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An acoustically coupled antenna which can be configured as a transmitting or receiving antenna for coupling between an electrical circuit (transmitter or receiver) and an electromagnetic propagating medium such as the atmosphere. The antenna is a two port device in which one port is connected to the

An acoustically coupled antenna which can be configured as a transmitting or receiving antenna for coupling between an electrical circuit (transmitter or receiver) and an electromagnetic propagating medium such as the atmosphere. The antenna is a two port device in which one port is connected to the electrical circuit and the second port includes a transducer which interfaces (radiates or receives) electromagnetic energy with the propagating medium. The ports are acoustically coupled to each other by forming the device as a stacked crystal filter with three conductive electrodes separated by two piezoelectric resonating elements. The first port comprises two of the electrodes separated by one of the piezoelectric elements, and the second port shares the electrode separating the two piezoelectric elements, and further includes the second piezoelectric element and the final electrode. The electrical signals in the bandwidth of the antenna at the two ports are acoustically coupled by the coupled resonators of the stacked crystal filter for translating energy from one port to the other while providing electromagnetic isolation by virtue of the acoustic coupling.

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1. An antenna for coupling energy in a predetermined frequency band between an electrical circuit and an electromagnetic propagating medium, the antenna comprising, in combination: a first port coupled to and electrically matched to the electrical circuitry for exchanging energy therewith, a sec

1. An antenna for coupling energy in a predetermined frequency band between an electrical circuit and an electromagnetic propagating medium, the antenna comprising, in combination: a first port coupled to and electrically matched to the electrical circuitry for exchanging energy therewith, a second port having a transducer for interfacing between the antenna and the propagating medium, the transducer having no leads connected thereto and serving to convert between electrical signals in the transducer and electromagnetic radiation in the propagating medium, and means for acoustically coupling the first and second ports, the acoustical coupling means serving to translate between electrical energy in the predetermined frequency band at the ports and acoustical energy for coupling between the ports, the acoustical coupling means including coupled piezoelectric resonators for providing the acoustical coupling, the first port including first electrode means formed on the piezoelectric resonators and connected to the electrical circuitry for transforming between electrical energy in the electrical circuitry and acoustical energy in the piezoelectric resonators, the second port including second electrode means formed on the piezoelectric resonators, said second electrode means serving as the transducer for coupling energy between the propagating medium and the piezoelectric resonators. 2. The combination as set forth in claim 1, wherein the first port comprises a pair of electrodes separated by a first piezoelectric resonator, the second port comprises a pair of electrodes separated by a second piezoelectric resonator, one of the electrodes of the first and second ports being a common electrode disposed in both said ports, whereby the piezoelectric resonators separated by the common electrode serve as the coupling means between the ports, the non-common electrode of the second port serving as said transducer for coupling energy between the piezoelectric resonators and the propagating medium. 3. The combination as set forth in claim 1 wherein the ports and coupling means are configured as a stacked crystal filter comprising three thin film electrodes disposed on and separated by first and second thin film piezoelectric resonating elements, a central one of the three electrodes being shared by the two ports, the piezoelectric resonators being acoustically coupled for acoustically coupling energy between the ports and translating the coupled energy to or from electrical energy at the ports. 4. The combination as set forth in claim 3 wherein the electrical circuit and stacked crystal filter are supported on a common semiconductor or semi-insulator substrate. 5. A phased antenna array comprising a plurality of antenna elements as set forth in claim 3 and wherein the electrical circuit includes phase control means for phasing the elements in the antenna array. 6. An antenna for coupling energy in a predetermined frequency band between an electrical circuit and an electromagnetic propagating medium capable of propagating electromagnetic energy in said predetermined frequency band, the antenna comprising the combination of: a first port for interfacing electrical energy between the electrical circuit and the antenna in the predetermined frequency band, a second port having a transducer for interfacing between the propagating medium and the antenna in the predetermined frequency band, the transducer having no leads connected thereto and serving to convert between electrical signals in the transducer and electromagnetic radiation in the propagating medium, and acoustical coupling means for acoustically coupling energy in the predetermined frequency band between the first and second ports, the acoustical coupling means including coupled piezoelectric resonators for converting between electrical and acoustical energy in the predetermined frequency band, the first port including first electrode means formed on the coupled piezoelectric resonators and connected to the electrical circuit for transforming between electrical energy in the electrical circuit and acoustical energy in the piezoelectric resonators, the second port including second electrode means formed on the coupled piezoelectric resonators for transforming between electrical energy in the second electrode means and acoustical energy in the coupled piezoelectric resonators, the second electrode means being disposed for coupling electromagnetic energy with the propagating medium, thereby to serve as the transducer of the second port for coupling with the propagating medium. 7. The combination as set forth in claim 6 in which the first and second ports and the coupling means comprise a thin film stacked crystal filter, the stacked crystal filter having first and second thin film piezoelectric resonators separated by a thin film common electrode and sandwiched by first and second thin film electrodes associated respectively with the first and second piezoelectric resonators, the stacked crystal filter comprising said coupled piezoelectric resonators of the coupling means, the first and common electrodes associated with the first piezoelectric resonator including connecting means for coupling to the electrical circuit for interfacing electrical energy in the predetermined frequency band therewith, the second electrode associated with the second piezoelectric resonator comprising said transducer for coupling energy between the second port and the propagating medium in the predetermined frequency band. 8. The combination as set forth in claim 7 in which the common electrode is grounded and serves as a shield against electromagnetic interference protecting said first port from electromagnetic radiation outside of the predetermined frequency band. 9. The combination as set forth in claim 8 wherein the grounded common electrode serves as a ground plane for said transducer. 10. The combination as set forth in claim 7 in which the antenna is a transmitting antenna, the electrical circuit being a transmitter driver for connection to the first port for exciting the first piezoelectric resonator therein, the transducer being a radiator of electromagnetic energy in the predetermined frequency band, the coupling means serving to couple acoustic energy from the first piezoelectric resonator to the second piezoelectric resonator and translate said coupled acoustical energy into electrical energy in the second port for radiation by the transducer. 11. The combination as set forth in claim 7 in which the antenna is a receiving antenna, the electrical circuit being an electrical receiver for receiving electrical signals from the first port, the transducer in the second port being adapted to receive electromagnetic energy from the propagating medium and excite the second piezoelectric resonator, the coupling means serving to couple acoustical energy from the second to the first piezoelectric resonator for translation into electrical signals by the first piezoelectric resonator and coupling to said electrical receiver. 12. The combination as set forth in claim 7 wherein the electrical circuit and stacked crystal filter are supported on a common semiconductor or semi-insulator substrate. 13. A phased antenna array comprising a plurality of antenna elements as set forth in claim 7 and wherein the electrical circuit includes phase control means for phasing the elements in the antenna array. 14. An antenna for coupling energy in a predetermined frequency band between an electrical circuit and a propagating medium, the antenna comprising in combination: a stacked crystal filter having first, second and third thin film electrodes, the stacked crystal filter also having first and second thin film piezoelectric elements interposed respectively between the first and second and the second and third electrodes, the first and second electrodes and first piezoelectric element therebetween serving as a first port for coupling to the electrical circuit and transforming between electrical energy in the electrical circuit and acoustical energy in the piezoelectric elements, the second and third electrodes and second piezoelectric element therebetween serving as a second port for coupling to the propagating medium and transforming between acoustical energy in the piezoelectric elements and electromagnetic energy in the propagating medium, the third electrode having no lead wires connected thereto and being disposed in the propagating medium for translating between electromagnetic radiation in the medium and conductive currents in the electrode, the piezoelectric elements being resonant in the predetermined frequency band of the antenna for acoustically coupling the first and second ports in the predetermined frequency band for selectively passing energy therebetween in said frequency band. 15. The combination as set forth in claim 14 wherein the electrical circuit and stacked crystal filter are supported on a common semiconductor or semi-insulator substrate. 16. A phased antenna array comprising a plurality of antenna elements as set forth in claim 14 and wherein the electrical circuit includes phase control means for phasing the elements in the antenna array.