| 摘要 |
<p>The invention concerns a combination of a transmitter/receiver (12, 13) having a predetermined frequency/wavelength and an antenna (15), the antenna comprising a coiled wire portion (16) one end of which is connected to the output (14) of the transmitter/receiver and a straight wire portion (17) one end of which is connected in series to the other end of the coiled wire portion, the combined length of the portions being no more than one quarter wavelength, the inductive reactance of the coiled wire portion (16) being selected to both substantially tune out the capacitive reactance of the transmitter (12, 13) and the capacitive reactance of the straight wire portion so that the overall impedance of the system is predominantly resistive, and at least the majority of the coiled portion (16) being external to the conductive portion (12) of the transmitter so as to effectively add to the electrical length of at least the straight portion (17) and itself act as a radiator. The system is particularly designed to be used with no ground plane or only a partial ground plane and with the antenna length less than quarter wavelength. This is particularly useful in the sport of falconry. The system of the invention gives a higher output than a conventional quarter wavelength straight antenna with no ground plane.</p> |
