OSSI is not a good comms engineer and need lots of studies. So this page might be messy until we know what they are.
Mononpole needs ground plane for imager half part of the Dipole.
Satellite is floating in the space with small size finte ground plane.
—> Go with dipole or j-pole if you want to have better communications. ( but diplole system will require balun and increase other mechanical complexity.)
And as the size of the ground plane of the cubesat is very small, Monopole antenna's radiation pattern will be similar to Dipole antenna's pattern and also its gain will be similar or even less than Dipole antenna.
Need a balun to interface signals from unbalanced → balanced or balanced → unbalanced
Some transceivers have balanced out and some has unbalanced out
Other parts are:
* Unbalanced = Single Ended / Balanced = Differential
RF stage Example) Differential Transmitter -> Balun A -> Filter -> Power Amp -> Balun B -> Dipole Antenna
* Balun A is 50 Ohm to 50 Ohm type (or 1:1 type) from balanced input ports to unbalanced output port
* Balun B is 50 Ohm to 75 Ohm type (or 1:1.5 type) from unbalanced input port to balanced output ports(as the impedance of the dipole antenna is 75 Ohm)
* Balun B requires high power rating!!!
When high power rating small sized balun is hard to get, we can solve the situation as below:
Cartesian coordinate system
Azimuth & Elevation
Place the antenna in the coord. system
* The PCB material determines the dielectric constant * The height of the PCB is very important.
If you design a RF system that transmits morse code with CW signal, you need to know the data rates.
To set PLL Loop filter Bandwidth, and other filters BW to efficiently set your system, you need to know the data rates.
But when it comes to morse code we go by the WPM (words per minute) unit. and to convert WPM to bps (bits per second), we use
1 WPM = 3.984 Hz (4 Hz)
And to convert bps to Hz
1 Hz = 2 bps, 1 bit is a half of the period
ex) 12 WPM = 48 Hz = 25 bps
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