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- Adjusted solder mask clearance - Changed trace width for JLC stackup Co-Authored-By: Valles1 <134664903+Valles1@users.noreply.github.com>
…turnstile antenna
have to readjust the pads now : (
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Introduction
The OreSat Turnstile Mezzanine Board was refactored for use on this iteration of the PROVES Antenna board. The feed line architecture with the QBA-07+ power splitters/combiners was adopted from the OreSat Turnstile Mezzanine Board into the v3 Antenna Board.
The sensors from the previous version of the PROVES Antenna Board were removed.
The Burnwire Footprint changed to a resistor footprint.
90 degree phase shift trace length calculation
The wavelength in air of 437.5 MHz is ~685.23 meters. However, according to the image above, the wavelength changes based on the effective electric permittivity.
The width of the trace was found by using the JLCPCB impedance calculator. The single ended coplanar value was used instead of the single ended non-coplanar since there are ground vias running along side the traces. The height was taken as the thickness of the dielectric.
By plugging the values into the equation, the wavelength of a 437.5 MHz signal on the PCB is ~390.45 mm.
A quarter wavelength is used to shift the signal by 90 degrees. By taking our new derived wavelength, the quarter wavelength trace should be ~94.59 mm.
Other Lengths
The OreSat Canted Turnstile PDF as well as the mezzanine board schematic was used as the main source to the following decisions about the lengths of the other traces.
The length for UHF-SHORT on this antenna board is 39.1782 mm. I believe this is an acceptable length since it is below the wavelength of 437.5 MHz. This length was added to the 1/4 wavelength to get a phase shift of 90 degrees resulting in the 180 degree and 270 degree signals.
The length between the QBA-07+ and the landing pads was 25.24 mm. This value was chosen so that it would be easier to measure and cut the antenna elements at whole numbers instead of at decimal points.