Edited with previous suggestions

I work for a company that builds (redacted for privacy), and a big company lent us a special GPS anti-jamming device, and I am in charge of implementing and testing it.

I already implemented the anti-jamming device and I am in the process of building a test GPS jamming device, there are plenty of buying options on the internet but I am going to build my own, as this interference research is also the topic of my masters thesis.

All the tests will be conducted at low transmission power at a remote location, provided by my company, to avoid any interferences. The amplifier used in the project has a low-gain mode and we also have plenty of attenuators available in case needed.

As this is my first RF design ever, this step will be just to try to transmit a square wave with duty cycle of 50% at a frequency of 1575Mhz. (i believe that that can accomplish jamming).

I want help validating the idea and the schematics seen below, I use a MCP1703 as a voltage regulator for both 5V and 2.8V, a CVCO55CC for generating 1575Mhz and a MC13851 amplifier, their datasheets are found below, I also based my designs on each of their evaluation boards. Also a DC source will be used in the place of the battery sometimes.

I also need to know if there are any tips in RF for then trying to draw the PCB layout.


Schematics 2

Schematics 3





https://www.nxp.com/docs/en/quick-reference-guide/MC138511575QSG.pdf (evaluation board)



https://www.crystek.com/microwave/spec-sheets/vcoeval/CEVAL-033_055.pdf (evaluation board)

  • 1
    \$\begingroup\$ As a minimum, replace those ? with component designator numbers, so that people can discuss the circuit. Your reference voltage is not. Show non-polar caps as non-polar. Draw an RF path as a straight line left to right, so the series components in it go left-right, and components in shunt to it go up or down. Have more positive voltages to the top of the page, so for instance L? (the 270 nH one, now you see why we want ref des numbers) will go up to the power supply. Yes, you can connect a 50 ohm antenna to a 50 ohm amplifier output. \$\endgroup\$
    – Neil_UK
    Jun 21, 2022 at 11:01
  • 1
    \$\begingroup\$ Your voltage reference is a pot-down from the rail. 22p and 1p capacitors are not going to be polar. \$\endgroup\$
    – Neil_UK
    Jun 21, 2022 at 13:59
  • 1
    \$\begingroup\$ I can see the trimpot. The voltage into that is from your battery, which is not stable, so the output will not be stable (with temperature, with battery state etc). The input to the pot should be from a voltage reference, or at very least a voltage regulator. You cannot obtain 22 pF polarised capacitors. You will use a chip ceramic, which will be non-polar, even if the voltage across it will be uni-polar. Then, when you come to make the board, it will not matter which way it is assembled. In contrast to electrolytics, of which you appear to have none, which need a polarity marker on the board. \$\endgroup\$
    – Neil_UK
    Jun 22, 2022 at 5:43
  • 1
    \$\begingroup\$ @RicardoSilvestre - Hi, I recommend you add a short comment here, explaining what changes you just made in your latest edit and how they address any points raised in the comments above. Thanks. \$\endgroup\$
    – SamGibson
    Jun 22, 2022 at 12:20
  • 1
    \$\begingroup\$ I have measured the output of a car plug-in jammer (of unknown origin) using a spectrum analyser. It showed a surprisingly well-defined jamming signal spread around the GPS frequency - it did appear to be more sophisticated than a simple RF oscillator, probably because some GPS devices can detect and reject single-frequency jamming. So I suggest you test the anti-jamming technology using some real jammers, not just your device. \$\endgroup\$
    – jayben
    Jun 22, 2022 at 12:32


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