Cross-polarization characteristics of a probe-fed spherical-circular microstrip patch antenna

1993 ◽  
Vol 6 (12) ◽  
pp. 705-710 ◽  
Author(s):  
Hong-Twu Chen ◽  
Kin-Lu Wong
2015 ◽  
Vol 13 ◽  
pp. 251-268 ◽  
Author(s):  
D. Vollbracht

Abstract. The antenna cross polarization suppression (CPS) is of significant importance for the accurate calculation of polarimetric weather radar moments. State-of-the-art reflector antennas fulfill these requirements, but phased array antennas are changing their CPS during the main beam shift, off-broadside direction. Since the cross polarization (x-pol) of the array pattern is affected by the x-pol element factor, the single antenna element should be designed for maximum CPS, not only at broadside, but also for the complete angular electronic scan (e-scan) range of the phased array antenna main beam positions. Different methods for reducing the x-pol radiation from microstrip patch antenna elements, available from literature sources, are discussed and summarized. The potential x-pol sources from probe fed microstrip patch antennas are investigated. Due to the lack of literature references, circular and square shaped X-Band radiators are compared in their x-pol performance and the microstrip patch antenna size variation was analyzed for improved x-pol pattern. Furthermore, the most promising technique for the reduction of x-pol radiation, namely "differential feeding with two RF signals 180° out of phase", is compared to single fed patch antennas and thoroughly investigated for phased array applications with simulation results from CST MICROWAVE STUDIO (CST MWS). A new explanation for the excellent port isolation of dual linear polarized and differential fed patch antennas is given graphically. The antenna radiation pattern from single fed and differential fed microstrip patch antennas are analyzed and the shapes of the x-pol patterns are discussed with the well-known cavity model. Moreover, two new visual based electromagnetic approaches for the explanation of the x-pol generation will be given: the field line approach and the surface current distribution approach provide new insight in understanding the generation of x-pol component in microstrip patch antenna radiation patterns.


A small size and very thinwideband dipole microstrip patch antenna for dual frequency operation is designed and analysed in this paper. The dimension of the proposed antenna is 40×30×1.6 mm3 .The proposed antenna is designed using a low cost and reliable FR4 substrate. This FR4 substrate material has a thickness of 1.6 mm, dielectric constant of 4.4 and loss tangent of 0.02. The proposed antennaresonates at 2.19 GHz and 2.5 GHz frequencies with a -10 dB impedance bandwidth of 4.37 GHz, ranging from 1.8 GHz to 6.17 GHz.This shows the proposed antenna bandwidth is increased to 200%. The VSWR of the proposed antenna is less than 2 for entire operating frequency range. Radiation efficiency is above 70% at both of the resonance frequencies. A very low cross polarization is found at all resonance frequencies. CST Microwave Studio is used to design and analyse the proposed antenna.


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