Property 'SlotSpacing' of waveguideSlotted doesn't work as expected

Hi, I'm using antenna toolbox to create slot array antenna these days.

And I am trying to give different slot spacings for each slot.

For example, I want the longitudial space between the first slot and second slot to be 0.0959(95.9 mm) and the space between the second and third slot to be 0.144(144 mm).

(By the way, until now, I only found slotted waveguides examples with single value of 'SlotSpacing')

clear;
close all
l_s = 61.2e-3; %Slot length
w_s = 6.5e-3;  %Slot width

% Slot offset (transverse) from the center of the waveguide
offset=[0.001599626
0.003822386
0.006529686
]';

% Slot spacing between slots
spacing = [0.095939738
0.144466676
]';

r = antenna.Rectangle('Length',l_s,'Width',w_s);

ant1 = waveguideSlotted('Length', 1.4,'Width',86.36e-3, 'NumSlots',3,...
    'Height', 43.18e-3,'Slot',[r r r] ,'SlotToTop',0.1,... 
    'SlotSpacing', spacing,'SlotOffset', offset,... 
    'FeedHeight',31.6e-3, 'ClosedWaveguide',1,'FeedOffset',[-0.3703 0], ...
    'FeedWidth',0.002,'Tilt',180,'TiltAxis',[1 0 1]);
figure
show(ant1);

The code runs without any error with the number of spacing entries one less than the number of slots.

However, when I run the code, the antenna is created as follows:

The space between the 1st and 2nd slot is 95.9mm, as expected, but the space between 2nd and 3rd slot is 193mm, not 144mm (not as designed). This keeps happening no matter what number I put in the second entry of 'SlotSpacing'.

I hope anyone can help me with this problem.

Thank you in advance.

Answer 1

[Angelo Yeo]

Hi Jaehoon,

1) First of all, the R2023a release does not officially support non-uniform slot spacing for waveguideSlotted. See that the data types is set to a double scalar not a vector.

There may be undocumented features for R2023a release but there is no guaranteed way of working for undocumented features.

2) However, it's worth checking out the possibility of bug. Can you create a technical support request so that we can handle the issue officially? You can click "report bug" button in the webpage below. Our technical support team will reach out to you via email.

https://www.mathworks.com/support/contact_us.html