Study On Spatial Power Combining Of Gaussian Beam In Millimeter Wave Band

In human history,the time that electromagnetic wave serves as the carrier in wireless communications is more than a century,but the study of electromagnetic wave as the carrier of energy transmission was attracted attentions in recent decades.Its potential applications include wireless energy transmission,high-power millimeter wave source,millimeter wave imaging,microwave energy weapon and others,where the output power generally requires to achieve certain levels.But a single transmitter module cannot achieve such a goal.Therefore,spatial power combining and transmission are of great significance.To further enhance the power density of combined RF power,the spatial energy focusing of electromagnetic waves is also important and worthy of studying.Purpose of this work is studying how to spatially combine the RF power and convert it to Gaussian beams.The Gaussion beam can be realized by focusing.In general,the focusing can be classified as transmission type and reflection type,where the lens and reflectors are conventional types,but both suffer from some drawbacks like high cost and not flexible in design.The reflection of transmitarray is high,thus high-power applications are restricted.Therefore,the reflectarray is considered in this study.In this work,spatial power combining with Gaussian beam in millimeter wave band is studied.Based on the basic theory of Gaussian beam and near-field focusing technology,the operation mechanism of the studied scheme is discussed and further,the scheme is realized and detailed.Contributions of this work include:?1?A horn antenna working in Ka band is designed.It is designed as a standard gain of 10dBi with a aperture of 14mm×12mm.In the Ka band,the horn antenna has good reflection and radiation characteristics;the gain increases with the increase of frequency but around 10dBi.The transition is the use of a single ridge waveguide to convert the TEM mode of the coaxial cable into the TE₁₀ mode of the standard rectangular waveguide with multi-stage impedance transformers.The transition has good refelction performance of lower than-18dB in the Ka band.By using 7 horns with"triangular"arrangement,multiple feedings are used to perform the spatial power combining.?2?A new design method is proposed to generate Gaussian beam based on the operation principle of near-field focusing reflectarray.The magnitude distribution of fields at the focusing area is optimized by BFGS Quasi-Newton method,where the initial values are compensation phase that is obtained from the near-field focused reflection array.Then the optimized compensation phase is examined by full-wave EM simulations.