Abstract

High-Isolation SP16T Switch For Use With A UHF Radar

Lynsey Metz and Cameron Lewis, Center for Remote Sensing of Ice Sheets, University of Kansas, Lawrence, KS, 66045

UHF radar is used for mapping near-surface accumulation ice layers in fine resolution.  While single-channel systems operate well over dry ice, multiple channels will improve performance of the radar over high-clutter areas by enabling the use of clutter rejection algorithms during the data processing stages.  Furthermore, it will also allow for the creation of 3-D tomography images of the ice layers.  This switch should accommodate up to sixteen RF channels while maintaining a high level of isolation to reduce interference.  In addition to this, points of consideration during the design process included the target operating frequency (500-950 MHz), minimizing insertion loss, and maximizing return loss for best efficiency.   The primary logic components of the switch included one SPDT switch connected to two SP8T switches, which were connected to the RF channels.  The printed circuit board of the device was designed in Altium Designer and manufactured by Sierra Proto Express.  A network analyzer was used to measure the return loss, insertion loss, and isolation of the switch.  The SP8T switches were found to be unsatisfactory; however, the SPDT switch performed well.  The PCB will be redesigned with different SP8T switches that will have external leads to allow for easier and more accurate installation.  Once populated, the new board will then be re-tested.  When the switch meets performance expectations, it will be ready for use with UHF radar for collecting data over Greenland and West Antarctica.