Hughes Network Systems Low Cost Satellite Antenna for Maritime Voice and Data Services

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Hughes Network SystemsLow Cost Satellite
Antenna for Maritime Voice and Data Services
Sponsor / Bill Whitmarsh Ph.D

• Group 3 / Steve Lui Robert Yang Yu-Hsiang Su
  Ryan Hung

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Agenda
Receiver
Software
Power Management

• 1 Design Patch Antenna
• 2 Switch Matrix
• 3 Receiver (Rx) Power Management
• 4 Control Software

Pin Diode Switch
Patch Antenna
Group 3
3
Tasks Patch Antenna
Reference Materials - Microstrip Antenna
Design Handbook (Artech House) Garg,
Bhartia, Bahl, Ittipiboon Prototype
Construction - Physical dimensions - Weight
specs - Materials Specs - L Band 1525 to
1665 MHz - Circularly polarized
Patch Antenna
Group 3
4
Tasks Patch Antenna
Prototype Construction - Physical dimensions
gt base diameter 12 gt
height 6 - Weight
specs gt Projected 10 lbs. -
Materials gt Smoked plastic dome
casing gt Metal base
Patch Antenna
Antenna Casing
Group 3
5
Tasks Patch Antenna

• Steps To Designing the Patch Antenna
• Choose e (dielectric permittivity) to gain a
  maximum bandwidth. We decided to use
  RT/Duroid5880 from Rogers corp.
• Choose this material because duroid is employed
  as the dielectric giving 3.8 bandwidth
• To further increase bandwidth we choose max
  thickness of this material offered at Rogers
  which is 1.25mm. Further increase in thickness
  will reduce the efficiency and the gain of the
  antenna.
• Once we find the height the optimum patch size
  can be found to resonate at 1.575Ghz 1.6GHz
• Other considerations is we need to find the input
  impedance to develop the power regulator and
  reciever circuit accordingly
• Antenna also has to be circularly polarized.
• Maximize bandwidth (bandwidth enhancement)

Patch Antenna

Group 3
6
Antenna Design
Objective To get circular polarization

• To get circular polarization, three things must
  be done.
• Split the signal in two equal parts
• Feed one signal to a horizontal radiator and the
  other to a vertical radiator
• Change the phase of one of the signals by 90
  degrees
• Splitting the signal in half can be done with a
  Wilkinson or similar splitter. If we build a
  patch with two feed points, we have created a
  vertical and a horizontal radiator. By creating
  the 90 delay in one of the signal lines and
  connecting each signal to one feeding pin of the
  patch, we built a circularly polarized antenna.

Even though this works, the splitter and delay
line take up valuable board space and also tend
to radiate and degrade radiation
pattern. Another approach is to see the patch as
a parallel RLC resonant circuit. What we have to
do is to build a patch with two resonant
frequencies and use the antenna right in between
the two resonances. A number of ways exist to
implement this, but cutting two corners off the
element, the so-called corners truncated patch,
is a technique widely used in GPS antennas.
(which is what we are trying to do)
This method also reduces the antenna to just one
feeding pin. The probe type feed is usually
seen in GPS antennas. PART TO ORDER PCB mount
SMA connector, Amphenol RFX 901-9895-RFX
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Antenna Design
Equations and Calculations for the Dimensions of
the Antenna We need resonance frequency
1.575GHz 1.6GHz Our thickness or height of the
material is 1.25mm with a dielectric value e of
3.38

Dimensions we get are 48.74mm x 73.88mm
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Antenna Design
Other Factors Input Impedance for the Antenna
(Impedance presented by an antenna at its
terminals) Typical impedance of a rectangular
patch antenna varies from 100 to 400 ohms. At
the resonance the approximate input impedance of
a patch is given by the equation below.
Input impedance (resistance) is reduced by
widening the patch.
is the dielectric constant
L length W width
Group 3
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RF PIN Diodes
Tasks Pin Diode Switch
Pin Diode Switch
Reference Materials - General RF design and
the PIN diode switchesMicrowave Engineering
(Addison-Wesley)Pozar
Group 3
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PIN Diode Switch Schematic
Switch Design
Group 3
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Basic Circuit Design
Switch Design

• Philips BAP51-02 Diode
• Operates up to 3GHz
• Low insertion loss
• Single pole
• Miniature design
• Affordable

Group 3
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Tasks
Reference Materials - Previous antenna project
documentation (Jeremy, HNS) Research about Basic
Stamp
Receiver
Software
Power Management
Group 3
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Goals for Week 4

• Finish research
• Finish designing
• - Circularly Polarized Patch Antenna
• - RF PIN Diode Switch
• - Receiver
• - Computer (Software/Controller)
• Order parts and circuit components

Group 3
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G - Chart
Define Project
Research ltPatch Antennagt ltPin Diode Switchgt
System Design
Order Parts
Hardware Fabrication
Software Development
HW/SW Integration
Testing/Revising
Final Presentation
Documentation
Week 1 2
3 4 5 6
7 8 9 10
Group 3