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Lens Based High Directivity Simultaneous Transmit and Receive Systems.

紀錄類型:	書目-電子資源 : Monograph/item
正題名/作者:	Lens Based High Directivity Simultaneous Transmit and Receive Systems./
作者:	Mulero Hernandez, Carlos A.
出版者:	Ann Arbor : ProQuest Dissertations & Theses, : 2021,
面頁冊數:	109 p.
附註:	Source: Dissertations Abstracts International, Volume: 83-03, Section: B.
Contained By:	Dissertations Abstracts International83-03B.
標題:	Electrical engineering. -
電子資源:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=28541143
ISBN:	9798538119400

Lens Based High Directivity Simultaneous Transmit and Receive Systems.
Mulero Hernandez, Carlos A.

Lens Based High Directivity Simultaneous Transmit and Receive Systems. - Ann Arbor : ProQuest Dissertations & Theses, 2021 - 109 p.

Source: Dissertations Abstracts International, Volume: 83-03, Section: B.

Thesis (Ph.D.)--University of Colorado at Boulder, 2021.

This item must not be sold to any third party vendors.

Simultaneous transmit and receive (STAR) has the potential to theoretically double the capacity of wireless networks making it a highly desirable technology for modern wireless systems. Self interference (SI) is the chief challenge and high Tx/Rx isolation (greater than 100 dB) is required to mitigate this issue and realize STAR operation. The required isolation level is typically achieved by using a multi-layer cancellation approach across the antenna, analog, and digital domains. A well-designed antenna or propagation layer can provide a significant portion of the SI cancellation (SIC) enabling simplified and more practical transceiver realization. For typical wireless networks and electronic warfare systems, monostatic or shared-aperture STAR antennas are often required to maintain the aperture compactness. At millimeter waves, high directivity and beam steering characteristics are highly desired; particularly for access point and backhaul antennas, to overcome the path loss, achieve the required communication range, and improve the signal-to-noise ratio in dynamic multi-user environments.A co-polarized, co-channel STAR antenna system utilizing a two-layer, spherically stratified lens with nominal directivity of 24.3 dBic is demonstrated in the 27 to 29 GHz frequency band. The STAR operation is achieved with a WR28 waveguide-implemented balanced circulator beam forming network (BC-BFN), which relies on two 90deg hybrids and two circulators along with antenna symmetry to cancel the circulator leakages and achieve theoretically infinite isolation between the transmit and receive ports. The sensitivity of the BC-BFN to alignment and other imperfections is studied. To comply with the BC-BFN's symmetry requirements, a highly symmetric WR28 waveguide ortho-mode transducer (OMT) is developed. Tx/Rx isolation of 30 and 34 dB is measured with and without the lens, respectively, indicating acceptable impact of the lens on system isolation. To demonstrate STAR with the beam steering in an equatorial field of view, the proposed configuration is modified into a mechanically rotated half spherical lens over a ground plane. The experiments show that the isolation of the rotating half-lens system degrades compared to the full-lens counterpart due to the break of the geometrical symmetry. However, respectable isolation greater than 27 dB and high quality circularly polarized radiation patterns are still maintained over the operational bandwidth. Another co-polarized, co-channel, lens-based STAR system based of the same BC-BFN and OMT subsystem but using a compact planar graded index (GRIN) lens is also introduced. The compact lens achieves broadside directivity greater than 24 dBic in the band centered about 28 GHz. The beams are steered by mechanically rotating the proposed compact lens, maintaining the focal point on the antenna's phase center. A maximum scan loss of 4.5 dB is seen in an 80deg conic field of view while preserving system isolation. The measured system maintains 30 dB of isolation with at most 2 dB degradation in isolation at the more severe inclination angles.Finally, closed-form expressions are derived for the component of the radar cross section (RCS) due to the BFN in the context of retrodirective systems. The ability to accurately predict the effect of feedback and infinite reflections is shown with numerical simulations. The derived equations allow calculating the bounds for the maximum loop gain for the system before feedback leads its response into the non-linear domain. The potential of using STAR to improve the performance of retrodirective systems is evaluated with the spherical lens antenna and BC-BFN subsystem. Improvements of 20 dB are obtained when data from the fabricated STAR system is used in the equation and compared to passive lens reflectors.

ISBN: 9798538119400Subjects--Topical Terms:

649834
Electrical engineering.
Subjects--Index Terms:

Circulator

Lens Based High Directivity Simultaneous Transmit and Receive Systems.
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300 $a 109 p.
500 $a Source: Dissertations Abstracts International, Volume: 83-03, Section: B.
500 $a Advisor: Filipovic, Dejan S.
502 $a Thesis (Ph.D.)--University of Colorado at Boulder, 2021.
506 $a This item must not be sold to any third party vendors.
520 $a Simultaneous transmit and receive (STAR) has the potential to theoretically double the capacity of wireless networks making it a highly desirable technology for modern wireless systems. Self interference (SI) is the chief challenge and high Tx/Rx isolation (greater than 100 dB) is required to mitigate this issue and realize STAR operation. The required isolation level is typically achieved by using a multi-layer cancellation approach across the antenna, analog, and digital domains. A well-designed antenna or propagation layer can provide a significant portion of the SI cancellation (SIC) enabling simplified and more practical transceiver realization. For typical wireless networks and electronic warfare systems, monostatic or shared-aperture STAR antennas are often required to maintain the aperture compactness. At millimeter waves, high directivity and beam steering characteristics are highly desired; particularly for access point and backhaul antennas, to overcome the path loss, achieve the required communication range, and improve the signal-to-noise ratio in dynamic multi-user environments.A co-polarized, co-channel STAR antenna system utilizing a two-layer, spherically stratified lens with nominal directivity of 24.3 dBic is demonstrated in the 27 to 29 GHz frequency band. The STAR operation is achieved with a WR28 waveguide-implemented balanced circulator beam forming network (BC-BFN), which relies on two 90deg hybrids and two circulators along with antenna symmetry to cancel the circulator leakages and achieve theoretically infinite isolation between the transmit and receive ports. The sensitivity of the BC-BFN to alignment and other imperfections is studied. To comply with the BC-BFN's symmetry requirements, a highly symmetric WR28 waveguide ortho-mode transducer (OMT) is developed. Tx/Rx isolation of 30 and 34 dB is measured with and without the lens, respectively, indicating acceptable impact of the lens on system isolation. To demonstrate STAR with the beam steering in an equatorial field of view, the proposed configuration is modified into a mechanically rotated half spherical lens over a ground plane. The experiments show that the isolation of the rotating half-lens system degrades compared to the full-lens counterpart due to the break of the geometrical symmetry. However, respectable isolation greater than 27 dB and high quality circularly polarized radiation patterns are still maintained over the operational bandwidth. Another co-polarized, co-channel, lens-based STAR system based of the same BC-BFN and OMT subsystem but using a compact planar graded index (GRIN) lens is also introduced. The compact lens achieves broadside directivity greater than 24 dBic in the band centered about 28 GHz. The beams are steered by mechanically rotating the proposed compact lens, maintaining the focal point on the antenna's phase center. A maximum scan loss of 4.5 dB is seen in an 80deg conic field of view while preserving system isolation. The measured system maintains 30 dB of isolation with at most 2 dB degradation in isolation at the more severe inclination angles.Finally, closed-form expressions are derived for the component of the radar cross section (RCS) due to the BFN in the context of retrodirective systems. The ability to accurately predict the effect of feedback and infinite reflections is shown with numerical simulations. The derived equations allow calculating the bounds for the maximum loop gain for the system before feedback leads its response into the non-linear domain. The potential of using STAR to improve the performance of retrodirective systems is evaluated with the spherical lens antenna and BC-BFN subsystem. Improvements of 20 dB are obtained when data from the fabricated STAR system is used in the equation and compared to passive lens reflectors.
590 $a School code: 0051.
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650 4 $a Electromagnetics. $3 3173223
653 $a Circulator
653 $a Lens
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653 $a Simultaneous transmit and receive systems
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710 2 $a University of Colorado at Boulder. $b Electrical Engineering. $3 1025672
773 0 $t Dissertations Abstracts International $g 83-03B.
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791 $a Ph.D.
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793 $a English
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