Selective layer millimeter-wave surface-heating system and method

1. A surface-heating system comprising:

an active reflect-array antenna system to provide a collimated high-power wavefront at a millimeter-wave frequency in a direction of a surface to heat the surface within a surface depth by amplifying and reflecting a spatially-fed millimeter-wave lower-power wavefront; and

a low-power feed to provide the spatially-fed millimeter-wave lower-power wavefront for incident on the active reflect-arrays,

wherein the active reflect-array antenna system comprises a plurality of individual semiconductor wafers arranged together on a surface, each wafer configured to receive, amplify and retransmit.

2. A surface-heating system comprising:

an active reflect-array antenna system to provide a collimated high-power wavefront at a millimeter-wave frequency in a direction of a surface to heat the surface within a surface depth by amplifying and reflecting a spatially-fed millimeter-wave lower-power wavefront; and

a low-power feed to provide the spatially-fed millimeter-wave lower-power wavefront for incident on the active reflect-array,

wherein the active reflect-array antenna system comprises a plurality of individual semiconductor wafers arranged together on a surface, wherein each semiconductor wafer comprises:

a receive antenna to receive signals of the spatially-fed millimeter-wave lower-power wavefront;

a set of power amplifiers coupled to the receive antenna to amplify the received signals; and

a transmit antennae to transmit amplified millimeter-wave signals,

wherein the amplified millimeter-wave signals transmitted by the transmit antennas of each semiconductor wafer spatially combine to generate the collimated high-power wavefront.

3. The system of claim 2 wherein the plurality of semiconductor wafers is arranged in a substantially parabolic shape.

4. The system of claim 2 further comprising a frequency generator to generate the millimeter-wave frequency and provide the millimeter-wave frequency to the low-power feed,

wherein the frequency generator and the active reflect-array antenna system are part of a wavefront-generating subsystem, the system further comprising a thermal-sensing subsystem to measure a surface temperature and generate a control signal for the wavefront-generating subsystem to control the surface temperature.

5. The system of claim 4 wherein the active reflect-array antenna system generates a continuous-wave wavefront, and wherein the antenna system changes a transmit power level of the wavefront in response to the control signal from the thermal-sensing subsystem to control the surface temperature.

6. The system of claim 4 wherein the active reflect-array antenna system generates a pulsed high-power wavefront, and wherein the antenna system reduces one of either a pulse-repetition-rate or a pulse-duration time of the high-power wavefront in response to the control signal to control the surface temperature.

7. The system of claim 2 further comprising a housing having a cavity for placement of a food item, and

wherein the active reflect-array antenna system is one of a plurality of active reflect-array antenna systems positioned within the cavity to direct a plurality of high-power millimeter-wave wavefronts within the cavity to heat a surface of the food item.

8. The system of claim 7 further comprising a microwave amplifier and associated antenna to direct microwave energy within the cavity to heat the food item below the surface.

9. The system of claim 2 wherein the low-power feed comprises a passive reflector to reflect a millimeter-wave frequency signal from a feed and provide the lower-power wavefront for incident on the active reflect-array antenna system.

10. The system of claim 2 wherein the plurality of semiconductor wafers is arranged on a substantially flat surface.

11. The system of claim 2 further comprising

a low-voltage, high-current power supply to generate current for the active reflect-array antenna system and a frequency generator; and

a cooling subsystem to cool the active reflect-array antenna system and the power supply,

wherein the cooling system comprises one of either a thermo-electric-cooling (TEC) element, a phase change fluid, or coolant.

12. The system of claim 4 wherein the frequency generator is configured to generate a plurality of differing millimeter-wave frequencies,

wherein the active reflect-array antenna system provides the high-power wavefront comprising the differing millimeter-wave frequencies, and

wherein the system further comprises a system controller to control a frequency and power level of the wavefront to selectively heat layers of the surface.

13. The system of claim 12 wherein the high-power wavefront is time-multiplexed with differing millimeter-wave frequencies.

14. A surface-heating system comprising:

an active reflect-array antenna system to provide a collimated high-power wavefront at a millimeter-wave frequency in a direction of a surface to heat the surface within a surface depth by amplifying and reflecting a spatially-fed millimeter-wave lower-power wavefront; and

a low-power feed to provide the spatially-fed millimeter-wave lower-power wavefront for incident on the active reflect-array,

wherein the active reflect-array antenna system is a first active reflect-array antenna system and the low-power feed is a second active reflect-array antenna system,

wherein the low-power feed amplifies and reflects millimeter-wave signals received from a source located within of the first active reflect-array antenna system, the low-power feed comprising:

one or more receive antennas to receive the millimeter-wave signals from the source;

one or more amplifiers to amplify the received millimeter-wave frequency signals; and

one or more transmit antennas to transmit the amplified millimeter-wave signals and generate the lower-power wavefront for incidence on the first active reflect-array antenna system.