11.8 GHz GAINP/GAAS HBT dynamic frequency divider using HLO‐FF technique

Abstract

determined by the 3-dB AR, is about 540 MHz or 20.8% (2.33-2.87 GHz) and 480 MHz or 19.6% (2.21-2.69 GHz) with minimum AR of 0.87 dB at 2.6 GHz and 0.88 dB at 2.45 GHz, respectively, for L t ϭ 0 and L t ϭ 19 mm. Both of the CP bandwidths are larger than 19%. It is evident that the length of the protruded metallic strips has larger effect on the port isolation level, but has less effect on the CP bandwidth. As for the antenna with L t ϭ 19 mm, both impedance matching (referred to 10 dB return loss) and low coupling level (referred to 20 dB isolation) are achieved within the CP operating band. Figure 4 shows the measured far-field radiation patterns of the antenna with length of L t ϭ 19 mm at 2.45 GHz in the LHCP and RHCP operation. It is observed that the cross-polarization levels are about 26 dB in the broadside direction in both states. The maximum radiation direction of the antenna displaces a little from the z-axis. It should be noted that the backside radiation pattern is a mirror image of the front pattern, and the polarization senses of both sides are opposite to each other. The antenna radiates almost the same amount of energy into both sides. CONCLUSIONA novel design of broadband dual CP square slot antenna has been investigated and successfully implemented. Two orthogonal modes of the proposed antenna are excited in series through the coupling between the T-junction and the T-shaped strip. By loading the four metallic strips at the slot corners, high port isolation level is achieved. The measured 3-dB AR bandwidth is 480 MHz or 19.6% and the isolation between two ports is better than 20 dB over the band. The proposed antenna has excellent dual CP characteristics and is suitable for polarization diversity operation.