A Broadband Planar Magic-T Using Microstrip–Slotline Transitions

The improved version of a broadband planar magic-T using microstrip-slotline transitions is presented. The design implements a small microstrip-slotline tee junction with minimum size slotline terminations to reduce radiation loss. A multisection impedance transformation network is used to increase the operating bandwidth and minimize the parasitic coupling around the microstrip-slotline tee junction. As a result, the improved magic-T has greater bandwidth and lower phase imbalance at the sum and difference ports than the earlier magic-T design. The experimental results show that the 10-GHz magic-T provides more than 70% of 1-dB operating bandwidth with the average in-band insertion loss of less than 0.6 dB. It also has phase and amplitude imbalance of less than plusmn1deg and plusmn0.25 dB, respectively.     

Slotline Stepped Circular Rings for Low-Loss Microstrip-to-Slotline Transitions

We propose a low-loss slotline (SL) stepped circular ring termination for use in a microstrip-to-slotline (MS-to-SL) transition. Not only does this termination achieve broadband characteristics, but it also reduces SL radiation. The experimental results show that, using the proposed technique, the radiation loss around the pass-band frequency is lower than that of the conventional transitions using radial or circular pad terminations