TM surface-wave power combining by a planar active-lens amplifier

Power combining of TM surface waves by a planar active-lens amplifier is the subject of this paper. An amplifier gain of 11 dB at 8.25 GHz with a 3-dB bandwidth of 0.65 GHz has been demonstrated. Gain is measured from input to output connector to facilitate comparisons with more conventional amplifiers. Measurements of output power versus input power are also presented. The amplifier behaved in a linear manner and no problems with spurious oscillations were encountered. Construction of the amplifier is compatible with planar fabrication technologies. A key component of the combiner is a microstrip-fed Yagi-Uda slot-array antenna for TM surface-wave excitation of a thick dielectric slab. Design and optimization guidelines for the antenna are presented as well as detailed spectral-domain and finite-difference time-domain (FDTD) analysis results. Measured and simulation results show an input return loss and front-to-back ratio better than 10 dB over a 5% bandwidth. Calculated and measured results for the fields radiated by the antenna confirm forward radiation of the dominant TM mode in the thick dielectric slab. Integration of the computed radiated fields shows the antenna has a surface-wave launching efficiency of 85%.

[1]  Stephen S. Attwood,et al.  Surface‐Wave Propagation Over a Coated Plane Conductor , 1951 .

[2]  Zoya Popovic,et al.  Two-level power combining using a lens amplifier , 1994 .

[3]  W. Rotman,et al.  Wide-angle microwave lens for line source applications , 1963 .

[4]  R. C. Compton,et al.  Thermal management for high-power active amplifier arrays , 1996 .

[5]  J. W. Mink,et al.  Quasi-Optical Power Combining of Solid-State Millimeter-Wave Sources , 1986 .

[6]  T. Itoh,et al.  Surface wave excitation of a dielectric slab by a Yagi-Uda slot array antenna-FDTD simulation and measurement , 1997, 1997 Topical Symposium on Millimeter Waves. Proceedings (Cat. No.97TH8274).

[7]  N. Kolias,et al.  A monopole-probe-based quasi-optical amplifier array , 1997 .

[8]  Michael B. Steer,et al.  Two-dimensional quasi-optical power combining system: performance and component design , 1996, 1996 IEEE MTT-S International Microwave Symposium Digest.

[9]  T. Itoh,et al.  Directive Planar Excitation of an Image-Guide , 1981, 1981 IEEE MTT-S International Microwave Symposium Digest.

[10]  J. Harvey,et al.  Demonstration of an oscillating quasi-optical slab power combiner , 1995, Proceedings of 1995 IEEE MTT-S International Microwave Symposium.

[11]  Robert M. Weikle,et al.  A 100-MESFET planar grid oscillator , 1991 .

[12]  T. Itoh,et al.  TE surface wave power combining by a planar 10-element active lens amplifier , 1997, 1997 IEEE MTT-S International Microwave Symposium Digest.

[13]  J. Harvey,et al.  A dielectric slab waveguide with four planar power amplifiers , 1995, Proceedings of 1995 IEEE MTT-S International Microwave Symposium.

[14]  Tatsuo Itoh,et al.  Surface wave excitation of a dieletric slab by a Yagi-Uda slot array antenna , 1996, 1996 26th European Microwave Conference.

[15]  A. Alexanian,et al.  Broadband waveguide-based spatial combiners , 1997, 1997 IEEE MTT-S International Microwave Symposium Digest.

[16]  Tatsuo Itoh,et al.  A 10-element active lens amplifier on a dielectric slab , 1996, 1996 IEEE MTT-S International Microwave Symposium Digest.

[17]  Michael B. Steer,et al.  Quasi-optical power combining in a dielectric substrate , 1995, Proceedings of ISSE'95 - International Symposium on Signals, Systems and Electronics.

[18]  J. W. Mink,et al.  A hybrid dielectric slab-beam waveguide for the sub-millimeter wave region , 1993 .