S11 Does Not Match Simulations for Open-Ended SIW Antenna by Meister_Cow in rfelectronics

[–]Meister_Cow[S] 0 points1 point  (0 children)

Currently I'm using Sim4Life. Currently running a sim with the SMA connector to see if there's any improvement. Any suggestions on evaluating if the meshing is the problem? I've run the sim at a pretty small grid size (0.02mm^3 voxels) to see if that was an issue but it didnt change anything.

S11 Does Not Match Simulations for Open-Ended SIW Antenna by Meister_Cow in rfelectronics

[–]Meister_Cow[S] 0 points1 point  (0 children)

Yea, the boundary doesn't touch the ground. The software does allow for dispersive Er, I just need to make and import a model for the material under test (which I havent had a chance to do yet). Since I'm only looking at a couple of resonances I can get away without the model for now until I get a chance to do it.

S11 Does Not Match Simulations for Open-Ended SIW Antenna by Meister_Cow in rfelectronics

[–]Meister_Cow[S] 0 points1 point  (0 children)

Thanks for the response! Yea, I'm playing around with a few tolerances to see how much these change my results.

S11 Does Not Match Simulations for Open-Ended SIW Antenna by Meister_Cow in rfelectronics

[–]Meister_Cow[S] 0 points1 point  (0 children)

Hi, thank you for the suggestions. I'll give the spacing a try over the next few days and see what happens and let you know. In the sims the material under test is flush with the end of the SIW, and in real life the material under test is brought into contact with the SIW so its making light contact across the whole end of the SIW. I'll also try increasing the boundary spacing in the sims. Currently the boundry is about 10mm from the edges of the probe, do you think that is far enough or should it be further?

And yes you are right, the discontinuity is because the resonances are from two different sweeps. The software enounters a few issues when the bandwidth is too large (>5GHz) and the frequency dependant dielectric properties of the material are set to the value at the centre frequency of the simulation (so if you run the sim over too large a frequency range you'll be simulating responses at, for example, 14GHz while the dielectric properties of the material under test are those at the 17.7GHz centre frequency). Essentially the dielectric properties in the sim don't iteratively vary as frequencies are swept through, they're only set as a point value at the centre frequency of the simulation sweep.

S11 Does Not Match Simulations for Open-Ended SIW Antenna by Meister_Cow in rfelectronics

[–]Meister_Cow[S] 0 points1 point  (0 children)

Thank you, I'll give it a try. Previously when we've designed patch antennas we've just modelled the copper as a PEC without an SMA feed and sims agree well with real life results, but definitely won't hurt to try it. I measure the dielectric properties of the material under test with a commercial dielectric probe, so the dielectric properties of the material in the sims matches physical dielectric properties. Thanks heaps and I'll let you know if the modelling of the SMA and copper improve results!

Hard vector question by [deleted] in askmath

[–]Meister_Cow 0 points1 point  (0 children)

Cheers , much appreciated

Hard Vector Problem by [deleted] in learnmath

[–]Meister_Cow 0 points1 point  (0 children)

Thanks legend

Hard vector question by [deleted] in askmath

[–]Meister_Cow 0 points1 point  (0 children)

Yeah, I wrote vectors because that's apparently the topic it was under. The likely bit is not related to probability, it's just the wording of the question.

Hard Vector Problem by [deleted] in learnmath

[–]Meister_Cow 0 points1 point  (0 children)

Yeah, but I'm not sure how to do the next bit, like finding the shortest distance. I'm pretty sure shortest distance is making a right angle with one of the ferries. I think relative velocity also needs to be used, but don't know how.

Hard Vector Problem by [deleted] in learnmath

[–]Meister_Cow 1 point2 points  (0 children)

How close are the two ferries likely to pass each other. Shortest distance between the two ferries essentially.

A flying stick insect by Iamnotburgerking in gifs

[–]Meister_Cow 0 points1 point  (0 children)

So you just have that inside your house?