US3769615A - Tapped praetersonic bulk delay line - Google Patents

Tapped praetersonic bulk delay line Download PDF

Info

Publication number
US3769615A
US3769615A US00266950A US3769615DA US3769615A US 3769615 A US3769615 A US 3769615A US 00266950 A US00266950 A US 00266950A US 3769615D A US3769615D A US 3769615DA US 3769615 A US3769615 A US 3769615A
Authority
US
United States
Prior art keywords
wave energy
bulk
delay line
piezoelectric
transducer
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US00266950A
Other languages
English (en)
Inventor
Klerk J De
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Westinghouse Electric Corp
Original Assignee
Westinghouse Electric Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Westinghouse Electric Corp filed Critical Westinghouse Electric Corp
Application granted granted Critical
Publication of US3769615A publication Critical patent/US3769615A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic elements; Electromechanical resonators
    • H03H9/02—Details
    • H03H9/125—Driving means, e.g. electrodes, coils

Definitions

  • ABSTRACT Praetersonic delay line means comprising transducer means for converting input electromagnetic wave energy to bulk sonic wave energy and for causing the bulk wave energy to traverse a body of piezoelectric material, together with electromagnetic antenna means positioned along the body at a point removed from the transducer means for converting the bulk sonic wave energy back to output electromagnetic wave energy which is delayed with respect to the input wave energy by an amount equal to the time required for the bulk sonic wave energy to travel from the transducer means to the antenna means.
  • TAPPED PRAETERSONIC BULK DELAY LINE BACKGROUND OF THE INVENTION As is known, signal processing at microwave frequencies frequently requires a tapped delay line, with delay times per tap ranging from a few nanoseconds to possibly a few tens of microseconds. Although delays up to 100 nanoseconds can be achieved using conventional electromagnetic coaxial cable or strip lines, both approaches are bulky. Longer delays can be achieved using elastic surface waves. The properties and applications of elastic surface waves are described, for example, in an article by de Klerk appearing in the Jan. 1971 issue of Ultrasonics. While such elastic surface waves can be used in certain applications, their use at gigahertz frequencies requires the use of scanning electron microscope techniques; and large insertion losses are inevitable .due to acoustic scattering losses as well as electrical series resistance losses.
  • acoustic as well as the electrical losses can be greatly reduced by employing praetersonic bulk waves rather than surface waves.
  • Acoustic losses for bulk waves are at least an order of magnitude less than surface wave losses at one gigahertz and approximately four orders less at gigahertz.
  • electrical losses for bulk waves can be made comparably lower than those encountered with surface waves.
  • a new and improved acoustic delay line employing praetersonic bulk waves rather than surface waves whereby the acoustic and electrical losses of the device can be minimized.
  • a delay line comprising a body of piezoelectric crystal material having a piezoelectrically active direction extending from one side of the body to the other.
  • a piezoelectric transducer is in contact with one side of the body at one end of the active direction for converting electromagnetic wave energy into bulk sonic wave energy and for causing the bulk sonic wave energy to traverse the body along the active direction.
  • Electromagnetic antenna means are provided adjacent at least one side of the body at.a point spaced from the transducer for converting the bulk acoustic wave energy back into electromagnetic wave energy which is delayed with respect to the original electromagnetic wave energy applied to the transducer by an amount equal to the time required for the bulk wave energy to travel from the transducer to the antenna means.
  • the bulk waves can be caused to traverse a solid body of piezoelectric material or, alternatively, a thin layer of piezoelectric material can be affixed to one surface of a substrate, preferably of crystalline material.
  • the antenna means can take the form of a simple loop or dipole and can comprise interdigital grids with finger lengths and spacing weighting. In the latter case, the time delay becomes a function of the frequency of the input signal.
  • FIG. 1 is an isometric view of one embodiment of the invention wherein bulk praetersonic wave energy is transmitted through a solid block of piezoelectric crystal material;
  • FIG. 2 is a side view of the device of FIG. 1;
  • FIG. 3 is an illustration of another embodiment of the invention wherein the piezoelectric crystal material is mounted on a substrate;
  • FIG. 4 is an illustration of still another embodiment of the invention wherein piezoelectric crystal material is mounted on opposite sides of a substrate and the antenna means is in the form of spaced dipoles, which provide for different time delays;
  • FIG. 5 is an illustration of an interdigital grid to be used as the antenna means of the invention with finger lengths and spacing weighting to achieve a time delay dependent upon frequency; and i 9 FIG. 6 is a graph of frequency versus delay time showing the manner in which the time delay decreases as frequency increases with the embodiment of FIG. 5.
  • the delayline shown includes a block 10 of piezoelectric material having an ultrasonic transducer 12 at one end and an acoustic absorber 14 at the other end.
  • the transducer 12 may be of the type shown and described in copending application Ser. No. 71,094, filed Sept. 10, 1970. Essentially, it consists of a substrate upon which is deposited a first electrode pattern of a plurality of individual electrodes over which is deposited a single layer of piezoelectric material 16, followed by a thin layer of silicon monoxide. A second electrode pattern 18 overlies the other side of the pl- I the terminal 22 being connected to an electrode on the other side of the piezoelectric layer. Further details of the transducer can be obtained by reference to the aforesaid copending application Ser. No. 71,094.
  • the piezoelectric transducer 12 at one end of the block of piezoelectric material 10 is excited by electromagnetic wave energy, the bulk praetersonic waves will be caused to traverse the block .10 in a piezoelectrically active direction from the transducer 12 to the acoustic absorber 14.
  • an acoustic or elastic wave of this type propagates along a piezoelectrically active direction in a piezoelectric crystal, the elastic wave acts as a moving source of electromagnetic energy.
  • the resulting electromagnetic alternating current fields can be readily detected by means of an electromagnetic antenna.
  • the antenna comprises a pair of loops or taps 24 and 26 which extend around the four sides of the block 10 of piezoelectric material and are provided with output terminals 28 from which electromagnetic wave energy can be derived, the electromagnetic wave energy on the respective terminals 28 being delayed with respect to that applied to the transducer 12 via terminals 20 and 22 by virtue of the delay encountered in the acoustic wave traveling through the block 10.
  • bulk compressional waves are launched in the block 10 by the transducer 12; while the loops 24 and 26 detect the traveling electromagnetic waves.
  • the spacing, d, between loops is determined by the delay time, t, per tap, and the acoustic velocity, v. That is,
  • the block 10 is formed from LiNbO and assume that delay steps of five nanoseconds are required. The distance between taps would then be:
  • the acoustic wavelength of compressional bulk waves in LiNbO at one gigahertz is given by:
  • each delay tap loop 24 or 26 is made one wavelength wide, the electromagnetic field at both edges of the loop would be in phase. This would result in the generation of an electromagnetic signal. Successive loops spaced 36.5 X 10" cm. apart would result in dealy steps of five nanoseconds. Coded tapped delay lines could also be fabricated using this design. In this aPplication, the spacing between taps could be varied to generate or detect the desired code, simply by arranging the relative phases of the tapped signals to conform to the desired codes. It is preferable that the loops 24 and 26 be electrically shielded from one another by, for example, grounded metal strips 30 as shown in FIG. 2. i
  • FIG. 3 another embodiment of the invention is shown wherein a thin film of piezoelectric material, such as LiNbO is supported on a substrate 34 which may comprise fused quartz or any other suitable material.
  • a metalized grounded surface 36 separates the substrate of quartz 34 and the layer 32 of piezoelectric material.
  • a thin film mosaic bulk wave transducer 38 such as transducer 12 shown in FIG. 1, is provided at one end of the thin film of piezoelectric crystal material 32.
  • the antenna means in this case comprises interleaved grids 40 and 42 spaced along the length of the piezoelectric crystal 32 and ach provided with output terminals 44 and 46, respectively. In this manner, the electromagnetic wave energy appearing at terminals 46 will be delayed by a greater amount than that appearing at terminal 44.
  • Electromagnetic wave energy applied to terminals 48 of the transducer 38 is converted into bulk praetersonic wave energy which travels through the piezoelectric layer 32, the resultant moving source of electromagnetic wave energy being detected by the antenna means 40 and 42 at different points in time.
  • FIG. 4 still another embodiment of the invention is shown wherein layers 50 and 52 of low loss, high velocity non-piezoelectric crystal material are deposited on opposite sides of a substrate 54 of fused quartz or the like, the layers and 52 being separated from the substrate 54 by means of ground planes or metalizations 56.
  • the non-piezoelectric material may, for example, comprise ruby, sapphire or silicon.
  • Piezoelectric transducers 58 and 60 for converting electromagnetic wave energy into bulk praetersonic wave energy are provided at one end of each of the layers 50 and 52. These, again, serve to induce bulk praetersonic wave energy which travels along the crystals 50 and 52.
  • Deposited on top of the layers 50 and 52 are layers 51 and 53 of piezoelectric material such as that described above.
  • the antenna means in this case comprises interleaved dipoles 62 which can be provided on both piezoelectric films 51 and 53 at spaced points to achieve different time delays.
  • FIG. 5 an interdigital grid with finger length and spacing weighting is shown which can be applied to a surface of the piezoelectric body to achieve a time delay dependent upon the frequency of the input signal.
  • the output terminals 64 and 66 of the grid of FIG. 5 are on opposite sides of the interleaved fingers of the grid. Note that the interleaved fingers at the left end of the grid of FIG. 5 are more widely spaced apart than those at the right side, the spacing gradually decreasing from left to right.
  • the grids shown in FIG. 5 respond to the lowest input frequencies at the left-hand side and to the highest frequencies at the right-hand side. Assuming, therefore, that the grid of FIG.
  • FIG. 5 is deposited on the surface of a piezoelectric crystal and that bulk wave energy is caused to traverse the piezoelectric crystal from left to right, a frequency response will be achieved as shown in FIG. 6 wherein the lowest frequencies have the shortest time delay and the highest frequenices have the greatest time delay. Further details of the manner in which the grid of FIG. 5 can be fabricated are found in the aforesaid article by John de Klerk appearing in the Jan. I971 issue of Ultrasonics.
  • Delay line means comprising transducer means for converting input electromagnetic wave energy to bulk compressional wave energy and for causing said bulk wave energy to traverse a body of piezoelectric material, and electromagnetic antenna means positioned along said body at a point removed from the transducer means for converting said bulk compressional wave energy back to output electromagnetic wave energy which is delayed with respect to the input wave energy, said antenna means comprising at least two parallel line electrodes on at least one face of said body.
  • the delay line means of claim 1 wherein said antenna means comprises a loop extending around said body of piezoelectric material in a plane extending transverse to the direction of movement of said bulk compressional wave energy through the piezoelectric body.
  • Delay line means comprising a body of piezoelectric crystal material having a piezo-electrically active direction extending from one side of the body to the other, a piezoelectric transducer in contact with said one side of the body for converting electromagnetic wave energy to bulk compressional wave energy and for causing said bulk compressional wave energy to traverse the body along said active direction, and electromagnetic antenna means on at least one side of the body for converting said bulk compressional wave energy back to electromagnetic wave energy which is delayed with respect to the electromagnetic wave energy applied to said transducer, said antenna means comprising at least two parallel line electrodes on said one side of the body.
  • the delay line means of claim 6 including an acoustic absorber at the end of said piezoelectric body opposite said piezoelectric transducer.

Landscapes

  • Physics & Mathematics (AREA)
  • Acoustics & Sound (AREA)
  • Surface Acoustic Wave Elements And Circuit Networks Thereof (AREA)
  • Piezo-Electric Or Mechanical Vibrators, Or Delay Or Filter Circuits (AREA)
US00266950A 1972-06-28 1972-06-28 Tapped praetersonic bulk delay line Expired - Lifetime US3769615A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US26695072A 1972-06-28 1972-06-28

Publications (1)

Publication Number Publication Date
US3769615A true US3769615A (en) 1973-10-30

Family

ID=23016647

Family Applications (1)

Application Number Title Priority Date Filing Date
US00266950A Expired - Lifetime US3769615A (en) 1972-06-28 1972-06-28 Tapped praetersonic bulk delay line

Country Status (4)

Country Link
US (1) US3769615A (enExample)
JP (1) JPS4945667A (enExample)
GB (1) GB1425849A (enExample)
TR (1) TR17605A (enExample)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4259649A (en) * 1979-07-26 1981-03-31 Westinghouse Electric Corp. Electroacoustic delay line apparatus
US4292608A (en) * 1979-07-26 1981-09-29 Westinghouse Electric Corp. Electroacoustic delay line apparatus
US4523293A (en) * 1983-04-05 1985-06-11 The United States Of America As Represented By The Secretary Of The Air Force Two-dimensional bulk acoustic wave correlator-convolver
US5359250A (en) * 1992-03-04 1994-10-25 The Whitaker Corporation Bulk wave transponder
US20020149300A1 (en) * 2001-04-12 2002-10-17 Jyrki Kaitila Method of producting thin-film acoustic wave devices
US9473106B2 (en) 2011-06-21 2016-10-18 Georgia Tech Research Corporation Thin-film bulk acoustic wave delay line

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3037174A (en) * 1958-12-31 1962-05-29 Bell Telephone Labor Inc Microwave ultrasonic delay line

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4259649A (en) * 1979-07-26 1981-03-31 Westinghouse Electric Corp. Electroacoustic delay line apparatus
US4292608A (en) * 1979-07-26 1981-09-29 Westinghouse Electric Corp. Electroacoustic delay line apparatus
US4523293A (en) * 1983-04-05 1985-06-11 The United States Of America As Represented By The Secretary Of The Air Force Two-dimensional bulk acoustic wave correlator-convolver
US5359250A (en) * 1992-03-04 1994-10-25 The Whitaker Corporation Bulk wave transponder
US20020149300A1 (en) * 2001-04-12 2002-10-17 Jyrki Kaitila Method of producting thin-film acoustic wave devices
US6548943B2 (en) * 2001-04-12 2003-04-15 Nokia Mobile Phones Ltd. Method of producing thin-film bulk acoustic wave devices
US9473106B2 (en) 2011-06-21 2016-10-18 Georgia Tech Research Corporation Thin-film bulk acoustic wave delay line

Also Published As

Publication number Publication date
TR17605A (tr) 1975-07-23
GB1425849A (en) 1976-02-18
JPS4945667A (enExample) 1974-05-01

Similar Documents

Publication Publication Date Title
US3568102A (en) Split surface wave acoustic delay line
US3568108A (en) Thin film piezoelectric filter
White Surface elastic-wave propagation and amplification
US3836876A (en) Acoustic surface wave devices
Joshi et al. Excitation and detection of surface elastic waves in piezoelectric crystals
US3833867A (en) Acoustic surface wave convolver with bidirectional amplification
US3786373A (en) Temperature compensated acoustic surface wave device
US3678305A (en) Acoustic surface wave devices
US3675163A (en) Cascaded f. m. correlators for long pulses
EP0435189A2 (en) Surface acoustic wave device
US3955160A (en) Surface acoustic wave device
US3686518A (en) Unidirectional surface wave transducers
Schmidt et al. Piezoelectric elastic surface waves in anisotropic layered media
US3678304A (en) Acoustic wave device for converting bulk mode waves to surface waves and vice versa
US3662293A (en) Acoustic-wave transmitting device
US3760299A (en) Acoustic surface wave-apparatus having dielectric material separating transducer from acoustic medium
Kino et al. Signal processing in acoustic surface-wave devices
US3387233A (en) Signal dispersion system
US3769615A (en) Tapped praetersonic bulk delay line
US3972011A (en) Surface elastic wave electromechanical device
US3654574A (en) Acoustic-wave transmitting system having curvilinear transducers
US3795879A (en) Composite dispersive filter
US3878407A (en) Surface wave electromechanical filter
US3825779A (en) Interdigital mosaic thin film shear transducer
US3611203A (en) Integrated digital transducer for variable microwave delay line