Planar and distributed spatial power combiners

To meet current demands for solid state high power sources distributed quasi-optical combining structures are proposed. Densely packed slotline arrays combine numerous devices efficiently but also retain broadband performance unlike planar designs (typical 10% bandwidth).; Insight into the limitations of planar power combining arrays was developed via numerical electromagnetic analysis. A code based on the finite difference time domain (FDTD) method was written. Simulated results agree with measured data for various array topologies in frequency bands ranging from microwave to submillimeter waves. Most planar designs examined exhibit highly resonant behavior. FDTD and transmission line analysis both suggest a broadband response for the proposed distributed array approach. These predictions have been experimentally validated over the Ka band (26.5-40 GHz).; A 2 x 4 active array of tapered slotlines was inserted between X-band waveguides. The amplifier module demonstrated 9.2 dB gain and 2.4 Watt output at 1 dB gain compression. Approximately 1 dB variation over the entire 8 to 12 GHz band was observed, making this high power spatial amplifier the most broadband of its kind (to our knowledge). To eliminate the presence of a lower frequency cutoff and increase the packing density of the combiner a radial arrangement of slotlines was inserted in a flared coaxial line. Initial measurements for a passive 64 element array have shown low combining loss over the 5 to 20 GHz band. The proposed radial topology has become a candidate for ultra broadband, ultra high power solid state amplifier modules.