Design of Antennas for Handheld DVB-H ... - Lunds tekniska högskola
Design of Antennas for Handheld DVB-H ... - Lunds tekniska högskola
Design of Antennas for Handheld DVB-H ... - Lunds tekniska högskola
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Figure 4.31. Return loss graph <strong>for</strong> matching circuit 4 <strong>for</strong> switched monopole 2.<br />
The result from the return loss graphs <strong>for</strong> the different switched monopole<br />
antennas is satisfactory. There are some differences <strong>for</strong> example the varying level<br />
<strong>of</strong> the return loss graphs <strong>for</strong> the different prototypes, which depends on the loss in<br />
the switches. It is only the anechoic chamber measurement that can show how<br />
much the switches affect the per<strong>for</strong>mance <strong>of</strong> the antenna and show if the prototype<br />
is good enough even though there are losses in the switches.<br />
A switched dipole has also been tested, with the same design as the switched<br />
monopole but with an extra antenna element along the other side <strong>of</strong> the ground<br />
plane connected to the ground plane. The test result showed that the switched<br />
dipole has somewhat better per<strong>for</strong>mance than the switched monopole. But the<br />
conclusion <strong>of</strong> the test is that the antenna element connected to the ground just<br />
enlarges the ground plane and the small increase <strong>of</strong> per<strong>for</strong>mance does not<br />
motivate the increase <strong>of</strong> cost and size it will mean.<br />
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