Presently researchers at goddard are planning to develop a passive system having a frequency range of 500 to 1500 MHZ. The system requires a broadband antenna to cover the complete desired frequency…

This federal contract award, with an ID of 80NSSC18K0996, is a grant for research being provided by the National Aeronautics and Space Administration (NASA) Goddard Space Flight Center to George Washington University. The purpose of the grant is to develop a passive system with a frequency range of 500 to 1500 MHz, including a broadband antenna, that will be tested in a field experiment in the summer of 2019. The experiment will use the NASA/GW L-band radar/radiometer system known as COMRAD to verify the performance of the broadband sensor. Due to budgetary constraints, a cheaper log periodic P-band antenna will be used, with COMRAD providing the L-band measurements. The grant, valued at $148,001, has an ultimate completion date of June 30, 2024. This award is not designated as a set-aside contract.

Presently researchers at goddard are planning to develop a passive system having a frequency range of 500 to 1500 MHZ. The system requires a broadband antenna to cover the complete desired frequency range. They will test the system in a field experiment in the summer of 2019. Comrad, the NASA/GW l band radar/radiometer system, can be tasked to verify that the broadband sensor is giving correct brightness temperatures at l band. Because of budgetary limitations and the high cost of a broadband antenna, a modified plan has evolved. A cheaper log periodic p band antenna will be employed in the field experiment with comrad providing the l band measurements and will give both p and l band data to test inversion schemes for estimating geophysical parameters like rzsm. RFI measurements at the experiment site have been conducted. As a result of these measurements, IT is determined that the spectral band having frequency ranges of 490-529 MHZ, 691-720 MHZ and 781-850 MHZ are quiet enough to conduct a passive experiment. A p band radiometer that is capable of measurements in these three frequency bands is presently being designed. The RFI measurements are for a ground-based experiment. Aircraft RFI is more extensive and will require a more versatile radiometer. IT is proposed that during the period preceding the summer of 2019 a GW student will learn how to operate the comrad system and learn how to calibrate the h and v radiometers. This student, together with the PI, will be prepared to participate in the 2019 field tests. IT is anticipated that the p and l band radiometers will be located between a bare and a vegetated field. GW will also make dielectric measurements of the vegetation over the growing season. IT is also anticipated that the vegetation chosen will have sufficiently large biomass to observe differences between the p and l band microwave responses. P VS l band results could then demonstrate a superior ability of p band signals to penetrate vegetation.