LEON-G100 / LEON-G200 - System Integration Manual
GSM.G1-HW-09002-G3
Preliminary
Design-In
Page 95 of 125
2.4.2
Antenna radiation
An indication of the radiated power by the antenna can be approximated by measuring the |S
2\
| from a target
antenna to the measurement antenna, measured with a network analyzer using a wideband antenna.
Measurements should be done at a fixed distance and orientation. Compare the results to measurements
performed on a known good antenna. Figure 53 through Figure 54 show measurement results. A wideband log
periodic-like antenna was used, and the comparison was done with a half lambda dipole tune on 900 MHz
frequency. The measurements show both the |S
11
| and |S
21
| for penta-band internal antenna and for the
wideband antenna.
Figure 53: |S
11
| and |S
21
| comparison of a 900 MHz tuned half wavelength dipole and a penta-band internal antenna
The half lambda dipole tuned to 900 MHz is known to have good radiation performance (both for gain and
directivity). By comparing the |S
21
| measurement with the antenna under investigation for the frequency for
which the half dipole is tuned (e.g. marker 3 in Figure 53) it is possible to rate the antenna being tested. If the
performance of the two antennas is similar then the target antenna is good.
Figure 54: |S
11
| and |S
21
| comparison between a 900 MHz tuned half wavelength dipole and a wideband commercial antenna
If |S
21
| values for the tuned dipole are much better than for the antenna under evaluation (e.g. as seen by
markers 1 and 2 of the S21 comparison in Figure 54, where the dipole performance is 5 dB better), then it can
be concluded that the radiation of the antenna under evaluation is considerably less.
The same procedure should be repeated for other bands with the half wavelength dipole re-tuned to the band
under investigation.
