Effect of air-gap on axial ratio of low profile spiral antenna

Abstract A novel design of a coplanar waveguide (CPW) feed antenna array with circular polarization (CP) and a high front-to-back ratio is described. The proposed CP array is achieved by using a compact CPW–slotline transition network etched in the ground plane. The measured results show that this kind of feeding method can improve the impedance bandwidth, as well as the axial ratio bandwidth of the CP antenna array and provide adequate gain. The proposed array can achieve a 6.08% impedance bandwidth and a 4.10% CP bandwidth. Details of the antenna design and experimental results are presented and discussed.

Download Full-text

Improved Low-Profile Helical Antenna Design for INMARSAT Applications

International Journal of Antennas and Propagation ◽

10.1155/2012/829371 ◽

2012 ◽

Vol 2012 ◽

pp. 1-5 ◽

Cited By ~ 4

Author(s):

Shiqiang Fu ◽

Yuan Cao ◽

Yue Zhou ◽

Shaojun Fang

Keyword(s):

Pitch Angle ◽

Satellite Communication ◽

Design Method ◽

Impedance Matching ◽

Axial Ratio ◽

Antenna Element ◽

Helical Antenna ◽

Copper Strip ◽

Antenna Structure ◽

Low Profile

A new low-profile variable pitch angle cylindrical helical antenna employing a copper strip as impedance transformer is proposed in this paper. Under the circumstance of a limited antenna height, the circular polarization performance of the antenna has been enhanced by changing the pitch angle and the input impedance matching has been improved by adjusting the copper strip match stub. The design method of the proposed antenna is given. The optimal antenna structure for INMARSAT application has been fabricated and measured. The measured results show that in the whole maritime satellite communication work band the VSWR is less than 1.2, its antenna gain is higher than 9 dBi, and the axial ratio is lower than 2.5 dB. The experimental results have a good agreement with the simulations. The proposed antenna is compact and easy tuning. It provides a promising antenna element for maritime satellite communication applications.

Download Full-text

Development and Miniaturized of Circularly Polarization Diversity at Cavity Backed SIW Antenna for X-Band Application

Frequenz ◽

10.1515/freq-2018-0230 ◽

2019 ◽

Vol 73 (9-10) ◽

pp. 317-320

Author(s):

Saeid Karamzadeh ◽

Vahid Rafiei ◽

Hasan Saygin

Keyword(s):

Schottky Diodes ◽

Axial Ratio ◽

Impedance Bandwidth ◽

Polarization Diversity ◽

Circularly Polarized ◽

Left Hand ◽

Low Profile ◽

X Band ◽

Coaxial Feed ◽

Good Agreement

Abstract In this work circularly polarization diversity has been achieved by utilizing two Schottky diodes on low profile cavity-backed substrate integrated waveguide (CBSIW). In comparison with other studies in the literature, the size of antenna has been reduced to 0.54λg × 0.76λg by helping a 50-Ohm coaxial feed line. The impedance bandwidth, axial ratio bandwidth and antenna gain are improved to 10.02 %, 5.2 % and 7.68dBi, respectively. In addition, the proposed antenna can generate either a left-hand circularly polarized (LHCP) or a right-hand circularly polarized (RHCP) radiation. The developed antenna was fabricated and tested and the achieved results were in good agreement with the simulated one.

Download Full-text

Beamwidth-Enhanced Low-Profile Dual-Band Circular Polarized Patch Antenna for CNSS Applications

International Journal of Antennas and Propagation ◽

10.1155/2019/7630815 ◽

2019 ◽

Vol 2019 ◽

pp. 1-13 ◽

Cited By ~ 1

Author(s):

Hongmei Liu ◽

Chenhui Xun ◽

Shaojun Fang ◽

Zhongbao Wang

Keyword(s):

Patch Antenna ◽

Ground Plane ◽

Axial Ratio ◽

Dual Band ◽

Impedance Bandwidth ◽

Coupled Line ◽

Low Profile ◽

Feed Network ◽

Single Input ◽

Half Power

A low-profile dual-band circular polarized (CP) patch antenna with wide half-power beamwidths (HPBWs) is presented for CNSS applications. Simple stacked circular patches are used to achieve dual-band radiation. To enhance the HPBW for the two operation bands, a dual annular parasitic metal strip (D-APMS) combined with reduced ground plane (R-GP) is presented. A single-input feed network based on the coupled line transdirectional (CL-TRD) coupler is also proposed to provide two orthogonal modes at the two frequency bands simultaneously. Experimental results show that the 10 dB impedance bandwidth is 32.7%. The 3 dB axial ratio (AR) bandwidths for the lower and upper bands are 4.1% and 6.5%, respectively. At 1.207 GHz, the antenna has the HPBW of 123° and 103° in the xoz and yoz planes, separately. And the values are 127° and 113° at 1.561 GHz.

Download Full-text