bandwidth, the capability to achieve the performance is obvious.
We made a comparison of the results obtained with the structure maintained by the U shape without any soldering and the one obtained with soldering without support. Except in the upper frequency band, there is no different between the results, showing again that this concept is not especially sensitive to the supporting structure provided that the material is chosen adequately.
In Figure 5, we present the radiation pattern of such a disk at 2.4 GHz. This disk shows the same behavior as the w x classical monopole disk described in 4 . However, it presents many ripples because the dimensions of the supporting substrate which were only 8 cm = 10 cm.
In Figure 6, we present the matching performances of a double ellipse of ratio 0.5, the major axis of which is 10 mm. The structure is set on the same line as that described previously, and should be matched to 8 GHz. Figure 6 shows a matching better than 7 dB over the 1.5 GHz band. Again, it is possible by sliding the monopole to optimize the matching according to the frequency band desired.
This structure could be used in higher frequency ranges with only the following limitations taken into account:
β
· the manufacturing of the radiating structure, β
· the coupling effect in between the matching line and the radiating structure.
However, up to 20 GHz, the structure has dimensions which are acceptable for the purposes of incorporating it into a complete system.
CONCLUSION
The realization of a new surface-mounted antenna type has been shown. A comparison between a conventional structure and this new way of attaching the monopole shows the consistency of the approach. The major advantages and limitations of the concept were described; it is shown that this approach avoids the use of a connector through the ground plane, and that it is mainly suitable for broadband monopole application. We were able to achieve 7 dB of matching through a 3 GHz bandwidth. The only limitations were shown to be the manufacturing limitations if one intends to use it for a frequency higher than 20 GHz.