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

• Frequency range 470-862 MHz, 470-702 MHz together with GSM 900
transmitter.
• Bandwidth 392 MHz (58.9 %), 232 MHz (39.6 %) together with GSM 900
transmitter.
• Channel bandwidth 5, 6, 7 or 8 MHz.
• Minimum power gain –10 dBi at 474 MHz linearly increasing to –5 dBi at
858 MHz.
• 50 Ω impedance matching.
• As omni directional radiation pattern as possible.
• Polarisation problem can be an issue.
• A filter is needed on the DVB-H chipset input to block GSM 900 signal
and a LNA is preferable. This is not an antenna issue but as high isolation
against GSM 900 as possible is wanted.
• Low efficiency will be tolerated due to the electrically small antennas.
• The DVB-H chipset sets the sensitivity level, today’s chipset have a level
of about –95 dBm.
We still have some prototypes to evaluate. The most interesting is to replace the
switches and the matching circuits with a balun and variable capacitance diodes in
the switch monopole 2. This way the antenna could be controlled by an analogue
control voltage and no expensive switches have to be used.
We planned to do isolation measurements of the different prototypes but we did
not have enough time for this. These are important measurements that have to be
done to be able to decide the filter characteristic.
To be able to verify and to get some more reliable measurement results it would
have been interesting to do measurements in a larger chamber suitable for DVB-H
frequencies.
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