Progress as of March 3, 2014
-Chose Wireline (F Antenna) approach. It is simpler to design and to make smaller.
-Use quadrature network to couple two F antennas to create a left-hand circularly polarized (LHCP) signal.
-Geoforce
currently uses an Antenova F antenna for the GPS signal (1575 MHz). By
adjusting the length of the copper, we can achieve a higher
frequency (1614 MHz).
Quadrature network
-Turns an input signal into two signals that are 90º out-of-phase with equal power.
-Includes a 50 ohm resistor in order to terminate reflections.
Progress as of April 20, 2014
-Showed that it is possible to tune an Antenova A10204 GPS antenna from 1575MHz to the desired frequency of 1614MHz.
.-Repeated earlier procedure in order to prove that the antenna will resonate at the desired frequency with little to no major modifications.
Antenna Patterns (Azimuth)
Antenna Patterns (Elevation)
Design
- two linear antennas mounted perpendicularly driven by a quadrature hybried coupler.
- Mounting perpendicularly forces the electric fields to be perpendicaular to each other.
- Driving them with the hybrid coupler forces the signals to be 90 degrees out of the phase.
- The combination of the perpendicular electric fields and the 90 degrees difference creates a circularly polarized signal.
Manufacturing and Testing
- PCB
Final PCB Design
*Using PADs layout software the above PCB was designed.
* The main specifications were the following:
- Placing the parts on the correct locations to have a left hand circular polarization
- Set the traces to the right width to have a impedance of 50ohms.
- Manufacturing
* Soldering antennas and hybrid coupler to the boards.
* Board to be designed in the second semester, based on antenna performance and how they interact with the boards.
* After placing the antennas and seeing their performance, an impedance matching needed to be done for them
- Testing
* Using network analyzer and antenna chamber in communications lab, the follwing will be tested:
- Gain
- Antenna Pattern
- VSWR
Linear Design Antenna (elevation) cone to design
Linear Design Antenna (azimuth) cone to design