Recent content by thatsmessedup

Yep, the unit vector should be negative since the cross product points inward. It also makes sense because a resistive wire should have an inflow of electromagnetic power and the divergence of a vector represents outflow. Thanks for your help!

Right on! Thanks for the math help and I guess its not so bad after all.

Lol... Its been a few years since I've needed to do cross products on cylindrical coordinates. I wish I could remember how to do them. My EE notes look more like hieroglyphs at this point.

I think I'm rusty with my math skills. It all makes sense that there should be divergence in the center of the conductor as this is where all the Poynting vectors point. I need to whip out my old notes. I am assuming that J dot E is uniform in the cross sectional area of the wire. So, if I get...

At the center of the wire, the H field is 0 and so ExH is zero, hence the divergence is also zero.

According to equation (2.33) divergence of the Poynting vector or the outflow of electromagnetic power is equal to the stored magnetic field, stored electric field and ohmic losses. My contradiction is the following: Inside a steady state DC current carrying wire, there will presumably be a...

I tried different hand positions and there was no difference.

No I have not made a schematic, but I really thought the cap would make the fob do the magic. There are still many things that can be going on here. Possibly taking out the battery removed quite a bit of metal from inside the loop that is supporting the antennas resonance. At this point it would...

Gave it a try with a 100[uF] tantalum capacitor on the terminals. Not a single blip from the HackRF.

I think adding the capacitor will make it work. One last thing I tried was smaller leads but I think they were still to long. The wavelength at 432[MHz] is about 70[cm] so the leads would need to be much smaller than that to have a chance at sourcing power in a timely manner to be transmitted...

That makes a lot of sense. Maybe I can give this a try at some point but right now I don't have one of those on hand. Thanks!

Here are some closeups of the two major chips on the PCB.

This is the power supply I'm using.

I cranked up the current limiter and also tried a different variable power supply with no luck. I can't imagine that the grid is anything more then to make sure the battery is touching.