# US 7,609,226 B1 · Antenna system with base configuration for passive inter-modulation (PIM) mitigation > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 7,609,226 B1 - Document ID: US7609226B1 - Status: Granted - Kind: B1 - Application number: 11/841,225 - Filed: 2007-08-20 - Granted: 2009-10-27 - Earliest claimed: 2007-08-20 - Assignees: Lockheed Martin Corporation - Inventors: Jonathan P. MacGahan; R. Mark Clark - Web page: https://patentgrep.com/patent/US7609226B1 ## CPC - H01Q 11/08: Helical antennas - H01Q: ANTENNAS, i.e. RADIO AERIALS (radiators or antennas for microwave heating H05B6/72) ## Abstract An antenna system comprises an antenna element, a base plate, and a ground plane. The antenna element is configured to radiate signals, receive signals, or radiate and receive signals. The base plate has a front surface facing the antenna element and a rear surface facing away from the antenna element. The front surface of the base plate has an uncovered area, and the uncovered area of the base plate has no exposed conductive mechanical joints. The ground plane has a front surface facing the antenna element and a rear surface facing away from the antenna element. The antenna system further comprises a capacitive coupling between the base plate and the ground plane formed by an overlap region between the base plate and ground plane. The ground plane is capacitively coupled to the base plate in the overlap region. ## Claims ### Claim 1 An antenna system comprising: an antenna element configured to radiate signals, receive signals, or radiate and receive signals; a base plate having a front surface facing the antenna element and a rear surface facing away from the antenna element, the front surface of the base plate having an uncovered area, the uncovered area of the base plate having no exposed conductive mechanical joints, wherein the uncovered area of the base plate is planar having no protrusions; a ground plane having a front surface facing the antenna element and a rear surface facing away from the antenna element, the front surface of the ground plane having an uncovered area, wherein the uncovered area of the ground plane is planar having no protrusions; and a capacitive coupling between the base plate and the ground plane formed by an overlap region between the base plate and ground plane, the ground plane capacitively coupled to the base plate in the overlap region. ### Claim 2 (depends on 1) A system of claim 1, wherein the uncovered area of the ground plane has no exposed conductive mechanical joints. ### Claim 3 (depends on 1) A system of claim 1, wherein a capacitance created by the base plate and the ground plane within the overlap region is greater than a capacitance created by the base plate and the ground plane outside the overlap region. ### Claim 4 (depends on 1) A system of claim 1, wherein the capacitive coupling comprises a layer of dielectric material disposed between the base plate and ground plane in the overlap region. ### Claim 5 (depends on 1) A system of claim 1 further comprising mechanical joints formed by fasteners, clamping arrangements, bonding or a combination thereof. ### Claim 6 (depends on 1) A system of claim 1 further comprising non-conductive mechanical joints. ### Claim 7 (depends on 6) A system of claim 6, wherein at least some of the non-conductive mechanical joints are viewable from a front side of the antenna system. ### Claim 8 (depends on 1) A system of claim 1 further comprising conductive mechanical joints. ### Claim 9 (depends on 1) A system of claim 1 further comprising a base, a clamp ring and mechanical joints, wherein some of the mechanical joints are used to attach the clamp ring and the ground plane together, some of the mechanical joints are used to attach the base plate and the clamp ring together, and some of the mechanical joints are used to attach the base and the base plate together. ### Claim 10 (depends on 1) A system of claim 1, wherein the capacitance created by the base plate and the ground plane within the overlap region is greater than 100 times the capacitance created by the base plate and the ground plane outside the overlap region. ### Claim 11 (depends on 1) A system of claim 1, wherein the base plate, the ground plane and the capacitive coupling are configured to reduce a radio frequency (RF) surface current level at the rear surface of the ground plane. ### Claim 12 (depends on 1) A system of claim 1 further comprising mechanical joints, wherein the base plate, the ground plane, the capacitive coupling, and the mechanical joints are configured to reduce passive inter-modulation. ### Claim 13 (depends on 1) A system of claim 1, wherein the antenna element is a helix antenna element, a quadri-filar antenna element, a monopole antenna element, a sleeve monopole antenna element, a patch antenna element, a slot antenna element, a spiral antenna element, a dipole antenna element, or a plurality of any of the aforementioned antenna elements. ### Claim 14 (depends on 1) A system of claim 1 further comprising: ground plane inserts, a clamp ring, mechanical joints, and a coaxial connector. ### Claim 15 An antenna system comprising: an antenna element configured to radiate signals, receive signals, or radiate and receive signals; a base plate having a front surface facing the antenna element and a rear surface facing away from the antenna element, the front surface of the base plate having an uncovered area, wherein the uncovered area of the base plate is planar having no protrusions; a ground plane having a front surface facing the antenna element and a rear surface facing away from the antenna element, the front surface of the ground plane having an uncovered area, wherein the uncovered area of the ground plane is planar having no protrusions; a capacitive coupling between the base plate and the ground plane formed by an overlap region between the base plate and ground plane, the ground plane capacitively coupled to the base plate in the overlap region, a capacitance created by the base plate and the ground plane within the overlap region being greater than a capacitance created by the base plate and the ground plane outside the overlap region; and mechanical joints mounted from a rear side of the antenna system, the mechanical joints not viewable from a front side of the antenna system. ### Claim 16 (depends on 15) A system of claim 15, wherein the capacitive coupling comprises a layer of dielectric material disposed between the base plate and ground plane in the overlap region. ### Claim 17 (depends on 15) A system of claim 15 further comprising mechanical joints formed by fasteners, clamping arrangements, bonding or a combination thereof. ### Claim 18 (depends on 15) A system of claim 15 further comprising non-conductive mechanical joints. ### Claim 19 (depends on 18) A system of claim 18, wherein at least some of the non-conductive mechanical joints are viewable from a front side of the antenna system. ### Claim 20 (depends on 15) A system of claim 15, wherein the mechanical joints are conductive. ### Claim 21 (depends on 15) A system of claim 15 further comprising a base and a clamp ring, wherein some of the mechanical joints are used to attach the clamp ring and the ground plane together, some of the mechanical joints are used to attach the base plate and the clamp ring together, and some of the mechanical joints are used to attach the base and the base plate together. ### Claim 22 (depends on 15) A system of claim 15, wherein the base plate, the ground plane, the capacitive coupling, and the mechanical joints are configured to reduce passive inter-modulation.