ION GNSS 2012
Session E2: Receivers & Antennas 2

Title: Phased Array GNSS Antenna for the Next Radio Occultation Mission
Author(s): D. Turbiner, L. Young, T.K. Meehan, Jet Propulsion Laboratory, California Institute of Technology
Date/Time: Wednesday, September 19, 2012, 2:12 p.m.
Room: 205 (NCC)

Future GNSS remote sensing instruments such as the TriG receiver require more capable antennas than those flown on missions such as COSMIC. To maximize the number of ionospheric and atmospheric profiles, the TriG will be capable of tracking legacy and new GPS signals such as L5, L2C and L1C; GLONASS CDMA and Galileo E1 and E5a. There´s been an in-house effort at JPL to develop a set of antennas that would provide excellent Radio Occultations performance as well as navigation and ionospheric profiling. This effort is on-going but near completion for a set of prototype antennas that meet or exceed the performance requirements for a mission like COSMIC-2.
We will present the design of an electronically steerable 15-element phased array to accompany the TriG instrument on the next RO mission. We will discuss specific features that help ensure the maximum scientific return. In particular, we designed custom helical and bifilar conical log-spiral elements that enable the use of minimum-loss broadband combiner networks. Also, each individual element is physically oriented and electrically phased in a way that synthesizes an array directivity pattern whose peak gains are distributed along the limb of the Earth.

According to HFSS simulations and measurements on built prototypes, we anticipate that our final antenna should achieve an effective aperture that exceeds its physical area by 15%. We anticipate a realized peak gain of 19dBic and 17dBic at GPS L1 and L2/L5 respectively. This gain drops by 6dB at 55 degree azimuth. This antenna does not exceed a 60x40x10cm volume.

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