microstrip antennas with slots

I have seen in many publications that with inserting slots in a microstrip antenna the resonance shifts to lower frequences.Does anybody knows which is reason for that.I think that it has to do with surface waves but is there anybody who can explain it me more specifically.

thank you in advance.

peterpsomos

peterpsomos said:

I have seen in many publications that with inserting slots in a microstrip antenna the resonance shifts to lower frequences.Does anybody knows which is reason for that.I think that it has to do with surface waves but is there anybody who can explain it me more specifically.

thank you in advance.

peterpsomos

Click to expand...

Dear peterpsomos!

My explanation is that the slots will extend surface electric current paths at the patch. Just play with rectangular patch operating at fundamental mode in simulator and insert proper slot - look for vectors of currents. Another explanation can be made by distribution of electric field under the patch but currents are more telling here.
For further reading the book Kin-Lu-Wong:Compact and Broadband Microstrip Antennas is recommended

Cheers,

Eirp

I think small problem with text editor, why are p@tch (patch) all replaced by fix?


Element7k

eirp said:

Dear peterpsomos!

My explanation is that the slots will extend surface electric current paths at the fix. Just play with rectangular fix operating at fundamental mode in simulator and insert proper slot - look for vectors of currents. Another explanation can be made by distribution of electric field under the fix but currents are more telling here.
For further reading the book Kin-Lu-Wong:Compact and Broadband Microstrip Antennas is recommended

Cheers,

Eirp

Click to expand...

When we extend the current path of surface waves the microstrip antenna acts as its bigger, because although it has the same physical length, it has bigger electrical length?

Element7k said:

I think small problem with text editor, why are p@tch (fix) all replaced by fix?


Element7k

eirp said:

Dear peterpsomos!

My explanation is that the slots will extend surface electric current paths at the fix. Just play with rectangular fix operating at fundamental mode in simulator and insert proper slot - look for vectors of currents. Another explanation can be made by distribution of electric field under the fix but currents are more telling here.
For further reading the book Kin-Lu-Wong:Compact and Broadband Microstrip Antennas is recommended

Cheers,

Eirp

Click to expand...

Click to expand...

This is really funny

We have p@tch antenna and also another kind of p@tches..
It was made by autocorrector

@peterpsomos: yes, electrical length for currents is then bigger

I only noticed the autocorrection recently when someone ask for examples of Fix antenna?!! 8O I wasn't very sure what a fix antenna is so I asked and realised it was a p@tch antenna! :lol:

Also, I noticed one comment that peterpsomos made. He talked about extending the current path of "surface waves". Does anyone think that this is in error? We do not want surface waves to propagate in antennas?! Could "surface currents" be a more appropriate term to use? :?: Surely, phase velocity can be used to explain why resonance frequency is lower with slots antennas? :?: :!:

Cheers,
Element7k

eirp said:

This is really funny

We have p@tch antenna and also another kind of p@tches..
It was made by autocorrector

@peterpsomos: yes, electrical length for currents is then bigger

Click to expand...

I was wrong to talk about surface waves.What i really wanted to say is surface currents.Sorry for that.Anyway, i think i understood the reason why resonance shifts to lowers frequence in microstrip antennas with slots.Actually for the same reason resonance shifts to lower frequencies when we meander a microstrip antenna.

Thanks anyway

peterpsomos.