Gerald provides a very interesting discussion of antennas in the FlexInsider Issue 2; but, what is wrong with just paralleling antennas for different bands together?
Lets suppose that we wish to monitor both 20 meters and 80 meters at the same time. If we have two antennas that are resonant respectively on 20 and 80 meters and we parallel them together, the receiving SCU's should be happy. Yes, even though there is a high impedance for the out-of-resonant antenna, the receive losses will be low and we will get signals from both antennas. But, nothing bad should happen. At transmit time, if I transmit to the paralled antennas on 20 meters, the transmitter will see a high impedance on the 80 meter antenna and llittle energy will go out on that antenna. The 20 meter antenna being resonant, will accept the transmitted energy. The reverse holds true if I transmit on 80 meters. This is the same principle that makes the multi-band "fan dipole" work, where a single feedline feeds multiple resonant dipoles. Perhaps decoupling stubs might be needed for each antenna in this case. Am I all wet? Perhaps someone with a better knowledge of transmission lines and antennas can challenge and clarify this. George K2CM . _______________________________________________ Flexedge mailing list [email protected] http://mail.flex-radio.biz/mailman/listinfo/flexedge_flex-radio.biz This is the FlexRadio Systems e-mail Reflector called FlexEdge. It is used for posting topics related to SDR software development and experimentalist who are using beta versions of the software.
