Analyze Electromagnetic Interference from Shielding Enclosures

Define Enclosure and Slot Dimensions

Define the enclosure and slot dimensions in meters.

enclosureLength = 220e-3;
enclosureWidth = 300e-3;
enclosureHeight = 140e-3;
slotLength = 2e-3;
slotWidth = 120e-3;

Create Shielding Enclosure

Create a box with shape.Box shape using the defined enclosure dimensions.

box = shape.Box(Length=enclosureLength, Width=enclosureWidth, Height=enclosureHeight);

Create another box with slot dimensions. Subtract the slot shape from the enclosure box shape to get the final shielding enclosure shape.

slot = shape.Box(Length=enclosureLength/2, Width=slotWidth, Height=slotLength, Color="r");
box.Transparency = 0.3;
[~] = translate(slot,[enclosureLength/2 0 -50e-3]);
boxEnclosure = box - slot;
[~] = translate(boxEnclosure,[0 0 40e-3]);
show(boxEnclosure);

Create Source Feed-Probe

Create a circular feed-probe using shape.Circle and performing extrude operation on the box enclosure. It spans from top of the box where the feed is attached to the slot.

feed = shape.Circle(Radius=0.8e-3, Center=[0.05 0], NumPoints=20, Color="r");
[~] = translate(feed,[0 0 -0.11]);
[~] = rotateY(boxEnclosure,180);
antShape = extrude(boxEnclosure,feed,Height=0.12);
[~] = rotateY(antShape,180);
show(antShape)

Create a custom antenna with the enclosure shape and visualize it.

ant = customAntenna(Shape=antShape);
[~] = createFeed(ant,[-0.05 0 0.11],20);
show(ant);

Analyze Enclosure Setup

Calculate E-H fields at a distance of 3m along the x-axis from the enclosure setup.

[E,H] = EHfields(ant,linspace(0.7e9,1.6e9,100),[3 0 0]');

Calculate the E-field magnitude.

Et = abs(E);
Et = sqrt(Et(1,:).^2+Et(2,:).^2+Et(3,:).^2);

Plot the E-field magnitude against 700 MHz to 1.6 GHz frequency range.

plot(linspace(0.7e9,1.6e9,100),10*log10(Et./1e-6));
xlabel("Frequency(Hz)");
ylabel("|E|dBuV/m");

Conclusion

As seen from the E-field magnitude plot across the 700 MHz to 1.6 GHz frequency range, electromagnetic interference is significant when the larger dimension of the slot is comparable to half-wavelength at the respective frequency.