# US 9,882,288 B2 · Slotted surface scattering antennas > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,882,288 B2 - Document ID: US9882288B2 - Status: Granted - Kind: B2 - Application number: 14/755,579 - Filed: 2015-06-30 - Published: 2015-12-31 - Granted: 2018-01-30 - Earliest claimed: 2014-05-02 - Assignees: The Invention Science Fund I, LLC - Applicants: Searete LLC - Inventors: Eric J. Black; Brian Mark Deutsch; Alexander Remley Katko; Melroy Machado; Jay Howard McCandless; Yaroslav A. Urzhumov - Web page: https://patentgrep.com/patent/US9882288B2 ## CPC - H01Q 23/00: Antennas with active circuits or circuit elements integrated within them or attached to them - H01H 59/0009: {making use of micromechanics} - H01Q 3/443: {varying the phase velocity along a leaky transmission line (frequency scanning H01Q3/22; non-resonant leaky-waveguide or transmission-line aerials H01Q13/20)} - H01Q 13/206: {Microstrip transmission line antennas} - H01Q 9/0407: {Substantially flat resonant element parallel to ground plane, e.g. patch antenna (dipole H01Q9/285; monopole H01Q9/40)} - H01Q: ANTENNAS, i.e. RADIO AERIALS (radiators or antennas for microwave heating H05B6/72) - H01H: ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES (contact cables H01B7/10; electrolytic self-interrupters H01G9/18; emergency protective circuit arrangements H02H; switching by electronic means without contact-making H03K17/00) ## Abstract Surface scattering antennas with lumped elements provide adjustable radiation fields by adjustably coupling scattering elements along a waveguide. In some approaches, the scattering elements include slots in an upper surface of the waveguide, and the lumped elements are configured to span the slots provide adjustable loading. In some approaches, the scattering elements are adjusted by adjusting bias voltages for the lumped elements. In some approaches, the lumped elements include diodes or transistors. ## Claims ### Claim 1 An antenna, comprising: a waveguide; a plurality of subwavelength radiative elements coupled to the waveguide; and a plurality of lumped element circuits directly coupled to the subwavelength radiative elements and configured to adjust radiation characteristics of the subwavelength radiative elements; wherein the waveguide includes a bounding surface, and the plurality of subwavelength radiative elements includes a plurality of unit cells each containing a slot in the bounding surface; wherein the waveguide defines a propagation direction, and the subwavelength radiative elements have inter-element spacings along the propagation direction that are substantially less than a free-space wavelength corresponding to an operating frequency band of the antenna; and wherein the inter-element spacings are less than or equal to one-third of the free-space wavelength. ### Claim 2 (depends on 1) The antenna of claim 1, wherein the waveguide is a stripline waveguide. ### Claim 3 (depends on 2) The antenna of claim 2, wherein the plurality of subwavelength radiative elements includes: a first plurality of subwavelength radiative elements coupled to a left edge of the stripline waveguide; and a second plurality of subwavelength radiative elements coupled to a right edge of the stripline waveguide. ### Claim 4 (depends on 3) The antenna of claim 3, wherein the first plurality and the second plurality are positioned at equal positions along a length of the stripline waveguide. ### Claim 5 (depends on 3) The antenna of claim 3, wherein the first plurality and the second plurality are positioned at first and second staggered positions along a length of the stripline waveguide. ### Claim 6 (depends on 5) The antenna of claim 5, wherein the second staggered positions are midpoints between adjacent first positions. ### Claim 7 (depends on 1) The antenna of claim 1, wherein the inter-elements spacings are less than or equal to one-fourth of the free-space wavelength. ### Claim 8 (depends on 1) The antenna of claim 1, wherein the inter-elements spacings are less than or equal to one-fifth of the free-space wavelength. ### Claim 9 (depends on 1) The antenna of claim 1, wherein each slot defines a slot width dimension and a slot length dimension, and the slot length dimension is substantially equal to one-half of the free-space wavelength. ### Claim 10 (depends on 9) The antenna of claim 9, wherein the slot length dimension corresponds to a direction perpendicular to the propagation direction. ### Claim 11 (depends on 1) The antenna of claim 1, wherein the lumped circuit elements include, for each of the plurality of unit cells, a three-port element with a first port connected to one side of the slot and a second port connected to another slide of the slot. ### Claim 12 (depends on 11) The antenna of claim 11, further comprising, for each of the plurality of unit cells: a bias voltage line connected to a third port of the three-port element. ### Claim 13 (depends on 11) The antenna of claim 11, wherein each three-port element is a transistor. ### Claim 14 (depends on 1) The antenna of claim 1, wherein the lumped circuit elements include, for each of the plurality of unit cells, a pair of two-port elements connected in series across the slot. ### Claim 15 (depends on 14) The antenna of claim 14, wherein the pair of two-port elements is a diode and a blocking capacitor. ### Claim 16 (depends on 14) The antenna of claim 14, further comprising, for each of the plurality of unit cells: a bias voltage line connected between a node common to the pair of two-port elements. ### Claim 17 (depends on 14) The antenna of claim 14, wherein each pair of two-port elements is a pair of nonlinear variable-impedance devices. ### Claim 18 (depends on 17) The antenna of claim 17, wherein each pair of nonlinear variable-impedance devices is a matched pair of nonlinear variable-impedance devices. ### Claim 19 (depends on 17) The antenna of claim 17, wherein the nonlinear variable-impedance devices include MEMS switched capacitors or MEMS varactors. ### Claim 20 (depends on 14) The antenna of claim 14, wherein the pair of two-port elements is a pair of diodes. ### Claim 21 (depends on 20) The antenna of claim 20, wherein each diode in the pair of diodes has a cathode connected to the slot and an anode connected to the other diode in the pair of diodes. ### Claim 22 (depends on 20) The antenna of claim 20, wherein each diode in the pair of diodes has an anode connected to the slot and a cathode connected to the other diode in the pair of diodes. ### Claim 23 (depends on 20) The antenna of claim 20, wherein the pair of diodes is a pair of varactors. ### Claim 24 (depends on 14) The antenna of claim 14, wherein the pair of two-port elements is a pair of oppositely-oriented two-port elements. ### Claim 25 (depends on 24) The antenna of claim 24, wherein the pair of oppositely-oriented two-port elements is a pair of identical, oppositely-oriented two-port elements. ### Claim 26 (depends on 14) The antenna of claim 14, wherein the pair of two-port elements is configured so that a first 2nd harmonic generated by a first element in the pair of two-port elements is substantially cancelled by a second 2nd harmonic generated by a second element in the pair of two-port elements. ### Claim 27 (depends on 1) The antenna of claim 1, wherein the lumped circuit elements include, for each of the plurality of unit cells, a first lumped element connected at or near an upper end of the slot and a second lumped element connected at or near a lower end of the slot. ### Claim 28 (depends on 27) The antenna of claim 27, wherein the lumped circuit elements further include one or more additional lumped elements connected at one or more additional positions along the slot between the first lumped element and the second lumped element. ### Claim 29 (depends on 27) The antenna of claim 27, wherein: the radiation characteristics of the subwavelength radiative elements include, for each unit cell, a scattering parameter having a frequency variation at an operating frequency band of the antenna; and positions of the first and second lumped elements are selected to reduce or minimize the frequency variation of the scattering parameter. ### Claim 30 (depends on 27) The antenna of claim 27, wherein: the radiation characteristics of the subwavelength radiative elements include, for each unit cell, a scattering parameter having a frequency variation at an operating frequency band of the antenna; and the first and second lumped elements have respective first and second impedances that vary with frequency, the first and second variable impedances being selected to reduce or minimize the frequency variation of the scattering parameter. ### Claim 31 (depends on 27) The antenna of claim 27, wherein: the radiation characteristics of the subwavelength radiative elements include, for each unit cell, a total scattering parameter that includes contributions from a first scattering parameter corresponding to the first lumped element and a second scattering parameter corresponding to the second lumped element; wherein a frequency variation of the first scattering parameter is substantially complementary to a frequency variation of the second scattering parameter. ### Claim 32 (depends on 27) The antenna of claim 27, wherein the first lumped element is a first varactor and the second lumped element is a second varactor. ### Claim 33 (depends on 27) The antenna of claim 27, wherein the first lumped element is a first transistor and the second lumped element is a second transistor. ### Claim 34 (depends on 27) The antenna of claim 27, wherein the first lumped element is a varactor and the second lumped element is a transistor. ### Claim 35 (depends on 1) The antenna of claim 1, wherein the waveguide is a stripline waveguide, the bounding surface is an upper ground plane of the stripline, and each slot includes an opening sufficient to admit a bias line for the lumped element circuit of that unit cell. ### Claim 36 (depends on 35) The antenna of claim 35, wherein each slot includes narrow first portion that extends from the opening and towards the stripline and a narrow second portion that extends from the opening and away from the stripline. ### Claim 37 (depends on 36) The antenna of claim 36, wherein the opening is a circular antipad enclosing a pad for the bias line. ### Claim 38 (depends on 35) The antenna of claim 35, wherein each slot has a total length equal to about one-half of a free-space wavelength corresponding to an operating frequency band of the antenna, where the total length equals a length of the narrow first portion plus a length of the narrow second portion plus a diameter of the opening. ### Claim 39 (depends on 35) The antenna of claim 35, wherein the stripline waveguide includes a lower ground plane and each bias line extends through both the upper ground plane and the lower ground plane. ### Claim 40 (depends on 39) The antenna of claim 39, further comprising: for each unit cell, a stub choke for the bias line. ### Claim 41 (depends on 40) The antenna of claim 40, wherein each stub choke is configured to provide a high impedance of the bias line at an operating frequency band of the antenna. ### Claim 42 (depends on 40) The antenna of claim 40, wherein each stub choke is positioned on a metal layer positioned below the lower ground plane of the stripline waveguide. ### Claim 43 (depends on 39) The antenna of claim 39, wherein each unit cell includes an arrangement of vias enclosing both the stripline and the slot. ### Claim 44 (depends on 43) The antenna of claim 43, wherein the upper ground plane, the lower ground plane, and the arrangement of vias define a cavity volume for the unit cell. ### Claim 45 (depends on 35) The antenna of claim 35, further comprising: a dielectric layer positioned above the upper ground plane, where each bias line extends through the dielectric layer to connect to the lumped element circuit on the upper surface of the dielectric layer.