My Biggest Discovery

As I’ve studied RF and Microwave systems during my research, I’ve realised something huge. Something, that I wasn’t able to find in any books or journals:

Engineering is an applied science.

What does that mean?

Well it basically means that, Engineering’s true purpose is to apply a theory, a scientific truth, – or sometimes just trial&error- to achieve something: To make something work, function, increase productivity, decrease the cost, reduce the size or improve an aspect of something. Well, it’s kinda obvious and can be considered too simple for being a discovery. I think it is not a discovery at all but what I want to point out is:

 it is necessary to get some results, to implement something, to fabricate something, basically, it is nesessary to do something.

So what I’m gonna do?

I’ll try to fabricate most of the RF/MW components, then measure them and analyse the results, to further improve them. It would surely take at least one iteration of designs to achieve the best performance, but also the experience and insight gained from such an action would be invaluable.

“In my book, experience outranks everything.” – Captain Rex

To begin with, I’ve drawn several PCBs which contain several passive microstrip structures for 0.8mm FR4 substrate using simple hand calculations without any kind of simulation. If the theory is solid, and the approximations are within tolerable limits, my measurements would be in parallel with the expectations. Thou I’ve several issues

  • Dielectric constant of FR4 can vary at each batch production, as well as it varies with frequency
  • The roughness or variation of microstrip line widths, or the substrate thickness itself
  • The soldermask or surface finishing is not used for calculations, thou would it effect any RF or microwave properties of the devices?

It is easy to enrich this list further. The on-hands experience of this “design-make-test” cycle may both be fruitful, as well as I hope to kindle some enthusiasm for making such things for yourself. There are many passive RF devices which are easy to fabricate using microstrip structures. Also, using the same type of substrate for many designs as you will have more experince working with that substrate and get used to its RF characteristics. Moreover, it might be necessary to implement many of this devices on the same substrate one day. So, it might be wiser to use only one type substrate. I would advice using a cheaper type thou, as my goal is to get experience.

Some portion of my initial PCB drawings – Do you recognise any of these structures?

Conclusion

To sum it up, the fundamental of RF/Microwave Engineering is to practice this form of magic. I call it magic because it is hard to visualise the Electromagnetic waves and fully understand the propagation of waves in different mediums. On the other hand, Smith Chart is another form of magic, which we spend so much time to understand. I personally believe it’s the reason of header “Black Magic Design” on the Smith Chart.

I think “design-make-test” cycle is extremely important to become a good RF/MW engineer. Most of the time, you’ll need to get a device which suits your needs. You’ve learned many tools to help you achieve this during your B.S. or M.Sc. or even Ph.D. Now, you need to practice it, and it will become well-known to you. You’ll realise that, without experience, even the simplest structures won’t satifsy your needs at first shot. You can easily do many things with micro-budgeted projects.

Coming up next…

So, as this page is going to be about RF and microwave engineering related stuff, I’ve plenty of things I want to add in the near future. I’ll probably introduce you guys some of the passive devices fabricated for us. I’m also planning to use videos or pictures to help you guys visualize and track the progress easier. Plus, it would be more fun that way!

Hope to see you guys in the next post,

Categories: Microwave/RF

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