Filter block and a signal transceiver comprising such a filter block
A filter block comprising a hybrid filter, the hybrid filter comprising a first signal splitter having a first input port and a first output port; a second signal splitter having a first input port and a first output port; each of the first and second splitters having first and second connection ports; the two first connection ports being connected together by a first signal path comprising a first filter; the second two connection ports being connected together by a second signal path comprising a second filter; the first and second signal paths each further comprising a transformer connected between the filter and one of the first and second signal splitters.
1. A filter block comprising:
a hybrid filter, the hybrid filter comprising:
a first signal splitter having a first input port and a first output port;
a second signal splitter having a first input port and a first output port;
each of the first and second signal splitters having first and second connection ports;
the two first connection ports being connected together by a first signal path comprising a first filter;
the two second connection ports being connected together by a second signal path comprising a second filter;
the first signal path further comprising a transformer connected between the first filter and one of the first connection ports; and
the second signal path further comprising a transformer connected between the second filter and one of the second connection ports;
wherein the turns ratio of each of the transformers is 1:n, wherein n is substantially sqrt(2)+1 or sqrt(2)−1.
2. A filter block as claimed in claim 1 , wherein the first and second signal splitters are 3 dB hybrids.
3. A filter block as claimed in claim 1 , wherein the first and second filters are identical.
4. A filter block as claimed in claim 1 , wherein the first and second filters are different from each other.
5. A filter block as claimed in claim 1 , wherein each of the first and second filters is at least one of a low pass filter, a high pass filter, a band stop filter, or band pass filter.
6. A filter block as claimed in claim 5 , wherein the first and second filters are band pass filters.
7. A filter block as claimed in claim 1 , wherein the two transformers are identical.
8. A filter block as claimed in claim 1 , wherein each transformer is arranged between the first signal splitter and the first filter.
9. A filter block as claimed in claim 1 , wherein each transformer is arranged between the second signal splitter and the second filter.
10. A filter block as claimed in claim 1 , further comprising at least one directional filter connected in cascade with the hybrid filter.
11. A filter block as claimed in claim 10 , further comprising a plurality of directional filters, the plurality of directional filters and the hybrid filter being connected in cascade.
12. A signal transceiver comprising:
a filter block comprising:
a hybrid filter, the hybrid filter comprising:
a first signal splitter having a first input port and a first output port;
a second signal splitter having a first input port and a first output port;
each of the first and second signal splitters having first and second connection ports;
the two first connection ports being connected together by a first signal path comprising a first filter;
the two second connection ports being connected together by a second signal path comprising a second filter;
the first signal path further comprising a transformer connected between the first filter and one of the first connection ports; and
the second signal path further comprising a transformer connected between the second filter and one of the second connection ports;
wherein the turns ratio of each of the transformers is 1:n, wherein n is substantially sqrt(2)+1 or sqrt(2)−1;
an antenna in electrical communication with the input port of the first signal splitter of the hybrid filter;
first and second signal receivers in electrical communication with the output ports of the first and second signal splitters of the hybrid filter respectively; and
a signal transmitter in electrical communication with the output port of the first signal splitter of the hybrid filter.