Design of Antennas for Handheld DVB-H ... - Lunds tekniska högskola

antenna. The dimension of the antenna element was chosen so it fits in a normal
handheld device. If it had been possible with a wider antenna element it had
maybe been enough with two or three matching networks instead. The distance
between the antenna element and the ground plane is an important parameter for
the antenna characteristic, the longer the distance the better the performance, both
deeper and wider return loss graph. All switched monopole prototypes have been
built with a distance between ground plane and the antenna element of 3 mm.
After designing the four different matching circuits, as shown in the schematic in
figure 4.21 with component values according to table 4.1, the return loss was
measured. The result of the return loss measurement is presented in figure 4.22.
Figure 4.21. Schematic for four matching circuits for the switched monopole
concept.
Table 4.1. Value of components for the three different switched monopole
prototypes.
Circuit 1 Circuit 2 Circuit 3 Circuit 4
without RF
switches
Switched
monopole 1
Switched
monopole 2
C1
L1
C2
/pF /nH /pF /nH /pF /nH /pF /nH
12 19.5 10 15 8 11.2 7 7.5
45
L2
12 12 10 10 7 8.2 6 4.7
10 15 10 8.2 7 3.9 6 0
C3
L3
C4
L4