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

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

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.

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

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)

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/2 # 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=0.210324*G_2_slot**4-0.338065*G_2_slot**3+0.12712*G_2_slot**2+0.034433*G_2_slot+0.48253 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

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)

Array Antenna Performance at 2.41 GHz WAN: antenna for 2.44GHz, or channel 7 Slotted Waveguide 802.11b WLAN antennas Gain-9.69 dBi Simulation time- 22Min 47 sec Unknown - 0.2 Million Memory – 400 MB (Iterative)

Array Antenna Performance at 6 GHz Gain-10.48 dBi Simulation time- 32Min 41 sec Unknown - 0.3Million Memory – 400 MB (Iterative)

Array Antenna Performance at 27 and 60 GHz Gain- 11.43dBi