences of hybridization between house sparrows (Passer domesticus) and tree sparrows (P. montanus)

Gene transfer may occur following hybridization between closely related species if hybrids are viable and able to breed with individuals of one or both of the parental species. House (Passer domesticus) and tree sparrows (P. montanus) occasionally hybridize and produce viable offspring. Previously, we concluded that male tree × house sparrow hybrids are most probably fertile based on the observation of a male F1 hybrid feeding the nestlings with a female house sparrow in two consecutive clutches. However, recent DNA analyses based on blood samples revealed that all nestlings (4) in the first clutch were sired by a neighbouring house sparrow male, whereas nestlings in the second clutch (2) were not blood sampled and most probably died before fledging. This indicates that extensive extra-pair fertilization confounded our previous conclusion, and indicates that social partnership and attending behaviour can be imprecise measures of paternity.

A Wideband Circularly Polarized Conical-Beam Patch Antenna

A circularly polarized conical-beam patch antenna that employs a hybrid feeding mechanism for wideband operation is presented in this paper. It is implemented through using a pair of L-probes and apertures, which are connected by the feeding network, to excite the circular patch in orthogonal directions. The patch is supported by two plastic posts of 0.084 lambda0 height in the air, where lambda0 is the free-space wavelength at 2.53 GHz. This antenna possesses an impedance bandwidth of 28.2% (SWR<1.5) and an axial ratio bandwidth (AR<3 dB) of 28.3%. Also, it has left-hand circularly polarized conical patterns with the peaks located at around thetas=plusmn33deg over these bandwidths. Moreover, its 3-dB gain bandwidth and peak gain are 32.4% and 5.5 dBic, respectively

Dual-polarized dielectric resonator antennas

Two high input-isolation dual-polarized dielectric resonator (DR) antennas are presented in this communication. First, a slot-coupled feed technique with two narrow slots forming a T configuration is employed to design a dual-polarized DR antenna. Input isolation exceeding 35 dB has been obtained in the band for this design. Secondly, a hybrid feed mechanism with a coplanar waveguide (CPW) feed and a slot feed is used to achieve a dual-polarized DR antenna. A vertical strip is added at the center strip of the CPW feed to improve the coupling to the DR antenna. Also, input isolation exceeding 35 dB has been obtained in the band. Good cross-polarization levels less than -20 dB in the broadside direction are attained. The measured far-field radiation patterns are stable in the passband and the measured gains are around 5.5 dBi for the two feed ports of both cases.