Compact Branch-line Power Divider Using Connected Coupled-line Structure

In order to improve performance for the size of the BLPD, the CCL is used for the realization as the delay line. As realizing lower coupling coefficient and lower characteristic impedance, the CCL has good performance of the phase delay. The CCL is applied as the compact BLPD with optimized coupling factor and matched impedance because the lower coupling coefficient and lower characteristic impedance are increased the size and the loss, respectively. Designed BLPD using the CCL has the size of $0.13{\lambda}_g{\times}0.13{\lambda}_g$ and the size-reduction ratio of fabricated BLPD using the CCL has 58.5% ($21.08{\times}21.40mm^2$). Also, fabricated BLPD is measured the insertion loss of 3.16dB at the center frequency of 1.78GHz and the 20dB bandwidth is 9.58%. Differenced magnitude and phase between threw port and coupled port are measured 0.1dB and $89.9^{\circ}$, respectively. These performances are almost same compared with the conventional BLPD. Suggested application of the CCL can be used various devices and circuits for the size-reduction.