RF Jamming System: (An Educational/Theoretical Examination of Electronic Prevention and Countermeasures)

Generally, the method most people use, a Faraday shield, works very well, but I have found that people often forget to put the key into the bag, and at that point, they are vulnerable. How I protect my vehicle from relay attacks: I Understand this is illegal in many countries; I am only posting it here as an example of using technology to protect yourself from attackers and for all to understand that this is an educational exercise.

I started to look into the possibility of allowing the protection to be more active. The use of active prevention would mean jamming the signal. Since the frequencies for wireless fobs are 315Mhz and 433Mhz, I decided to build a low-frequency jammer that 315Mhz and 433Mhz; could prevent attackers from using a relay attack to open my door and start my vehicle. To find out the power level of my fob, I used a spectrum analyzer to find the frequency and measure the power level. I did not have to copy the code-plug signal because I was not looking to be that granular; ah yes, the code-plug, this is how many fobs can be on the same frequency, and yet only one vehicle is triggered by one fob, the code plug is programmed into the fob to provide a digital signal that the car recognizes as the fob assigned to the vehicle, since I am jamming the frequency as a whole I did not care about the code plug. At this point, here are the central components ?and purposes of the Jammer:

1)?????Frequency Generator: It generates a signal at the same frequency (315 – 433 MHz) as the target frequency. The generated signal is usually more substantial than the legitimate signals in the area, effectively overpowering them.

2)?????Amplifier: Increases the power and range of the generated signal. The amplifier ensures that the jamming signal is strong enough to interfere with the legitimate transmissions in the vicinity.

3)?????Antenna: The Jammer needs an antenna to transmit the amplified signal. The antenna radiates the jamming signal in the desired direction, covering the intended area with the disrupted signal.

4)?????Power Source: The Jammer requires a power source, typically a battery or power adapter.

Here is how such a device would look in the schematic format:

There are other schematics online, but this was the one I used for my system (Note that it took some tuning, but it worked pretty well in the end. The data input is where your code plug signal would go, but since I am interested, we will generate a signal with a continuous wave. Replace L3 with an RF coupling transformer to the amplifier. The amplifier will then increase the signal to a desired power over the fob's transmission. Such an amplifier would look like this:

The RF Amplifier circuit will provide adequate amplification, but there may be better systems on the Internet; this was just the one I chose to use. The RF input connects to the coupling transformer from the RF signal generator. The following antenna systems worked for me.

There you have it; how I protect my vehicle from relay attacks, I Understand that this is illegal in many countries; I am only posting it here as an example of using technology to protect yourself from attackers and for all to understand that this is an educational exercise.?