1. Slotted Waveguide Antenna Generalized Design from 1-70 GHz
Anil Kumar Pandey

2. Slot array antenna Synthesis using python Script
Array Antenna Design Flow in EMPro
Linear waveguide Slot array modeling in EMPro using parameterize variable for all components
Slot array antenna Synthesis using python Script
Calculation of antenna design parameters
Changing these parameters in EMPro GUI hence Changing Antenna CAD file as per specified Frequency
Setting FEM Simulation parameters
Starting FEM Simulation
Input Parameters
Operating Frequency
Number of Slots
Simulated Data

3. How a Waveguide Antenna Works
Slotted antenna arrays used with waveguides are a popular antenna in navigation, radar and other high-frequency systems.
A waveguide is a very low loss transmission line. It allows to propagate signals to a number of smaller antennas (slots). Each of these slots allows a little of the energy to radiate. Slot impedance and resonant behavior for a single slot are dependent on slot placement and size. Its exceptional directivity in the elevation plane gives it quite high power gain. The slotted waveguide has achieved most of its success when used in an omnidirectional role To make the unidirectional antenna radiate over the entire 360 degrees of azimuth, a second set of slots are cut in the back face of the waveguide. When looking straight at the face of the waveguide you will be able to see straight through both slots. Unfortunately, unless a lot of slots are used, the antenna becomes more like a bidirectional radiator, rather than an omnidirectional.

4. Linear Array Sketch Parameters of waveguide slot array design
Slot to Top
Parameters of waveguide slot array design
Slot length
Slot Offset
Length
Slot Width
Distance from port
Wg_a

5. Various Linear Array Combinations
2.44 GHz
64 slots
32 slots
N : No of Slots Variation
(F : Fixed)
13.2 GHz
16 slots
30 GHz
No of slots and Frequency are two variable input parameter . Varying these two parameters many combination of array antenna can be designed
60 GHz
F : Operating Frequency
(N : Fixed)

6. Slot Array Design Formulas
lam_zero=300/FGHz # Free space wavelength
WG_a= (lam_zero/2)+(lam_zero*0.2) # Auto calculation of broad (a) dimension of waveguide
WG_b = WG_a/ # Height (b)of waveguide
PI=3.14
lam_cutoff=2*WG_a
lam_guide=1/sqrt(((1.0/lam_zero)**2)-((1.0/lam_cutoff)**2))
# Slot offset
G_2_slot=1.0/Nslots
New_G1=2.09*(lam_guide/lam_zero)*(WG_a/WG_b)*(cmath.cos(0.464*PI*lam_zero/lam_guide)-cmath.cos(0.464*PI))**2
New_Y=G_2_slot/New_G1
Soff=(WG_a/PI)*sqrt(abs(cmath.asin(New_Y)))
# Slot Lenght
Slot_wl= *G_2_slot** *G_2_slot** *G_2_slot** *G_2_slot
Sl=lam_zero*Slot_wl
#Slot width
Sw=WG_a*0.0625/0.9
#Slot Spacing
Ss=lam_guide/2
# Distance from short ( end space)
S_top=lam_guide/4
#Estimated Performance
Gain=abs(10 * cmath.log10((Nslots/2) * lam_guide/lam_zero)) #dB
Beamwidth=50.7 * lam_zero / ((Nslots/2)*(lam_guide/2)) #degree

7. Working Model
This is generalized example of slot array antenna from 1 GHz to 70 GHz. This example uses powerful feature of EMPro python scripting for slot array parameters calculation and parameterize feature of EMPro to create generalized example.
Open the project in EMPro
Double click synthesis script present in project
Enter desired operating frequency and number of slots
Run script, it will automatically calculate all design parameters, set parameters in GUI and modified CAD file as per specified frequency and launch FEM simulation
Other Tips
If you don’t want to launch FEM simulation , comment below two lines in script
#setupSimulation(FGHz-1, FGHz+1, 25 )
#return empro.activeProject.addSimulationDataToProject(autoQueue)

8. Array Antenna Performance at 2.41 GHz
WAN: antenna for 2.44GHz, or channel 7
Slotted Waveguide b WLAN antennas
Gain-9.69 dBi
Simulation time- 22Min 47 sec
Unknown Million
Memory – 400 MB (Iterative)

9. Array Antenna Performance at 6 GHz
Gain dBi
Simulation time- 32Min 41 sec
Unknown Million
Memory – 400 MB (Iterative)

10. Array Antenna Performance at 27 and 60 GHz
Gain dBi