Chung, "A filtering diplexing antenna for dual-band operation with similar radiation patterns and low cross-polarization levels
," IEEE Antennas and Wireless Propagation Letters, In press.
However, the single offset, parabolic reflector has a high cross-polarization level
(XPOL).[1,2] In recent years, dual offset reflector systems have been used to achieve low cross polarization. For example, the Green Bank radio telescope can be operated as a single offset system or as a dual offset Gregorian configuration optimized for low XPOL.[3,4]
A cross-polarization level
of more than 30 dB is achieved in the H-plane and 26 dB in the E-plane.
Symmetric radiation patterns with low cross-polarization level
Additionally, inclusion of the SRS-EBG in the array reduces the mutual coupling by approximately -20.57 dB and slightly improves the directivity with good co- and cross-polarization levels
of the radiation patterns.
Compared to the traditional TSAs, antipodal TSAs can be fed easily with microstrip lines and SMA connectors, but it is not suitable in large array applications and its cross-polarization levels
is quite high [11-17].
Simultaneously, the simple geometry provides an easy fabrication and a reasonable cross-polarization level
. Its compact size (7 mm x 24 mm) is satisfactory to be installed in narrow locations of wireless devices.
Moreover, the measured results have maximum cross-polarization level
of about -18 dB in the XOZ plane; the front-to-back ratio is better than 22 dB over the entire band.
In order to reduce the cross-polarization level
of the radiation field while still maintaining a low level of inband scattering, we propose two modified feeding structures.
For this case, the measured radiation patterns have sidelobes lower than -10 dB and a cross-polarization level
of less than -25 dB, both of which are comparable to the patterns of a planar array with a similar aperture dimension.
In particular, the cross-polarization level
of the conformal phased array is more serious compared with the planar or linear arrays.
As shown in Figure 11(a), the measured peak side lobe level (SLL) is 19 dB below the peak gain in x-z plane while the peak cross-polarization level
is near -24 dB.