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You searched for subject:(Sinuous antennas). Showing records 1 – 3 of 3 total matches.

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Georgia Tech

1. Crocker, Dylan Andrew. Numerical and experimental evaluation of sinuous antennas for remote sensing applications.

Degree: PhD, Electrical and Computer Engineering, 2019, Georgia Tech

The objective of the research presented in this dissertation is to analyze the operation of the sinuous antenna and seek to overcome practical design challenges when utilizing the antenna in radar applications. The sinuous antenna can operate over ultra-wide bandwidths while producing polarization diversity, which makes the antenna an attractive candidate for polarimetric radar. However, the sinuous antenna may suffer from unintended resonant modes which distort the radiation and will produce ringing when the antenna is used to transmit pulses. An investigation was performed to determine the correlation between design parameters and these resonant modes. Design guidance is presented, which mitigates the excitation of these modes. A new sinuous antenna outer truncation technique is also presented, which prevents low-frequency resonances. Dispersion in sinuous antennas is another undesirable characteristic when radiating pulses.Since the active region on the antenna moves with frequency, the spectral content of the radiation is spread out over time. The original pulse may be reconstructed by applying a phase correction that compensates the dispersive effects. A simple dispersion model that is suitable for a fieldable system is proposed and implemented, which allows the antenna to transmit and receive temporally short pulses successfully. With these design challenges overcome, a new sinuous antenna was developed for the detection of targets close to the ground surface with ground-penetrating radar (GPR). GPR systems often employ a bistatic antenna configuration; however, this leads to extreme bistatic angles when attempting to detect targets close to the ground surface, which often reduces system performance. The operation of the sinuous antenna as an array of closely spaced yet independent arms is investigated as a potential quasi-monostatic antenna with a low height profile. The quasi-monostatic configuration dramatically reduces the bistatic angles, which significantly improves performance for close-in targets while keeping the isolation to a manageable level. A prototype antenna is fabricated and integrated into a GPR testbed. The polarimetric nature of the antenna allows for the discrimination between linear and circular targets, which is demonstrated with measured data. Advisors/Committee Members: Scott, Waymond R. (advisor).

Subjects/Keywords: Antennas; Sinuous antennas; Radar; Ground-penetrating radar

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APA (6th Edition):

Crocker, D. A. (2019). Numerical and experimental evaluation of sinuous antennas for remote sensing applications. (Doctoral Dissertation). Georgia Tech. Retrieved from http://hdl.handle.net/1853/62321

Chicago Manual of Style (16th Edition):

Crocker, Dylan Andrew. “Numerical and experimental evaluation of sinuous antennas for remote sensing applications.” 2019. Doctoral Dissertation, Georgia Tech. Accessed December 02, 2020. http://hdl.handle.net/1853/62321.

MLA Handbook (7th Edition):

Crocker, Dylan Andrew. “Numerical and experimental evaluation of sinuous antennas for remote sensing applications.” 2019. Web. 02 Dec 2020.

Vancouver:

Crocker DA. Numerical and experimental evaluation of sinuous antennas for remote sensing applications. [Internet] [Doctoral dissertation]. Georgia Tech; 2019. [cited 2020 Dec 02]. Available from: http://hdl.handle.net/1853/62321.

Council of Science Editors:

Crocker DA. Numerical and experimental evaluation of sinuous antennas for remote sensing applications. [Doctoral Dissertation]. Georgia Tech; 2019. Available from: http://hdl.handle.net/1853/62321


Stellenbosch University

2. Du Toit, Zainodean. Wideband low loss feed integration with a pyramidal sinuous antenna.

Degree: MEng, Electrical and Electronic Engineering, 2020, Stellenbosch University

ENGLISH ABSTRACT: In this thesis, a pyramidal sinuous antenna is designed to be integrated with a balun. This system is to be used as the feed of a shaped, offset Gregorian reflector. Initially, a previously designed Marchand balun is chosen due to its maximum amplitude and phase unbalance of ±0.2 dB and 1.5◦ , respectively. The balun matched the antennas 300 Ω real input impedance component across a 4.5:1 band. A new descrambling network is also designed to allow for the integration of two baluns, yielding a dual polarised sinuous antenna. Using this descrambling network, simulations showed that the antenna and balun integration matched a previous, single polarised integration. The simulated reflection coefficient remained below -10 dB across the majority of the band, reaching a maximum of -7.5 dB. The simulated radiation pattern also showed symmetry across the band, with a BOR1 (body of revolution type 1) efficiency above 90% and a reflector aperture efficiency above 70%. While the measured radiation pattern also showed symmetry, the reflection coefficient reached a maximum of -6 dB. Due to the measured reflection coefficient of the integrated balun and antenna, a Phelan balun is designed and suggested as an improvement. This balun was chosen for its inherent 4:1 impedance transformation. Balun simulations showed a maximum amplitude unbalance of 0.02 dB, and a maximum phase unbalance of 3.5% across a 0.26-1.8 GHz range. The simulated and measured reflection coefficient for this balun remained well below -10 dB across the same range.

AFRIKAANSE OPSOMMING:In hierdie tesis is ’n piramidiese sinusvormige antenna ontwerp om met ’n balun geïntegreer te word. Hierdie stelsel moet dan gebruik word as voer vir ’n gevormde, gekompenseerde Gregoriaanse weerkaatser. Aanvanklik word ’n voorheen ontwerpte Marchand-balun gekies as gevolg van sy maksimum amplitude en fase-onbalans van onderskeidelik ±0.2 dB en 1.5◦. Die balun pas by die antenna se 300 Ω reële invoerimpedansie-komponent oor ’n band van 1.05-4.7 GHz.’n Nuwe ontknopingsnetwerk is ook ontwerp om die inskakeling van twee baluns moontlik te maak, wat ’n dubbele gepolariseerde sinusvormige antenna lewer. Met behulp van hierdie ontknopingsnetwerk het simulasies getoon dat die antenna- en balun-integrasie ooreenstem met ’n vorige, enkel gepolariseerde integrasie. Die gesimuleerde weerkaatskoëffisiënt bly onder -10 dB oor die grootste deel van die band, en bereik ’n maksimum van -7.5 dB. Die gesimuleerde stralingspatroon het ook simmetrie oor die hele band getoon, met ’n BOR1 doeltreffendheid bo 90% en ’n reflektoropening doeltreffendheid bo 70%. Terwyl die gemete stralingspatroon ook simmetrie getoon het, bereik die weerkaatskoëffisiënt ’n maksimum van -6 dB. As gevolg van die gemete weerkaatskoëffisiënt van die geïntegreerde balun en antenna, word ’n Phelan-balun ontwerp en voorgestel as verbetering. Hierdie balun is gekies vir die inherente 4:1 impedansie transformasie. Simulasies het ’n maksimale amplitude-onbalans van 0.02 dB getoon, en ’n maksimum…

Advisors/Committee Members: Van Niekerk, C., De Villiers, D. I. L., Stellenbosch University. Faculty of Engineering. Dept. of Electrical and Electronic Engineering..

Subjects/Keywords: Marchand-balun; Pyramidal sinuous antenna; Ultra-wideband antennas; Antennas (Electronics); UCTD

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Du Toit, Z. (2020). Wideband low loss feed integration with a pyramidal sinuous antenna. (Thesis). Stellenbosch University. Retrieved from http://hdl.handle.net/10019.1/107860

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16th Edition):

Du Toit, Zainodean. “Wideband low loss feed integration with a pyramidal sinuous antenna.” 2020. Thesis, Stellenbosch University. Accessed December 02, 2020. http://hdl.handle.net/10019.1/107860.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7th Edition):

Du Toit, Zainodean. “Wideband low loss feed integration with a pyramidal sinuous antenna.” 2020. Web. 02 Dec 2020.

Vancouver:

Du Toit Z. Wideband low loss feed integration with a pyramidal sinuous antenna. [Internet] [Thesis]. Stellenbosch University; 2020. [cited 2020 Dec 02]. Available from: http://hdl.handle.net/10019.1/107860.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Du Toit Z. Wideband low loss feed integration with a pyramidal sinuous antenna. [Thesis]. Stellenbosch University; 2020. Available from: http://hdl.handle.net/10019.1/107860

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation


University of California – Berkeley

3. OBrient, Roger. A Log-Periodic Focal-Plane Architecture for Cosmic Microwave Background Polarimetry.

Degree: Physics, 2010, University of California – Berkeley

We describe the design, fabrication, and laboratory-demonstration of a novel dual-polarized multichroic antenna-coupled Transition Edge Sensor (TES) bolometer. Each pixel separates the incident millimeter radiation into two linear polarization channels as well as several frequency channels (bands). This technology enables us to realize bolometer arrays for Cosmic Microwave Background (CMB) polarimetry measurements that map the sky at multiple colors while simultaneously boosting the optical throughput over what would have been attained from arrays of single-frequency channel detectors. Observations at multiple frequency channels are important for differentiating polarized galactic foregrounds and atmospheric fluctuations from the CMB.Each pixel couples free-traveling radiation onto lithographed microstrip transmission lines prior to the bolometers using a dual-polarized broadband antenna known as a sinuous antenna. The transmission lines are integrated onto the back of the antenna arms and the antennas are in direct contact with an extended-hemispherical lens. We show measurements of scale model (4-12GHz) and to-scale (80-240Hz) antennas to demonstrate high antenna-gain, low cross-polarization contamination, and efficient coupling over a 1-2 octave bandwidth.We have developed microstrip circuits that divide the antenna's wide bandwidth into smaller channels. In one scheme, two or three frequency channels can be extracted from the antenna's received power using microstrip circuits known as diplexers and triplexers. These avoid atmospheric spectral lines and are well suited to terrestrial observations. We can also partition this bandwidth into contiguous bands using cochlear channelizers inspired by the physiology of the human ear; this design is most advantageous for satellite missions where there are no concerns about atmospheric contamination. We present design methodologies for these circuits and show measurements of prototypes coupled to TES bolometers to verify acceptable performance. We also describe the fabrication of a broadband anti-reflection coating for the contacting lenses and demonstrate that lens-coupled sinuous pixels receive more power with the coatings than without. Finally, we remark on the last un-resolved challenge of forming symmetric beams and balun designs that may help form patterns more useful for polarimetry.This technology is a candidate for use in the Polarbear ground-based experiment. By packing more detectors into the focal-plane than can be done with monochromatic pixels, multichroic pixels will allow Polarbear to map the sky much faster. This technology is also candidate for future space-based missions as well, where multhchroic pixels will allow a less massive payload and hence a lower cost mission. Finally, we envision using arrays of similar pixels in sub-millimeter observations of high-redshift galaxy clusters as well (e.g.example Sunyaev-Zeldovich Effect measurements). However, we require more sophisticated lithography and etching techniques to shrink these pixels…

Subjects/Keywords: Astronomy; Electromagnetics; Optics; Channelizer; Cosmic Microwave Backgeound Polarization; Log-periodic antennas and circuits; Sinuous Antenna; TES Bolometer

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

OBrient, R. (2010). A Log-Periodic Focal-Plane Architecture for Cosmic Microwave Background Polarimetry. (Thesis). University of California – Berkeley. Retrieved from http://www.escholarship.org/uc/item/8bh7z0pb

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16th Edition):

OBrient, Roger. “A Log-Periodic Focal-Plane Architecture for Cosmic Microwave Background Polarimetry.” 2010. Thesis, University of California – Berkeley. Accessed December 02, 2020. http://www.escholarship.org/uc/item/8bh7z0pb.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7th Edition):

OBrient, Roger. “A Log-Periodic Focal-Plane Architecture for Cosmic Microwave Background Polarimetry.” 2010. Web. 02 Dec 2020.

Vancouver:

OBrient R. A Log-Periodic Focal-Plane Architecture for Cosmic Microwave Background Polarimetry. [Internet] [Thesis]. University of California – Berkeley; 2010. [cited 2020 Dec 02]. Available from: http://www.escholarship.org/uc/item/8bh7z0pb.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

OBrient R. A Log-Periodic Focal-Plane Architecture for Cosmic Microwave Background Polarimetry. [Thesis]. University of California – Berkeley; 2010. Available from: http://www.escholarship.org/uc/item/8bh7z0pb

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

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