DETAILED ACTION
Notice of Pre-AIA or AIA Status
The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA .
Claim Objections
Claim 19 is objected to because of the following informalities: it recites "an output frequency of the subharmonic tag. "; however, it should recite "an output frequency of the subharmonic tag;". Appropriate correction is required.
Claim Rejections - 35 USC § 103
The following is a quotation of 35 U.S.C. 103 which forms the basis for all obviousness rejections set forth in this Office action:
A patent for a claimed invention may not be obtained, notwithstanding that the claimed invention is not identically disclosed as set forth in section 102, if the differences between the claimed invention and the prior art are such that the claimed invention as a whole would have been obvious before the effective filing date of the claimed invention to a person having ordinary skill in the art to which the claimed invention pertains. Patentability shall not be negated by the manner in which the invention was made.
Claim(s) 1-4 and 6-22 is/are rejected under 35 U.S.C. 103 as being unpatentable over Cassella (US 2021/0318178 A1) in view of Everett (US 5,317,330).
Regarding claim 1, Cassella discloses a subharmonic tag (Cassella discloses a subharmonic tag ("SubHT"): a chip-less, battery-less passive tag that generates and transmits a subharmonic output signal in response to an interrogation signal (Abstract; [0005], [0049], [0060]).) comprising:
a set of lumped components coupled to the antenna, the lumped components having a frequency-dependent input impedance (Cassella's SubHT is disclosed as a network formed by an unbiased variable capacitor (varactor) together with a set of lumped passive electrical elements acting as a stabilization network ([0061]; see also [0086], [0091] listing inductors and capacitors). This is the claimed set of lumped components having a frequency-dependent input impedance.), wherein the frequency-dependent input impedance of the lumped components causes the coupled antenna and lumped components to resonate at both an input frequency of the subharmonic tag and at an output frequency of the subharmonic tag (Cassella teaches that the passive lumped network sets the impedances seen at both f.sub.in and f.sub.out ([0062]); that the components are selected by satisfying resonant conditions that maximize varactor voltage at f.sub.in and minimize the impedance seen at f.sub.out ([0086]); and, concretely, that the circuit parameters were chosen to "resonate and minimize the impedances seen by the adopted variable capacitor at both 886 MHz and 443 MHz" ([0091]) — i.e., resonance at the input frequency and at the output frequency (f.sub.out= f.sub.in/2, [0060], [0062]).).
However, Cassella does not expressly disclose a single antenna having a reactive input impedance.
Everett supplies the single antenna having a reactive input impedance: Everett discloses a passive RF tag employing a single antenna — an inductor-coil antenna (thus having a reactive input impedance) that serves as both the transmit and receive antenna (FIG. 3, col 2 ln 60–64 "transmit and receive antenna 36"; claims 2–3) — in which lumped capacitors form a parallel resonance at the receive (input) frequency and, in combination, a series resonance at the transmit (output) frequency, the transmit frequency differing from the receive frequency (col 2 ln 5–28; FIG. 3 description), such that in the FIG. 3 embodiment the single antenna transmits at a frequency lower than the frequency it receives — the same input-to-lower-output relationship as a subharmonic tag, with the worked example transmitting at 87.5 kHz from a 175 kHz received signal (i.e., exactly half) — the single antenna thereby presenting a reactive input impedance and, by virtue of its lumped components, resonating at both frequencies to meet the claimed elements once combined with the subharmonic-tag teaching of Cassella; and Everett expressly states the benefits of using this single antenna in place of two antennas, namely that it enables "simultaneous transmit and receive operations...through the same antenna circuit" (col 2 ln 5–28), "provides both a cost reduction and a size reduction," and, by using one antenna, "prevents the problem of the receive antenna and transmit antenna talking to each other" (col 3 ln 58–65).
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date to modify the two-antenna subharmonic tag of Cassella by substituting the single dual-resonant antenna circuit of Everett for its two separate antennas — that is, to have one antenna, made resonant at both f.sub.in and f.sub.out by the associated lumped components, both receive the interrogation signal and radiate the subharmonic output. This is the combination of a known device (a passive subharmonic frequency-dividing tag) with a known technique (a single antenna rendered resonant at both a receive frequency and a differing transmit frequency by reactive lumped components) to yield the predictable result of a single-antenna subharmonic tag. A person of ordinary skill in the art would have been motivated to make this substitution to obtain the size reduction and cost reduction expressly taught by the Everett — objectives independently emphasized throughout the SubHT field (miniaturization for high spatial resolution) — and to avoid the two antennas interfering with one another, a concern directly analogous to the self-interference/isolation motivations recited in Applicant's own background ([0003], [0006]). A reasonable expectation of success exists because both references are passive tags that receive at one frequency and re-radiate at a different frequency and both already rely on reactive lumped-element networks to establish frequency-specific resonances; nothing more than routine circuit design is required to co-locate the two resonances on one antenna.
Regarding claim 2, Cassella in view of Everett discloses the subharmonic tag of claim 1, wherein the single antenna is an electrically small antenna (Cassella teaches that the SubHT antenna can be a monolithic integrated antenna "with gains lower than −20 dB (i.e., maximum antenna size less than 1 cm)" ([0058]) for a highly miniaturized (<1 cm²) UHF tag ([0057]). A maximum antenna dimension under 1 cm, together with the accompanying sub −20 dB gain, reflects the small electrical size and low radiation efficiency characteristic of an electrically small antenna. It would have been obvious to one of ordinary skill in the art before the effective filing date to configure the single antenna of the claim 1 combination as an electrically small antenna, as expressly taught by Cassella, in order to achieve the compact, miniaturized (<1 cm²), mass-producible tag that Cassella identifies as a goal ([0056]–[0058]) — an objective furthered by the single-antenna configuration of claim 1. This yields the predictable result of a miniaturized single-antenna subharmonic tag, with a reasonable expectation of success.).
Regarding claim 3, Cassella in view of Everett discloses the subharmonic tag of claim 1, wherein the single antenna includes one or more of a resonant antenna, a dipole, a monopole, a loop, a short dipole, a small loop, a planar square loop, a microstrip, a dielectrically loaded patch, an aperture antenna, or combinations thereof (Everett's single antenna is an inductor coil antenna (Everett, claims 2–3, 5; FIG. 3), which is among the recited alternatives ("a loop"). The single antenna of the claim 1 combination, supplied by Everett, is therefore a loop antenna as claimed.It would have been obvious to one of ordinary skill in the art before the effective filing date to implement the single antenna of the claim 1 combination as the loop (coil) antenna of Everett, as this is the very single antenna structure relied upon in the claim 1 combination and merely uses a known, conventional antenna type to obtain the predictable result of receiving the interrogation signal and radiating the subharmonic output from one antenna, with a reasonable expectation of success.).
Regarding claim 4, Cassella in view of Everett discloses the subharmonic tag of claim 1, wherein the subharmonic tag is formed on a substrate (Cassella teaches that the SubHT is formed by off-the-shelf lumped components assembled on a printed substrate ([0004], [0049], [0060]), and specifically that the SubHT prototype was "designed and assembled on a printed circuit board (PCB) made of FR-4" ([0086]). It would have been obvious to one of ordinary skill in the art before the effective filing date to form the subharmonic tag of the claim 1 combination on a substrate, as expressly taught by Cassella, to obtain a printable, low-cost, mass-producible tag ([0004], [0005], [0045]), yielding the predictable result of a subharmonic tag assembled on a substrate, with a reasonable expectation of success.).
Regarding claim 6, Cassella in view of Everett discloses the subharmonic tag of claim 4, wherein the substrate is a PCB (Cassella teaches that the SubHT prototype was "designed and assembled on a printed circuit board (PCB) made of FR-4" ([0086]). It would have been obvious to one of ordinary skill in the art before the effective filing date to form the subharmonic tag of the claim 4 combination on a PCB, as expressly taught by Cassella, to obtain a low-cost, mass-producible tag assembled from off-the-shelf lumped components ([0004], [0005], [0086]), yielding the predictable result of a subharmonic tag formed on a PCB substrate, with a reasonable expectation of success.).
Regarding claim 7, Cassella in view of Everett discloses the subharmonic tag of claim 1, wherein the subharmonic tag is formed in an integrated chip (Cassella teaches CMOS compatible components "to ensure the smallest form-factor and a large-scale production existing IC-facilities" ([0005]), and discloses an on-chip UHF SubHT "formed, for example, by an on-chip AlScN ferroelectric varactor, an on-chip AlScN antenna, and a set of AlScN resonators," providing "an on-chip sub-harmonic tag" ([0059]; see also [0056]–[0058], describing monolithic integrated antennas and fabrication "using the same semiconductor fabrication processes used for commercial integrated circuits"). It would have been obvious to one of ordinary skill in the art before the effective filing date to form the subharmonic tag of the claim 1 combination in an integrated chip, as expressly taught by Cassella, to obtain the smallest form-factor and enable large-scale IC-based production ([0005], [0058]–[0059]), yielding the predictable result of a subharmonic tag formed in an integrated chip, with a reasonable expectation of success.).
Regarding claim 8, Cassella in view of Everett discloses the subharmonic tag of claim 1, wherein the output frequency is half of the input frequency (Cassella's subharmonic tag operates by a period-doubling / frequency-division mechanism that generates and radiates an output signal at a frequency f.sub.out that is half of the interrogation frequency f.sub.in (f.sub.in = 2f.sub.out) ([0060], [0062]; Abstract). This is confirmed concretely by the prototype, which is interrogated at f.sub.in = 886 MHz and produces its output at f.sub.out = 443 MHz ([0086], [0091]). It would have been obvious to one of ordinary skill in the art before the effective filing date to configure the subharmonic tag of the claim 1 combination such that the output frequency is half of the input frequency, as this is the express subharmonic operation taught by Cassella ([0060], [0062]), yielding the predictable result of a tag whose output is at half the interrogation frequency, with a reasonable expectation of success. Configuring the tag for f.sub.out = f.sub.in/2 also furthers the self-interference immunity and reduced path-loss benefits that Cassella attributes to this subharmonic (2:1) operation ([0006], [0060], [0063]).).
Regarding claim 9, Cassella in view of Everett discloses the subharmonic tag of claim 1, wherein the output frequency is 445 MHz and the input frequency is 890 Mhz (Cassella discloses a subharmonic tag operating with an input (interrogation) frequency of 886 MHz and an output frequency of 443 MHz ([0086], [0091]) — i.e., f.sub.out = f.sub.in/2 — values that lie immediately adjacent to the claimed 890 MHz / 445 MHz and differ from them by less than one-half of one percent. Cassella further teaches that the interrogation frequency is a selectable design parameter: the SubHT lumped components "are selected to minimize P.sub.th given a desired f.sub.in value" ([0062]), the tag is designed for operation in the UHF band ([0056]–[0058]), and Cassella expressly operates its tags at a range of chosen f.sub.in values (e.g., f.sub.in swept/selected across 865–880 MHz in a related embodiment, [0095]). Where, as here, the claimed values are close to or encompassed by values disclosed in the prior art, a prima facie case of obviousness exists absent a showing that the claimed values are critical. See MPEP 2144.05(I). It would therefore have been obvious to one of ordinary skill in the art before the effective filing date to operate the subharmonic tag of the claim 1 combination at an input frequency of 890 MHz with a corresponding output frequency of 445 MHz, as this is a minor, routine selection of the interrogation frequency within the same UHF band and immediately adjacent to the 886 MHz / 443 MHz values Cassella expressly discloses, achieved simply by selecting the tag's lumped-component values for the desired f.sub.in as Cassella teaches ([0062]). This yields the predictable result of subharmonic (2:1) operation at 890 MHz / 445 MHz, with a reasonable expectation of success. Applicant has not identified any criticality or unexpected result attributable to 890 MHz / 445 MHz as distinguished from Cassella's 886 MHz / 443 MHz.).
Regarding claim 10, Cassella in view of Everett discloses the subharmonic tag of claim 1, wherein the lumped components form a one-port parametric frequency divider (PFD) (Cassella discloses that its lumped components form a parametric frequency divider (PFD): the SubHT circuitry is formed by an unbiased variable capacitor (varactor) and a set of lumped passive electrical elements ([0061], [0086], [0091]) that operate as a solid-state parametric frequency divider ([0024], [0052]) to divide the interrogation frequency by two (f.sub.out = f.sub.in/2) through a period-doubling mechanism ([0060], [0062]). Cassella thus teaches lumped components forming a PFD. Cassella discloses this PFD as a two-port network coupled to two separate antennas ([0061]). However, in the claim 1 combination, Everett's single antenna is substituted for Cassella's two antennas, such that the PFD formed by the lumped components is coupled to a single antenna at a single port — i.e., a one-port PFD. Everett teaches the corresponding single-port network topology, in which one antenna is coupled to lumped components establishing both a parallel resonance (for reception at the input frequency) and a series resonance (for transmission at the output frequency) presented at that single antenna port (Everett, col 2 ln 5–28; FIG. 3). It would have been obvious to one of ordinary skill in the art before the effective filing date to configure the lumped-component PFD of Cassella as a one-port PFD in the claim 1 combination. The one-port configuration is the direct and predictable consequence of the single-antenna substitution already established in claim 1: coupling the PFD to a single antenna (per Everett) rather than to two separate antennas necessarily reduces the network to a single port presented to that antenna. The skilled artisan would have been motivated to do so for the same reasons set forth for claim 1 — the size reduction, cost reduction, and avoidance of two antennas interfering with one another taught by Everett — yielding the predictable result of a one-port parametric frequency divider, with a reasonable expectation of success.).
Regarding claim 11, Cassella in view of Everett discloses the subharmonic tag of claim 10, wherein the lumped components forming the PFD further comprise: a capacitive component; an inductive component coupled in series to the capacitive component; and an output component connected in parallel to an input component to form a frequency-dependent portion of the PFD, the frequency-dependent portion of the PFD coupled in series to the capacitive component and the inductive component (Cassella discloses a capacitive component and a series inductive component. The PFD is formed by an unbiased variable capacitor (varactor) — the capacitive component — and Cassella expressly teaches "an additional inductor (L.sub.3)... in series to the adopted nonlinear reactance" so that the input impedance can "resonate at the corresponding frequencies" f.sub.in and f.sub.out ([0064]; see also [0061], [0086]). L.sub.3 is thus an inductive component coupled in series to the capacitive component (varactor). Cassella further discloses a frequency-dependent portion. Cassella's PFD includes reactive (inductor-and-capacitor) sub-networks that set the impedances seen by the varactor at both f.sub.in and f.sub.out and prevent energy at one frequency from flowing toward the undesired termination ([0062], [0064], [0086]). These sub-networks comprise capacitive and inductive elements that establish the frequency-dependent resonances required by the tag. To the extent Cassella does not expressly recite the specific interconnection claimed — a parallel combination of an output component and an input component, that parallel portion coupled in series with the capacitive and inductive branch — Everett teaches this arrangement. In Everett's single-antenna tag, a parallel-resonant reactive portion (antenna 36 in parallel with capacitor 38, resonant at the receive/input frequency) is coupled in series with a further reactive element (capacitor 40) to establish a second, series resonance at the transmit/output frequency (Everett, FIG. 3; col 2 ln 5–28). Everett thus discloses a frequency-dependent portion in which reactive components are connected in parallel to establish one resonance and that parallel portion is coupled in series with a further reactive element to establish a second resonance, in a single-antenna passive tag operating at two frequencies. It would have been obvious to one of ordinary skill in the art before the effective filing date to arrange the lumped components of the Cassella/Everett one-port PFD (claim 10) in the recited configuration — a capacitive component (varactor) in series with an inductive component, that branch coupled in series to a parallel output/input reactive portion. Cassella expressly directs the skilled artisan to select and arrange the lumped components so that the network resonates and sets the varactor's impedances at both f.sub.in and f.sub.out ([0062], [0064]); arranging the reactive elements as a series capacitive-inductive branch coupled to the parallel-connected output and input components is a conventional and predictable way to establish the two required resonances — a parallel branch resonant at one frequency and a series branch resonant at the other — as directly taught by Everett's single-antenna dual-resonance network (FIG. 3). The skilled artisan would have been motivated to adopt this arrangement to achieve the two-frequency resonance Cassella requires while using the single-antenna, one-port configuration of claims 1 and 10, yielding the predictable result of a one-port PFD resonant at both the input and output frequencies, with a reasonable expectation of success.).
Regarding claim 12, Cassella in view of Everett discloses the subharmonic tag of claim 11, wherein the capacitive component includes one or more of a capacitor or a varactor (Cassella discloses that the capacitive component is a varactor. As set forth for claim 11, the capacitive component of the PFD is Cassella's unbiased variable capacitor — expressly a "solid-state varactor" ([0028]; see also [0061], [0086], [0091], identifying the varactor (e.g., Skyworks SMV1430)). Cassella therefore discloses a varactor as the capacitive component. It would have been obvious to one of ordinary skill in the art before the effective filing date to implement the capacitive component of the claim 11 combination as a varactor, as expressly taught by Cassella ([0028], [0061]), because the varactor's voltage-variable capacitance provides the nonlinear reactance modulation that drives the tag's parametric frequency division ([0062]). This yields the predictable result of a PFD whose capacitive component is a varactor, with a reasonable expectation of success.).
Regarding claim 13, Cassella in view of Everett discloses the subharmonic tag of claim 11, wherein the inductive component includes an inductor (As set forth for claim 11, the inductive component of the PFD is Cassella's "additional inductor (L.sub.3)... in series to the adopted nonlinear reactance" ([0064]); Cassella's prototype likewise employs discrete inductors (e.g., L.sub.1, L.sub.2, L.sub.3) as the lumped inductive components ([0086], [0091]). The inductive component is therefore an inductor. It would have been obvious to one of ordinary skill in the art before the effective filing date to implement the inductive component of the claim 11 combination as an inductor, as expressly taught by Cassella ([0064], [0086]), yielding the predictable result of a PFD whose inductive component is an inductor, with a reasonable expectation of success.).
Regarding claim 14, Cassella in view of Everett discloses the subharmonic tag of claim 11, wherein each of the input component and the output component includes one or more of a capacitor, a varactor, an inductor, a MEMS resonator, a crystal resonator, a ceramic resonator, an inductive sensor, a capacitive sensor, or combinations thereof (As set forth for claim 11, the frequency-dependent portion of the PFD is formed by an output component connected in parallel to an input component. In the Cassella/Everett combination, these components are reactive lumped elements — capacitors and/or inductors. Cassella teaches that the PFD's port-side networks are formed of lumped inductors and capacitors (e.g., C.sub.1, C.sub.2, L.sub.1, L.sub.2) that establish the resonances at f.sub.in and f.sub.out ([0064], [0086], [0091]), and Everett likewise forms its parallel-resonant input portion and series-resonant output portion from a coil (inductor) and capacitors (Everett, FIG. 3; claims 2–7). Each of the input component and the output component is therefore one or more of a capacitor, a varactor, or an inductor, as recited. It would have been obvious to one of ordinary skill in the art before the effective filing date to implement each of the input component and the output component of the claim 11 combination as a capacitor and/or an inductor, as taught by Cassella ([0064], [0086]) and Everett (FIG. 3), because these conventional reactive elements are what establish the required input- and output-frequency resonances in the PFD network. This yields the predictable result of input and output components formed of the recited reactive elements, with a reasonable expectation of success.).
Regarding claim 15, Cassella in view of Everett discloses the subharmonic tag of claim 14, wherein the output component includes one or more of a capacitor or a varactor (As set forth for claims 11 and 14, the frequency-dependent portion of the PFD includes an output component that establishes the output-frequency resonance. In the Cassella/Everett combination, this output component is a capacitor: Cassella forms its output-side resonant network from lumped capacitors and inductors (e.g., C.sub.1/C.sub.2, L.sub.1/L.sub.2) that set the impedance seen at f.sub.out ([0064], [0086], [0091]), and Everett's output (series-resonant) portion is likewise established by a capacitor (Everett, FIG. 3, capacitor 40; claims 3–4). The output component is therefore a capacitor as recited (and, in the alternative, may be a varactor, a variable capacitor being expressly used in the same network per Cassella [0061], [0086]). It would have been obvious to one of ordinary skill in the art before the effective filing date to implement the output component of the claim 14 combination as a capacitor (or varactor), as taught by Cassella ([0064], [0086]) and Everett (FIG. 3), because a capacitor is a conventional reactive element for establishing the output-frequency resonance in the PFD network. This yields the predictable result of an output component comprising a capacitor or varactor, with a reasonable expectation of success.).
Regarding claim 16, Cassella in view of Everett discloses the subharmonic tag of claim 14, wherein the input component includes an inductor (As set forth for claims 11 and 14, the frequency-dependent portion of the PFD includes an input component that establishes the input-frequency resonance. In the Cassella/Everett combination, this input component is an inductor: Cassella forms its input-side resonant network from lumped inductors (e.g., L.sub.1) together with capacitors to set the impedance seen at f.sub.in ([0064], [0086], [0091]), and Everett's input (parallel-resonant) portion is likewise established by an inductor — its inductor-coil antenna 36 in parallel with a capacitor, resonant at the receive/input frequency (Everett, FIG. 3; claims 2, 5). The input component is therefore an inductor as recited. It would have been obvious to one of ordinary skill in the art before the effective filing date to implement the input component of the claim 14 combination as an inductor, as taught by Cassella ([0064], [0086]) and Everett (FIG. 3), because an inductor is a conventional reactive element for establishing the input-frequency resonance in the PFD network. This yields the predictable result of an input component comprising an inductor, with a reasonable expectation of success.).
Regarding claim 17, Cassella in view of Everett discloses the subharmonic tag of claim 11, wherein the output component causes the coupled antenna and PFD to resonate at the output frequency of the subharmonic tag (As set forth for claim 11, the frequency-dependent portion of the PFD includes an output component. Cassella teaches that this output-side reactive network establishes the resonance at the output frequency f.sub.out: the lumped components are selected so that the circuit resonates and minimizes the impedance seen by the varactor at f.sub.out ([0062], [0064], [0086]), and Cassella expressly chose its circuit parameters to "resonate...at both 886 MHz and 443 MHz," 443 MHz being f.sub.out ([0091]). Everett similarly teaches that its output component (the series-resonant reactive element) causes the single antenna and its network to be resonant at the transmit/output frequency (Everett, FIG. 3; col 2 ln 5–28). In the claim 1/claim 10 combination, in which the PFD is coupled to the single antenna, the output component thus causes the coupled antenna and PFD to resonate at the output frequency. It would have been obvious to one of ordinary skill in the art before the effective filing date to configure the output component of the claim 11 combination to cause the coupled antenna and PFD to resonate at the output frequency, as expressly taught by Cassella ([0062], [0064], [0091]) and Everett (FIG. 3), because establishing the output-frequency resonance is the recognized function of that output-side reactive component and is required for the tag to radiate its subharmonic output efficiently. This yields the predictable result of a coupled antenna and PFD resonant at the output frequency, with a reasonable expectation of success.).
Regarding claim 18, Cassella in view of Everett discloses the subharmonic tag of claim 11, wherein the input component causes the coupled antenna and PFD to resonate at the input frequency of the subharmonic tag (As set forth for claim 11, the frequency-dependent portion of the PFD includes an input component. Cassella teaches that this input-side reactive network establishes the resonance at the input frequency f.sub.in: the lumped components are selected so that the circuit resonates and sets the impedance seen by the varactor at f.sub.in, maximizing the varactor voltage at f.sub.in ([0062], [0064], [0086]), and Cassella expressly chose its circuit parameters to "resonate...at both 886 MHz and 443 MHz," 886 MHz being f.sub.in ([0091]). Everett similarly teaches that its input component (the parallel-resonant reactive element, i.e., the antenna-coil-and-capacitor combination) causes the single antenna and its network to be resonant at the receive/input frequency (Everett, FIG. 3; col 2 ln 5–28). In the claim 1/claim 10 combination, in which the PFD is coupled to the single antenna, the input component thus causes the coupled antenna and PFD to resonate at the input frequency. It would have been obvious to one of ordinary skill in the art before the effective filing date to configure the input component of the claim 11 combination to cause the coupled antenna and PFD to resonate at the input frequency, as expressly taught by Cassella ([0062], [0064], [0091]) and Everett (FIG. 3), because establishing the input-frequency resonance is the recognized function of that input-side reactive component and is required for the tag to receive the interrogation signal and develop sufficient varactor voltage to trigger frequency division. This yields the predictable result of a coupled antenna and PFD resonant at the input frequency, with a reasonable expectation of success.).
Regarding claim 19, Cassella discloses a method for passive wireless communication (Cassella discloses a chip-less, battery-less passive tag-based wireless sensor node that passively communicates sensed information to an interrogating node without any supplied or harvested DC power (Abstract; [0004], [0049], [0060])) comprising:
providing a subharmonic tag (Cassella discloses providing a subharmonic tag ("SubHT"): a chip-less, battery-less passive tag that generates and transmits a subharmonic output signal in response to an interrogation signal (Abstract; [0005], [0049], [0060]).) comprising:
a set of lumped components coupled to the antenna, the lumped components having a frequency-dependent input impedance (Cassella's SubHT is disclosed as a network formed by an unbiased variable capacitor (varactor) together with a set of lumped passive electrical elements acting as a stabilization network ([0061]; see also [0086], [0091] listing inductors and capacitors); this is the claimed set of lumped components having a frequency-dependent input impedance), wherein the frequency-dependent input impedance of the lumped components causes the coupled antenna and lumped components to resonate at both an input frequency of the subharmonic tag and at an output frequency of the subharmonic tag (Cassella teaches that the passive lumped network sets the impedances seen at both f.sub.in and f.sub.out ([0062]); that the components are selected by satisfying resonant conditions that maximize varactor voltage at f.sub.in and minimize the impedance seen at f.sub.out ([0086]); and, concretely, that the circuit parameters were chosen to "resonate and minimize the impedances seen by the adopted variable capacitor at both 886 MHz and 443 MHz" ([0091]) — i.e., resonance at the input frequency and at the output frequency (f.sub.out= f.sub.in/2, [0060], [0062]).).
receiving, by the antenna of the subharmonic tag, an interrogation signal having the input frequency (Cassella teaches that the tag receives, via its antenna, the interrogation signal transmitted by the interrogating node at the input frequency f.sub.in ([0060], [0062], [0086]).);
resonating, responsive to the interrogation signal, the antenna and the lumped components at the output frequency (Cassella teaches that, when the received input power exceeds the parametric threshold, the interrogation signal drives the varactor-based lumped network through a period-doubling mechanism into a frequency-division regime, the network being resonant at the output frequency f.sub.out = f.sub.in/2 ([0060], [0062], [0091]).); and
transmitting, responsive to the resonating of the antenna and the lumped components at the output frequency, an output signal from the antenna (Cassella teaches that the tag radiates the parametrically generated output signal at f.sub.out from its antenna back to the interrogating node ([0060], [0062])).
However, Cassella does not expressly disclose a single antenna having a reactive input impedance.
Everett supplies the single antenna having a reactive input impedance: Everett discloses a passive RF tag employing a single antenna — an inductor-coil antenna (thus having a reactive input impedance) that serves as both the transmit and receive antenna (FIG. 3, col 2 ln 60–64 "transmit and receive antenna 36"; claims 2–3) — in which lumped capacitors form a parallel resonance at the receive (input) frequency and, in combination, a series resonance at the transmit (output) frequency, the transmit frequency differing from the receive frequency (col 2 ln 5–28; FIG. 3 description), such that in the FIG. 3 embodiment the single antenna transmits at a frequency lower than the frequency it receives — the same input-to-lower-output relationship as a subharmonic tag, with the worked example transmitting at 87.5 kHz from a 175 kHz received signal (i.e., exactly half) — the single antenna thereby presenting a reactive input impedance and, by virtue of its lumped components, resonating at both frequencies to meet the claimed elements once combined with the subharmonic-tag teaching of Cassella; and Everett expressly states the benefits of using this single antenna in place of two antennas, namely that it enables "simultaneous transmit and receive operations...through the same antenna circuit" (col 2 ln 5–28), "provides both a cost reduction and a size reduction," and, by using one antenna, "prevents the problem of the receive antenna and transmit antenna talking to each other" (col 3 ln 58–65).
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date to modify the two-antenna subharmonic tag of Cassella by substituting the single dual-resonant antenna circuit of Everett for its two separate antennas — that is, to have one antenna, made resonant at both f.sub.in and f.sub.out by the associated lumped components, both receive the interrogation signal and radiate the subharmonic output. This is the combination of a known device (a passive subharmonic frequency-dividing tag) with a known technique (a single antenna rendered resonant at both a receive frequency and a differing transmit frequency by reactive lumped components) to yield the predictable result of a single-antenna subharmonic tag. A person of ordinary skill in the art would have been motivated to make this substitution to obtain the size reduction and cost reduction expressly taught by the Everett — objectives independently emphasized throughout the SubHT field (miniaturization for high spatial resolution) — and to avoid the two antennas interfering with one another, a concern directly analogous to the self-interference/isolation motivations recited in Applicant's own background ([0003], [0006]). A reasonable expectation of success exists because both references are passive tags that receive at one frequency and re-radiate at a different frequency and both already rely on reactive lumped-element networks to establish frequency-specific resonances; nothing more than routine circuit design is required to co-locate the two resonances on one antenna.
Regarding claim 20, Cassella in view of Everett discloses the method of claim 19, wherein the lumped components form a one-port parametric frequency divider (PFD), wherein the lumped components forming the PFD include a capacitive component, an inductive component coupled in series to the capacitive component, and an output component connected in parallel to an input component to form a frequency-dependent portion of the PFD, the frequency-dependent portion of the PFD coupled in series to the capacitive component and the inductive component (These are the same limitations addressed in the rejections of claims 10 and 11 above, and are rejected on the same grounds for the same reasons, which are incorporated here. Cassella's varactor-and-lumped-component network operates as a parametric frequency divider ([0024], [0052], [0060]–[0062]), with the varactor as the capacitive component and inductor L.sub.3 in series therewith ([0064]); the single-antenna substitution of claim 19 renders the PFD one-port (Everett, FIG. 3); and Everett teaches the recited frequency-dependent portion — a parallel-resonant reactive portion (antenna 36 with capacitor 38) coupled in series with a further reactive element (capacitor 40) to establish resonances at the input and output frequencies (Everett, FIG. 3; col 2 ln 5–28). It would have been obvious to arrange the lumped components of the claim 19 method in this configuration for the reasons set forth for claims 10 and 11, yielding the predictable result of a passive wireless communication method using a one-port PFD resonant at both the input and output frequencies, with a reasonable expectation of success.).
Regarding claim 21, Cassella in view of Everett discloses the method of claim 20, wherein the output component causes the coupled antenna and PFD to resonate at the output frequency of the subharmonic tag (This is the same limitation addressed in the rejection of claim 17 above, and is rejected on the same grounds for the same reasons, which are incorporated here. Cassella teaches that the output-side reactive network establishes the resonance at the output frequency f.sub.out — the lumped components are selected to resonate and minimize the impedance seen by the varactor at f.sub.out ([0062], [0064], [0086]), Cassella expressly choosing its circuit parameters to "resonate... at both 886 MHz and 443 MHz," 443 MHz being f.sub.out ([0091]) — and Everett likewise teaches that its output (series-resonant) component causes the single antenna and its network to resonate at the transmit/output frequency (Everett, FIG. 3; col 2 ln 5–28). In the single-antenna combination of claims 19–20, the output component thus causes the coupled antenna and PFD to resonate at the output frequency. It would have been obvious to so configure the output component for the reasons set forth for claim 17, yielding the predictable result of a coupled antenna and PFD resonant at the output frequency, with a reasonable expectation of success.).
Regarding claim 22, Cassella in view of Everett discloses the method of claim 20, wherein the input component causes the coupled antenna and PFD to resonate at the input frequency of the subharmonic tag (This is the same limitation addressed in the rejection of claim 18 above, and is rejected on the same grounds for the same reasons, which are incorporated here. Cassella teaches that the input-side reactive network establishes the resonance at the input frequency f.sub.in — the lumped components are selected to resonate and set the impedance seen by the varactor at f.sub.in, maximizing the varactor voltage at f.sub.in ([0062], [0064], [0086]), Cassella expressly choosing its circuit parameters to "resonate... at both 886 MHz and 443 MHz," 886 MHz being f.sub.in ([0091]) — and Everett likewise teaches that its input (parallel-resonant) component, i.e., the antenna-coil-and-capacitor combination, causes the single antenna and its network to resonate at the receive/input frequency (Everett, FIG. 3; col 2 ln 5–28). In the single-antenna combination of claims 19–20, the input component thus causes the coupled antenna and PFD to resonate at the input frequency. It would have been obvious to so configure the input component for the reasons set forth for claim 18, yielding the predictable result of a coupled antenna and PFD resonant at the input frequency, with a reasonable expectation of success.).
Claim(s) 5 is/are rejected under 35 U.S.C. 103 as being unpatentable over Cassella (US 2021/0318178 A1) in view of Everett (US 5,317,330) and Knight (US 2022/0147788 A1).
Regarding claim 5, Cassella in view of Everett discloses the subharmonic tag of claim 4, but does not expressly disclose wherein the substrate is flexible. Specifically, Cassella discloses forming the subharmonic tag on a substrate (as set forth for claim 4), and further teaches that the tag is printable on disposable substrates ([0045]) and contemplates "compact, wearable, and mass producible" tags ([0056]). Cassella's built prototype is assembled on rigid FR-4 ([0086]) and does not expressly state that the substrate is flexible.
Knight discloses a passive UHF RFID tag comprising an antenna, and a lumped antenna matching circuit that includes at least an inductor electrically coupled to the antenna (and may further comprise resistors, inductors, and capacitors), formed on an elongated flexible substrate that provides a dielectric support structure for the antenna and is configured to bend into a curved arc (up to a 45-degree arc angle) without failure (Knight, Abstract; [0031]–[0033], [0036], [0039], [0042]). Knight thus discloses a passive UHF RF tag structurally analogous to the claimed tag — an antenna coupled to a lumped reactive (inductive) network carried on a substrate — in which the substrate is flexible (e.g., a polyimide/Kapton, [0036]).
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date to form the substrate of the Cassella/Everett subharmonic tag (claim 4) as a flexible substrate, as taught by Knight, in order to realize the wearable, conformable, printable tag that Cassella itself contemplates ([0045], [0056]) — a flexible substrate being a conventional and art-recognized means of enabling a passive UHF RF tag bearing an antenna and lumped components to conform to curved or non-planar surfaces, as Knight demonstrates ([0039], [0075]). This amounts to the substitution of one known substrate type (flexible) for another (rigid) in a passive RF tag carrying an antenna and lumped reactive network, to obtain the predictable result of a conformable/wearable subharmonic tag, with a reasonable expectation of success.
Conclusion
The prior art made of record and not relied upon is considered pertinent to applicant's disclosure.
US 5,608,417 - teaches a passive RF transponder tag whose antenna circuit is parallel-resonant at the interrogation (receive) frequency and series-resonant at a different response (transmit) frequency. This reference is pertinent to the subject matter of claim 11, evidencing that lumped-element passive tag networks presenting a parallel resonance at one frequency and a series resonance at a different frequency were known in the art. See Abstract; FIGS. 3a–3b.
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/RAJSHEED O BLACK-CHILDRESS/Examiner, Art Unit 2685
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