1 Introduction
The characteristics of the Axial Mode Helical Antenna is investigated with Electro Magnetica Nu- merica version 1.7.0. The article reports the model and the results.
2 Helical Antenna
2.4GHz Band Axial Mode Helix Antenna is investigaed. The parameters of the antenna are shown in Table1. The overall view is displayed in Fig.1 The signal input port is coaxial cable with 120 Ohms which is corresponded to the antenna impedance.
| Helix Radius | 20 mm |
| Helix Height | 300 mm |
| Helix Pitch | 30 mm |
| Helix Wire Rad | 2.0 mm |
| Ground Radius | 62.5 mm |
| Ground Thickness | 2.0 mm |
| Coax Radius | 14.8 mm |
| Coax Pin Radius | 2.0 mm |
| Coax Length | 50 mm |
Figure 1: Axial Mode Helical Antenna
3 The Model
The shape of the helical antenna is modeled with FreeCAD[1], the parts of the antenna is exported in STL CAD format. EM can import the STL CAD format so did it.
The computation region is 0.15 x 0.15 x 0.6 and blocked cells are generated with Level4-3 automatically. The blocked cells distribution is shown in Fig.2.
4 The Results
The model is simulated with Electro Magnetica Numerica 1.7.0. It takes 398 second on iMac 21.5inch late 2013 (Intel i5 4 cores).
The computed directivity is shown in Fig. 3.
(a) a (b) b
Figure 2: The generated blocked cells distribution for the Helical Antenna model.
Figure 3: Directivity
5 Summary
2.4GHz BandAxial Mode Helical Antenna is investigaed. An impulse response simulation is performed and simaltaniously Near to Far Field preprocess is performed. The Far Field Pattern is computated using the results. The directivity is well matched the expectation.
References
[1] FreeCAD: An open-source parametric 3D CAD modeler, http://www.freecadweb.org/.
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