SIW (Substrate-integrated-waveguide) antenna why using this?

[STINGERX]

i just read an article about a new type of transmission line called SIW or Substrate-integrated-waveguide, i understand that this is better then a rectangular waveguide mainly because there are no limitations of dimantion of the thikness of the SIW (on a rectangular waveguide 2:1).
but why is it better then microstrip and strip line?

also why there is no TM mode in SIW?

 

[biff44]

it is just a dielectric filled rectangular waveguide. there are te an tm modes

2:1 is NOT a required aspect ratio for rectangular waveguide. saying so would be like saying "I don't like coaxial transmission lines, they are all only 50 ohms!"

 

[STINGERX]

please read this:

Because there are vias at the sidewalls, transverse magnetic (TM) modes do not exist;

if everything works out, it looks like a dielectrically-filled rectangular waveguide, with reduced height compared to the "normal" 2:1 width:height ratio. Reduced height is no big deal, it just reduces the impedance the wave sees (increases capacitance/length).

from this website:
https://www.microwaves101.com/encyclopedias/724-substrate-integrated-waveguide

i'm very Confused

 

[cstwonder]

because current don't pass in the wall of the via because of this interruption of space between them

 

[Terminator3]

Do you still interested in SIW? There are some papers on SIW within FR4 at >20GHz frequency, slot antennas, resonators, filters.
I think SIW can be used to filter out lower harmonics of harmonic oscillator. Just make SIW waveguide, wich accepts only >1.6*Fo frequency, then only 2*Fo can pass. Or make for higher harmonics N*Fo. Losses must be smaller than microstrip bandpass and unwanted freq. attenuation must be bigger than quaterwave stub technique (i think so).

 

[cstwonder]

Now I am intrested in SIW cavity backed slot antenna more than filter it's more complicated then SIW filter

 

[Terminator3]

Do you mean slots in SIW itself? I guess you talk about simulation complications. I think prototyping can help.
Currently i want to learn SIW by ordering some SIW test PCBs:
1) make pcb layout with long SIW, put different slot configurations on it's top (without green mask!)
2) order board (online pcb manufacturer, etc.)
3) choose slots you want to examine, solder copper foil above unused slots
4) after examining some slot configuration, put copper foil above them, and check other slots by unsoldering foil on top of them.

In my case i want to try SIW filter: i make long SIW with different shapes on ground plane (removed copper). By adding foil i can choose different shapes and check filter performance. You can order prototypes too, and then alter your simulations in right direction.