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I understand, from a previous question, that the generation and simulation of near-field microwave electronics is challenging.

Before doing a full simulation, is it possible to get a ballpark estimate for what a reasonable amount of microwave power is possible to generate in a small region (without enhancing it via a cavity)?

For example, what is the rough feasability of 1W of microwave power in a 1mm^3 region at 10GHz? It would be my first time trying something like this, and I want just a quick evaluation of people with more experience if this is a realistic goal.

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  • \$\begingroup\$ What is the meaning of power delivered to a volume of undefined impedance? Would a microstrip transmission line not suffice? \$\endgroup\$
    – Tim Williams
    Commented Aug 4 at 13:32
  • \$\begingroup\$ @TimWilliams, perhaps I'll write a new question to explain the details. But the context is: I was origionally considering a microwave cavity at 10GHz, and I wanted to see if I could produce the same field strength for a small region inside the cavity, in an open configuration without a cavity at all. I have a loose understanding that this should be equivalent to about 1W of microwave power in a 1mm^3 region -- but as you say, perhaps my estimate of power is not so clear. \$\endgroup\$
    – Steven Sagona
    Commented Aug 6 at 17:13
  • \$\begingroup\$ Are you asking specifically about generation, ie. Feed X watts of DC into a cubic millimeter, then some fraction of it comes out as microwaves? Otherwise, what’s the purpose of the word generate? The limitations will be purely thermal, not much to do with RF. It is insanely hard to cool down a cubic mm even if everything around it is metal. The imaginary generator would be fed power via solid copper, and RF would exit via a copper transmission line with minimum of dielectric. \$\endgroup\$
    – Kuba hasn't forgotten Monica
    Commented Aug 6 at 17:16
  • \$\begingroup\$ If you’re not generating the RF power, just passing it through dielectric, then 1W/mm^3 is not very much. Plenty of transmission lines do this day in, day out. So, is that what you are asking? You want about 1mm^3 of space, all of it presumably dielectric, right? There can be metal around it. Not even necessarily nearby - the cube can be inside a waveguide that’s pushing kilowatts out. So it looks like your question is sort of trivial, unless you can really explain what you mean. The lack of clarity makes it frustrating. You mean something - just say it, don’t save it for later. \$\endgroup\$
    – Kuba hasn't forgotten Monica
    Commented Aug 6 at 17:22
  • \$\begingroup\$ @Kubahasn'tforgottenMonica, well perhaps you can assist me in the correct word choice. Here's another description for clarity: if you imagine, for example, that I already have a microwave source, which is coupled in an SMA cable -- then my goal is to produce a certain field strength such that it corresponds to 1W of disappation of power from a standard SMA cable. \$\endgroup\$
    – Steven Sagona
    Commented Aug 6 at 17:22

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Microwave power cannot be "concentrated" on scales below its wavelength. To get to 1mm scale, your frequency should be about 300GHz, not 10.

Roughly speaking :-)

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  • \$\begingroup\$ Try and keep comments to discussion ideas and not calling people out. \$\endgroup\$
    – Voltage Spike ♦
    Commented Aug 5 at 3:48
  • \$\begingroup\$ @VoltageSpike Can you undelete my initial comment? It was addressing the same content as the current edit, so remains relevant context for readers. If it was worded improperly, that's understandable, but in that case an edit might suffice; but I also don't recall calling anyone out but rather the content so I'm a bit mystified by its removal. Otherwise, I'll replace it just as well. \$\endgroup\$
    – Tim Williams
    Commented Aug 5 at 5:06
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    \$\begingroup\$ This is true in the far field, with conventional optics, but is not true in general. Energy can easily be concentrated, in the near field, no cavity required: transmission lines work at arbitrarily small fractions of a wavelength. Rather, there's an upper limit (mode breakup) instead. A 1 mm cube region underneath a microstrip would make a fine TEM cell up to, say, 35GHz or so? \$\endgroup\$
    – Tim Williams
    Commented Aug 5 at 5:07
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    \$\begingroup\$ @StevenSagona, this is not a misinterpretation. You used the term "concentrated", which implies that you need 1W inside a 1mm3 volume, and nothing around. Similar to what an optical lens do in its focus. Maybe you need more academically-accurate formulations of what do you need or ask about. \$\endgroup\$
    – Ale..chenski
    Commented Aug 6 at 3:40
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    \$\begingroup\$ Fwiw I also always interpreted it as RF powe in the volume and =0 elsewhere. \$\endgroup\$
    – MrGerber
    Commented Aug 6 at 18:01

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