Waveguide Slot Array Simulation seconds The 10-element model is built by using the single slot model and applying a single Copy operation to create the other 9 array elements. The slots are positioned periodically at the points where surface currents would otherwise be longitudinal, at the upper side of the waveguide, one guide-wavelength apart. 27 dBi Gain, 34.75 to 35.25 GHz, Ka-Band, Weather Resistant, WR-28 Slotted Waveguide Array Antenna. Slotted waveguide antenna array. The standard slotted waveguide antenna is designed following Elliot's modified design procedure. Elliot's modified design procedure not only takes into account the effects of mutual coupling from the neighboring slots in the array but also the internal higher order modes that are scattered off adjacent slots. The models of the Slotted waveguide antenna have been built and analyzed and agree well with results reported from 1. Montesinos Ortego, 'Contribution to the design of waveguide fed compound slot arrays by means of equivalent circuit modeling' 2.

This example shows how to analyze the performance of a slotted waveguide antenna.

Define parameters and Create a slotted waveguide

Longitudinal Linear Traveling Wave Slotted Waveguide

The array consists of radiating slots of different electrical lengths. Due to inherent property, each of them will resonate at their own individual resonance frequency. If the slot length and positions are chosen in such a way that the lower cut-off frequency and higher cut-off frequency of the nth slot overlaps with the higher and lower cut-off frequencies of the (n-1)th and (n+1)th slots respectively, then the complete array is expected to give a wide band response resulting in log-periodic dipole array. Slot Offset on broad wall slots are parallel to the waveguide centerline and they are blocking the transversal current components on the waveguide's broad wall. The polarization of these slots is vertical when the waveguide is held parallel to the ground and the transversal current component is zero on the centerline of the broad wall, however, if one slot moves closer to the narrow walls, the transversal current component increases. Therefore, the radiation amplitude of these slots increases as they move away from the centerline and that is why they are called offset slots. This is the most widely used slot type and this design is taken from [1].

Plot Reflection Coefficient

Plot the reflection coefficient for this antenna over the frequency band of 10GHz to 12GHz and a reference impedance of 50 ohms.

Radiation pattern

The most significant effect to be considered in the design process are internal and external mutual coupling between slots. The internal mutual couplings are caused by the partial reflections of the incident electromagnetic wave from succeeding slots in a waveguide. These partial reflections cause a considerable displacement of the EM field inside the waveguide.

Create custom slots in waveguide

a) Transverse Slots array

Transverse slots result in a very high value of their normalized resistance and they cannot be matched to the characteristic waveguide impedance. So, they have no practical importance.

b) X shape slots creation

The cross(X) slots can generate a circular polarized wave with a good axial ratio performance. The slots are oriented to form an orthogonal pair of slots which eventually generate a circular polarized wave. The theory of cross slots also suggests that the slots should be ideally equal to half of the free space wavelength.

Conclusion

The models of the Slotted waveguide antenna have been built and analyzed and agree well with results reported from [1].

References

Waveguide Slot Array Design

1. Montesinos Ortego, 'Contribution to the design of waveguide fed compound slot arrays by means of equivalent circuit modeling'

Slotted Waveguide Array Antennas

2. Zunnurain Ahmad,'Design and Implementation of Quasi Planar K-Band Array Antenna Based on Travelling Wave Structures'

Slot Waveguide Array