(12) INTERNATIONAL APPLICATION PUBLISHED UNDER THE PATENT COOPERATION TREATY (PCT) (19) World Intellectual Property Organization International Bureau (10) International Publication Number (43) International Publication Date WO 2017/081685 Al 18 May 2017 (18.05.2017) P O P C T (51) International Patent Classification: HN, HR, HU, ID, IL, IN, IR, IS, JP, KE, KG, KN, KP, KR, G01S 13/42 (2006.01) KW, KZ, LA, LC, LK, LR, LS, LU, LY, MA, MD, ME, MG, MK, MN, MW, MX, MY, MZ, NA, NG, NI, NO, NZ, (21) International Application Number: OM, PA, PE, PG, PH, PL, PT, QA, RO, RS, RU, RW, SA, PCT/IL2016/05 1213 SC, SD, SE, SG, SK, SL, SM, ST, SV, SY, TH, TJ, TM, (22) International Filing Date: TN, TR, TT, TZ, UA, UG, US, UZ, VC, VN, ZA, ZM, 10 November 2016 (10.1 1.2016) ZW. (25) Filing Language: English (84) Designated States (unless otherwise indicated, for every kind of regional protection available): ARIPO (BW, GH, (26) Publication Language: English GM, KE, LR, LS, MW, MZ, NA, RW, SD, SL, ST, SZ, (30) Priority Data: TZ, UG, ZM, ZW), Eurasian (AM, AZ, BY, KG, KZ, RU, 242588 12 November 2015 (12. 11.2015) IL TJ, TM), European (AL, AT, BE, BG, CH, CY, CZ, DE, DK, EE, ES, FI, FR, GB, GR, HR, HU, IE, IS, IT, LT, LU, (71) Applicant: ISRAEL AEROSPACE INDUSTRIES LTD. LV, MC, MK, MT, NL, NO, PL, PT, RO, RS, SE, SI, SK, [IL/IL]; Ben-Gurion International Airport, 7010000 Lod SM, TR), OAPI (BF, BJ, CF, CG, CI, CM, GA, GN, GQ, (IL). GW, KM, ML, MR, NE, SN, TD, TG). (72) Inventor: COHEN, Moshik; 8 Pinhas Hagin Street, Declarations under Rule 4.17 : 4975 108 Petah Tikva (IL). as to applicant's entitlement to apply for and be granted a (74) Agent: KRAVETZ, Yossi; Reinhold Cohn and Partners, patent (Rule 4.1 7(H)) P.O. Box 13239, 6 113 102 Tel Aviv (IL). of inventorship (Rule 4.17(iv)) (81) Designated States (unless otherwise indicated, for every Published: kind of national protection available): AE, AG, AL, AM, AO, AT, AU, AZ, BA, BB, BG, BH, BN, BR, BW, BY, with international search report (Art. 21(3)) BZ, CA, CH, CL, CN, CO, CR, CU, CZ, DE, DJ, DK, DM, DO, DZ, EC, EE, EG, ES, FI, GB, GD, GE, GH, GM, GT, (54) Title: INTEGRATED ELECTROMAGNETIC SEEKER 00 o (57) Abstract: The presently disclosed subject matter includes an electromagnetic seeker comprising: an antenna having multiple ra o diating elements; the antenna is divided into a plurality of sections each section comprising a group of radiating elements and is dir ectly connected to a respective single power stage configured to provide power to the radiating elements; each section and a respect - o ive single power stage are configured to provide coherent combination of signals transmitted by different antenna sections over the air to thereby enable combination of power from all antenna sections over the air.
INTEGRATED ELECTROMAGNETIC SEEKER FIELD O F T H E INVENTION This invention relates t o electromagnetic seekers BACKG ROU N D An electromagnetic seeker incl udes a tra nsmitter assem bly for tra nsmitting pu lsed radiations and a receiver asse mbly for receiving reflections that su rpasses an adjusta ble detection t hreshold. The electromagnetic seeker also incl udes a t arget reflection detection mod ule for detecting a desired t arget as wel l as esti mators for estimating various t arget parameters and trackers for implementing t arget tracking. GENERAL DESCRI PTION The presently disclosed su bject matte r incl udes a new electromagnetic see ke r mou nta ble on an airborne platform such as a missile o r aircraft and ca pable of pe rforming differe nt operations such as: sea rching for a t arget; detecting the t arget; tracking the target; and homing on the target. In genera l the tra nsmitter assem bly of an electromagnetic see ker tra nsmits an electromagnetic signa l (such as a lase r signa l) towa rds a sea rch vol ume (area desi red to be sea rched for t argets). Signa l portions reflected from a t arget are received by the receiver assem bly and processed by a signa l processing unit in the seeke r. The ability of the see ker t o detect signa l portions reflected from a target depe nd s, inter alia, on the signa l t o noise ratio (SN R) of the signa l portions reflected from the t arget which are received by the seeker. The SN R depends o n va rious parameters some of which are related t o the architectu re and operation of the seeker. One parameter is the power of the signa l tra nsmitted by the tra nsmitter asse mbly. Anothe r parameter is the atte nuation level of
the signals which are transmitted by the transmitter assembly and the attenuation level of the signals received by the receiver assembly. Attenuation of transmitted signals occurs for example, during power combination from different power stages and during passage of the signals through cables and connectors directing the signal towards the antenna for transmission. Attenuation of received signals occurs during passage of the received signal through various seeker components (e.g. antenna, filter, isolator, limiter, cables, comparators, etc.) located between the seeker head and the seeker low noise amplifier. Thus, in order t o improve the efficiency of the seeker it is desirable t o reduce the signal attenuation (radio frequency (RF) losses) caused by the seeker components. The presently disclosed subject matter includes an electromagnetic seeker with a new architecture which enables t o reduce the RF losses and thereby improve the SNR. According t o some examples of the presently disclosed subject matter, there is provided an electromagnetic seeker comprising: an antenna having multiple radiating elements; the antenna is divided into a plurality of sections each section comprising a group of radiating elements and is directly connected t o a respective single power stage configured t o provide power t o the radiating elements; each section and a respective single power stage are configured t o provide coherent combination of signals transmitted by different antenna sections over the air t o thereby enable combination of power from all antenna sections over the air. The seeker according t o the above aspect of the presently disclosed subject matter can optionally comprise one o r more of the features below in any technically possible combination o r permutation:
The seeker further comprises a respective receiving channel directly connected t o each antenna section; the receiving channel is connected further t o a processing unit comprising a digital comparator module configured t o digitally provide mono-pulse signals; Wherein the receiving channel is configured as a single sub-assembly printed on a circuit board as single integrated unit; The seeker is mounted on a single printed circuit board; The seeker according to claim 1 wherein each one of the single power stages is printed on the opposite side of the antenna printed circuit board; The seeker is mounted entirely on a gimbal assembly; and The seeker according t o any one of the preceding claims is a laser seeker. BRIEF DESCRIPTION O F THE DRAWINGS In order t o understand the invention and t o see how it may be carried out in practice, a preferred embodiment will now be described, by way of non-limiting example only, with reference t o the accompanying drawings, in which: Fig. 1 is a functional block diagram schematically illustrating an example of a laser system, in accordance with the presently disclosed subject matter; Fig. 2 is a flowchart illustrating an example of a sequence of operation performed during interception of a single target, in accordance with the presently disclosed subject matter; and Figs. 3 shows a graph demonstrating the SNR as a function of the range between the seeker and target obtained with by a seeker configured according t o the architecture disclosed herein.
DETAILED DESCRIPTION As used herein, the phrase "for example," "such as" and variants thereof describing exemplary implementations of the present invention are exemplary in nature and not limiting. It is appreciated that certain features of the invention, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the invention, which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable sub-combination. While the invention has been shown and described with respect t o particular embodiments, it is not thus limited. Numerous modifications, changes and improvements within the scope of the invention will now occur t o the reader. In embodiments of the invention, fewer, more and/or different stages than those shown in Fig 2. may be executed. In embodiments of the invention multiple stages illustrated in Fig 2. may be executed simultaneously. Fig. 1 illustrates a schematic of the system architecture in accordance with embodiments of the invention. Module/Units in Fig. 1 can be made up of any combination of software and hardware and\or firmware that performs the functions as defined and explained herein. Modules/ Units in Fig. 1 may be centralized in one location or dispersed over more than one location. In other embodiments of the, the system may comprise fewer, more and or different modules than those shown in Fig. 1. Bearing the above in mind, attention is now drawn t o Fig. 1 showing a functional block diagram schematically illustrating an example of an electromagnetic seeker 100, in accordance with the presently disclosed subject matter. Transmitter assembly:
Previously known architectures of transmitter assemblies in electromagnetic seekers include a single transmitter unit comprising numerous power stages (e.g. power transistors) which are combined t o create a single transmission signal. This signal is routed using RF connectors and cables t o the antenna for over the air transmission towards the search volume. Thus, according t o this approach multiple power stages are physically connected t o increase the power output which is delivered t o the antenna. The inter-connections between the numerous power stages in the transmitter unit involve high RF losses which is a first source of signal attenuation. The cables and connectors leading the signal t o the transmitting antenna from the transmitter unit also involve considerable RF loss, which is a second source of signal attenuation. Receiver assembly: Previously known architectures of receiver assemblies in electromagnetic seekers include RF comparator, RF switches and cables which are connected between the antenna and a receiving channel. The comparator, switches and cables are a third source of attenuation occurring after signal reception. In addition, the receiving channel comprises a plurality of sub-assemblies which are inter-connected by cables and connectors. These cables and connector provide a fourth source of attenuation. Fig. 1 shows a functional block diagram of a new seeker architecture disclosed herein. The disclosed architecture helps t o reduce the RF signal loss that is found in the prior art seekers. The proposed architecture addresses all four RF loss sources which were described above. New transmitter assembly: A seeker antenna comprises multiple (e.g. 100 or more) radiating elements which are normally divided into a number of sections, typically 4 quarters. According t o the presently disclosed subject matter, a single power stage is directly connected t o a group of antenna radiating elements. For example, in an antenna divided into 4 sections, in
this case quarters, the radiating elements in each quarter are directly connected t o a single power stage. By connecting the power stage directly t o the antenna and avoiding the inter-connection between different power stages, the first source of signal attenuation is eliminated o r at least considerably reduced. Additionally, the combination of the signals emitted by each power stage is performed by coherent combination over the air (not by cable), which reduces RF loss that normally occurs when physical connections are used. The power stage and the antenna are specifically configured t o ensure that the transmitted signals from all part of the antenna are coherently combined in the air. Furthermore, the single power stage is directly connected t o each group of radiating elements without using any cables and connectors. For example, the power stages can be printed o n the opposite side of the antenna printed circuit board (PCB). This direct connection provides the elimination (or at least reduction) of the second source of signal attenuation. New receiver assembly: According t o the disclosed electromagnetic seeker architecture, the RF comparator is removed and a respective receiving channel is directly connected t o a group of the antenna radiating elements (antenna section). The receiving channel can include for example: low noise amplifiers, RF band pass filter, RF frequency translator. The receiving channel is connected at the other end t o a processing unit. Notably, by connecting the receiving channel directly t o the antenna, the switches which are connected t o the comparator in prior art receiving assemblies are also removed. This allows t o overcome (or at least reduce) the third source of attenuation comparator, occurring after signal reception mentioned above which is caused by the RF switches and connectors.
The functionalities of the comparator are digitally implemented by the processing unit (1) (denoted by way of example in Fig. 1 as Ultrascale FPGA by Xilinx ) which includes an embedded ARM CPU. The processing unit comprises software & logic (4). The processing unit comprises a respective module (digital comparator module) configured t o perform the relevant operations of the comparators. The digital comparator module is configured, inter alia, t o generate and provide the mono-pulse signals (,, ). Additionally, according t o some examples the receiving channel is designed and implemented as a single sub-assembly printed as single integrated unit. For example, this can be accomplished by using CMOS 65 nm technology. This is different than the common approach which divides the receiving channel into a number of sub-assemblies each o n a separate printed board and uses connectors and cables in order t o connect between the different sub-assemblies. This allows overcoming (or at least reducing) the fourth source of attenuation as mentioned above. As mentioned above, prior art transmitter assemblies include a transmitter unit which comprises multiple power stages each providing a respective amount of power. The number of power stages which are used in a transmitter unit is adapted t o provide the required total power for obtaining desired SNR values. Because of power attenuation resulting from the design, cables and connections in the transmitter unit, the actual power which is provided by the combination of power stages is smaller than the mathematical combination of the power values of all the power stages added together. Thus, more power stages are needed in order t o obtain the required total power for transmission. According t o the presently disclosed subject matter, since the power stages are directly connected t o the antenna elements, and the use of cables and connectors is considerably reduces (if not eliminated), the same power can be generated using a
considerably smaller number of power stages than before. Furthermore, the power generated in a seeker and the respective power of the generated signal can exceed the power of the signal which is generated according t o the old technology mentioned above while the dimensions of the seeker can be reduced. This allows increasing the generated power and obtaining a signal transmission with greater power. It also allows reducing manufacturing costs and obtaining a seeker with a more compact design and a smaller weight. According t o the one example, the entire seeker can be mounted o n a single printed circuit board. This can be accomplished due t o the fact that the architecture includes a smaller number of discrete components and due t o the direct connection between them. As illustrated in Fig. 1 the entire seeker can be mounted o n the gimbal assembly. Fig. 1 shows an example of 4 quarter antenna. Each quarter (Q1-Q4) is connected t o single power stage (4 * Tx H P RF) for transmission. Notably, the power stage is directly connected t o a respective antenna quarter. Fig. 1 further shows each quarter is connected t o single receiving channel (5 * Rx HP RF (5 t h is for the guard channel) for reception. Notably, the RF comparator is not present. As exemplified in fig. 1 the entire seeker is mounted o n a single PCB (on the Gimbal) and accordingly the use of cables and connectors is almost completely avoided. In addition t o improved SNR and smaller dimensions (allowing mounting the entire seeker o n the Gimbal for example) the proposed architecture can also help in reducing the manufacturing complexity of the seeker as well as the price tag. Fig. 1 also shows a radio frequency intergraded circuit (2), signal generation unit SGU (3) operative connected t o the RFIC and analog t o digital converter (ADC). Also shown is pre-dsp (digital signal processing; implemented for example with firmware). Post-DSP can be implemented o n integrated ARM. Power supply unit (5) (e.g. battery)
can supply high voltage direct current (HVDC). Servo drivers and encoders (6) provide on-gimbal angle measurements. Missile avionics include control over missile flight e.g. based o n received signal reflections from target. Fig. 2 is a flowchart illustrating an example of a sequence of operation performed during interception of a single target, in accordance with the presently disclosed subject matter. Operations described with reference t o Fig. 2 can be executed for example, by electromagnetic seeker described above with reference t o Fig. 1. At block 201 signal portions are received at the antenna. At block 203, the signal portions are transmitted t o a respective receiving channel where they are amplified. The signal portions at each receiving channel is sampled and digitally processed (block 205). The digital processing includes the digital comparator functionalities including the generation of mono-pulse signals. As mentioned above, according t o the suggested approach comparator is implemented digitally and the generation of the mono-pulse signals is executed after the received signal portions have already been amplified. Fig. 3 is graph demonstrating the SNR as a function of the range between the seeker and target, according t o an example of the presently disclosed subject matter. The graphs shows the result of the operation of a seeker configured according t o the principles disclosed herein. The results of 3 different aircraft target types including: a small aircraft (RCS ~ 0.25 m 2, e.g. unmanned aerial vehicle), medium size aircraft (RCS ~ 1 m 2, e.g. F16 eagle), and a large size aircraft (RCS = 4 m 2, e.g. Boeing 747). The line at the bottom of the graph (ranging from about 32.5 d b t o about 13 db) shows the result of the small aircraft, the middle line in the graph shows the result of the medium aircraft and the top line shows the result of the large size aircraft. As can be seen in the graph, a detection range (SNR>10 db) larger than 10 km. is achieved for all three targets.
It is t o be understood that the presently disclosed subject matter is not limited in its application t o the details set forth in the description contained herein or illustrated in the drawings. The presently disclosed subject matter is capable of other embodiments and of being practiced and carried out in various ways. Hence, it is t o be understood that the phraseology and terminology employed herein are for the purpose of description and should not be regarded as limiting. As such, those skilled in the art will appreciate that the conception upon which this disclosure is based may readily be utilized as basis for designing other structures, methods, and systems for carrying out the several purposes of the presently disclosed subject matter.
CLAIMS: 1. Electromagnetic seeker comprising: an antenna having multiple radiating elements; the antenna is divided into a plurality of sections each section comprising a group of radiating elements and is directly connected t o a respective single power stage configured t o provide power t o the radiating elements; each section and a respective single power stage are configured t o provide coherent combination of signals transmitted by different antenna sections over the air t o thereby enable combination of power from all antenna sections over the air. 2. The seeker of claim 1 further comprises a respective receiving channel directly connected t o each antenna section; the receiving channel is connected further t o a processing unit comprising a digital comparator module configured t o digitally provide mono-pulse signals. 3. The seeker according t o any one of claims 1 and 2 wherein the receiving channel is configured as a single sub-assembly printed on a circuit board as single integrated unit 4. The seeker according to any one of claims 1 to 3 is mounted on a single printed circuit board. 5. The seeker according t o claim 1 wherein each one of the single power stages is printed on the opposite side of the antenna printed circuit board. 6. The seeker according t o any one of the preceding claims is mounted entirely on a gimbal assembly. 7. The seeker according t o any one of the preceding claims is a laser seeker.
A. CLASSIFICATION O F SUBJECT MATTER IPC (2017.01) G01S 13/42 According to International Patent Classification (IPC) or to both national classification and IPC B. FIELDS SEARCHED Minimum documentation searched (classification system followed by classification symbols) IPC (2017.01) G01S 13/00 Documentation searched other than minimum documentation to the extent that such documents are included in the fields searched Electronic data base consulted during the international search (name of data base and, where practicable, search terms used) Databases consulted: THOMSON INNOVATION, FamPat database C. DOCUMENTS CONSIDERED TO BE RELEVANT Category* Citation of document, with indication, where appropriate, of the relevant passages Relevant to claim No. A U S 2014253368 A l HOLDER ERNEST JEFFERSON; PROPAGATION RES ASSOCIATES 1-7 INC 11 Sep 2014 (2014/09/1 1) The whole document A U S 2015002330 A l BINZER THOMAS; BRUEGGEMANN OLIVER; WALDSCHMIDT 1-7 CHRISTIAN; STEINBUCH DIRK 0 1 Jan 2015 (2015/01/01) The whole document A U S 2013249772 A l SELEX E S SPA 1 26 Sep 2013 (2013/09/26) The whole document A U S 5995062 A HARRIS CORP 1,2 30 Nov 1999 (1999/1 1/30) The whole document Further documents are listed in the continuation of Box C. X See patent family annex. * Special categories of cited documents: later document published alter the international filing date or priority "A" document defining the general state of the art which is not considered to be of particular relevance date and not in conflict with the application but cited to understand the principle or theory underl ng the invention "E" earlier application or patent but published on or after the χ» document of particular relevance; the claimed invention cannot be international filing date considered novel or cannot be considered to involve an inventive L" document which ma throw doubts on priority claim(s) or which is step when the document is taken alone ¾¾ date f a t e a o h Ύ ' document of particular relevance; t e claimed invention cannot be c s a i t considered to involve an inventive step when the document is "0" document referring to an oral disclosure, use, exhibition or other combined with one or more other such documents, such combination means being obvious to a person skilled in the art P" document published prior to the international filing date but later,., -,,,.,., & document me er of the same patent iaimiy than tne priority date claimed Dale of the actual completion of he international search Date of mailing of the international search report 09 Feb 2017 13 Feb 2017 Name and mailing address of the ISA: Authorized officer Israel Patent Office BITTON Oren Technology Park, Bldg.5, Malcha, Jerusalem, 9695101, Israel Facsimile No. 972-2-5651616 Telephone No. 972-2-5657812 Form P CT ISA/2 0 (second sheet) (January 20 5)
Patent document cited search report Publication date Patent family member(s) Publication Date US 2014253368 A l 11 Sep 2014 US 2014253368 A l 11 Sep 2014 US 8854252 B2 07 Oct 2014 US 2015002330 A l 0 1 Jan 2015 US 2015002330 A l 0 1 Jan 2015 CN 103502837 A 08 Jan 2014 DE 10201 1075552 A l 15 Nov 2012 EP 2707742 A l 19 Mar 2014 O 2012152474 A l 15 Nov 2012 u s 2013249772 A l 26 Sep 2013 US 2013249772 A l 26 Sep 2013 u s 9035848 B2 19 May 2015 EP 2642587 A l 25 Sep 2013 u s 5995062 A 30 Nov 1999 US 5995062 A 30 Nov 1999 Form PCT/ISA/210 (patent family annex) (January 2015)