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RECEIVER ANTENNA
  
 


The Martian terminal receiving antenna is a patch antenna type. A patch antenna is beneficial in this case because of its light weight, low volume, and thin profile. These elements allow this antenna to be implemented in MPS devices ranging from a simple handheld device for Mars colonists to probes navigating the surface. Additionally, it can be implemented on the same PCB as the other circuitry allowing for easy fabrication and decreased cost.

Figure 1 shows the antenna design that was built and measured. The antenna is designed to operate at 2.1GHz. This frequency choice allows substantial padding around currently used radio astronomy bands and is removed from the high absorption peaks of carbon dioxide, nitrogen, and argon, the major gases in the Martian atmosphere.

  
 


Figure 1: Patch Antenna Dimensions

 
  The antenna is built on a 1.28mm thick Rogers Duroid 3006 substrate with a relative dielectric constant of 6.15. The larger dielectric constant allows the antenna to be smaller, but at the expense of bandwidth. The sides of the rectangle are approximately equal to half a wavelength, and the top left and bottom right corners are cut so that the antenna will be left-handed circularly polarized. This polarization state will allow the signal to propagate through the ionosphere with minimum effects from Faraday rotation. Finally, a micro-strip feed line with a stub was added to match the impedance to approximately 50 ohms. The antenna design was created and simulated in Ansoft Designer before fabrication. Figure 2 shows the completed antenna.
  
 

Figure2: Fabricated Patch Antenna
Figure 2: Fabricated Patch Antenna
  
 

 
 


References

C.A. Balanis, Antenna Theory and Design, Edition 2, New York: John Wiley & Sons, 1997, 466-472, 722-760.

R. Garg, R. Bhartia, I. Bahl, and A. Ittipiboon, Microstrip Antenna Design Handbook, Boston: Artech House, 2001, 253-314.

C. Ho and N. Golshan, “Radio Wave Propagation for Communication on and around Mars: Highlights of Parat I: Propagation Through Mars Environment,” Communication Systems and Research Section, Jet Propulsion Laboratory, 1999. [Online]. Available: http://trs-new.jpl.nasa.gov/dspace/handle/2014/17651. [Accessed: October 30, 2008].

United Kingdom Radio Astronomy Network, “Radio Astronomy Frequency Allocations,” National Radio Astronomy Observatory, 2006. [Online]. Available: http://www.ukaranet.org.uk. [Accessed: October 30, 2008]