Jia-Yue Zhao

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.

High-Efficiency Compact Circularly Polarized Microstrip Antenna With Wide Beamwidth for Airborne Communication

The letter presents a compact circularly polarized (CP) microstrip antenna for airborne communications. The antenna adopts a square radiation patch with a cross slot to reduce the antenna dimensions and improve the impedance matching. For the high radiation efficiency of the proposed antenna, the no-resistor series feeding network is utilized to construct the antenna. In addition, the proposed structure also brings a superwide beamwidth in axial ratio (AR) radiation patterns. To confirm the performances of the novel structure, an L-band prototype of the antenna is manufactured and tested. The thickness and the side length of the antenna are 0.073λ0 and 0.275λ0, respectively (λ0 is the wavelength in free space). The impedance bandwidth for VSWR ≤ 2 reaches 22.4%, and the AR bandwidth for AR ≤ 3 dB reaches 6.8%. In the overlap band, the radiation efficiency of more than 97% and the gains of more than 5.2 dBic are obtained. Especially, the beamwidth for AR ≤ 3 dB can cover more than 180°.

Wideband Unidirectional Bowtie Antenna with Pattern Improvement

A wideband unidirectional bowtie antenna with stable radiation patterns is proposed and investigated. It is fed by a wideband microstrip balun, using a coupling triangular structure to induce more balanced currents. Particularly, the corners of the conventional triangular bowtie dipole are rounded to achieve an impedance BW of 106.9% for jS11j • i10dB ranging from 1.97GHz to 6.49GHz. Additionally, a special small circular re∞ector between the ground plane and the bowtie dipole is used to stabilize the radiation patterns. The antenna achieves a stable gain of around 9.5dBi with a little variation of 1.4dBi and unidirectional radiation patterns over the whole operating band.

Printed UWB MIMO Antenna with Different Polarizations and Band-Notch Characteristics

A novel ultra wideband (UWB) multiple-input-multiple-output (MIMO) antenna with difierent polarizations and band-notch characteristics is proposed in this letter. The antenna consists of two monopole antenna radiating elements with gradual change structure, which are placed perpendicularly to each other and printed on each side of the substrate to achieve a wide bandwidth and difierent polarizations. Band-rejected flltering property in the WLAN band is achieved by etching a H-shaped slot and employing a resonant L-shaped strip on two antenna elements. The proposed antenna has a small size of 27£37£1mm 3 with a bandwidth of 128.6% (2.35{10.82GHz). Within the required band, the isolation for the two ports exceeds 18dB. The envelope correlation coe-cient is also measured.

Dual-Polarized Crossed Bowtie Dipole Array for Wireless Communication Applications

A dual-polarized array with downtilted radiation patterns is proposed for wireless communication applications. The proposed dual-polarized antenna element achieves an enhanced impedance bandwidth and compact dimensions by introducing a parasitic circular patch and vertical metal cylinders, which is a good candidate for radiating elements in base station antennas. By optimizing the amplitude and phase distribution along the feed, a radiation pattern with a downtilted angle is obtained. The dual-polarized array antenna achieves an impedance bandwidth for VSWR 1.5, covering the frequency bands for 3G/LTE systems. Moreover, the proposed array achieves high port isolation, the stable antenna gain over the entire operating band. Therefore, the proposed array antenna is very suitable for potential wireless communication applications. A prototype has been manufactured and measured. The measurements, that match the design objectives, are also presented.

Dual-Polarized Cross Bowtie Dipole for 3G and LTE Applications

A dual-polarized cross bowtie dipole element with parasitical circular patch and vertical metal cylinders for base station antennas is presented. A pair of orthogonal cross bowtie dipoles, with a reflector ground plane, is used to obtain the two linear polarizations. Besides two inverted L-shaped feed strips and two shorted feed baluns, parasitical circular patch is introduced to improve the impendence bandwidth and vertical metal cylinders are employed to decrease the lateral dimensions of the antenna. A wideband impedance characteristic of about 45.6% for VSWR ≤ 1.5 (

Wideband Patch Antenna with Stable High Gain and Low Cross-Polarization Characteristics

A wideband unidirectional patch antenna with two meandering strips and a i-shaped feeding structure is designed. The investigation shows that the antenna achieves an impedance bandwidth of 54.2% for VSWR • 2 and a stable gain of around 9dBi. The far fleld radiation patterns with low cross polarization which levels are less than i27dB, low back radiation and symmetrical E- and H-plane patterns are obtained over the whole operating frequency range.

Compact printed ultra-wideband antenna with dual band-notched characteristics

A novel compact ultra-wideband (UWB) printed planar antenna with dual band-notched characteristics is proposed. The patch with gradual change structure produces a wide bandwidth from 2.8 to 12GHz. By employing a resonant I-shaped strip and etching a U-slot in the radiation patch on the front side, band-rejected filtering properties in the WiMAX/WLAN bands can be achieved. Experimental results show that the presented antenna has a wide bandwidth from 2.8 to 12 GHz with dual band notches.

CPW-fed UWB antenna with the design of controllable band notch

In this letter, a novel CPW fed UWB antenna is presented which has controllable band-notch frequency characteristic. The proposed antenna has a large bandwidth covering the frequency band from 3.3GHz to 10.6GHz, and small size with the dimension of only about one quarter of the wavelength. By introducing an L-shaped slot in the ground plane a controllable notching band can be achieved. And good band-notched performance from 5.0GHz to 6.0GHz can be obtained. The overall dimension of the antenna is about 28×21×1.6 mm3. Measured results are in good agreement with simulation ones and show that this proposed antenna is suitable for UWB applications due to its band-notched characteristic restraining the impact of WLAN efficaciously.