초록 ▼

A circuit (4) for establishing a desired impedance value for a radio antenna (5) comprising a transistor (3) having an input (8) and an output terminal (6), and a printed radio frequency transformer comprising a first (1) and a second inductor (2), both inductors (1, 2) having a coupling factor valu

A circuit (4) for establishing a desired impedance value for a radio antenna (5) comprising a transistor (3) having an input (8) and an output terminal (6), and a printed radio frequency transformer comprising a first (1) and a second inductor (2), both inductors (1, 2) having a coupling factor value, and having a first and a second terminal (11, 12; 21, 22). The first terminal (11) of the first inductor (1) is adapted for connecting a radio antenna (5). The input terminal (8) of the transistor (3) is connected to the second terminal (12) of the first inductor (1), and the output terminal (6) of the transistor (3) is connected to the first terminal (21) of the second inductor (2), so that the desired impedance value (Z2) at the second terminal (22) of the second inductor (2) is determined by the inductance value of the second inductor (2).

대표청구항 ▼

1. A circuit for establishing a desired impedance value for a radio antenna, comprising: a bipolar junction transistor (BJT) having an emitter, a base, and a collector an, anda printed radio frequency transformer comprising a first and a second printed inductors, both inductors having a coupling fac

1. A circuit for establishing a desired impedance value for a radio antenna, comprising: a bipolar junction transistor (BJT) having an emitter, a base, and a collector an, anda printed radio frequency transformer comprising a first and a second printed inductors, both inductors having a coupling factor value,each one of the inductors (1, 2) having a first and a second terminal, the first terminal of the first inductor being adapted for connecting a radio antenna for receiving an input signal, and the second terminal of the second inductor being adapted for providing an output signal,where the emitter of the transistor is connected to the second terminal of the first inductor, the base is grounded, and the collector is connected to the first terminal of the second inductor, andwhere the impedance value at the first terminal of the first inductor is determined by the coupling factor value, and the desired impedance value at the second terminal of the second inductor is determined by the inductance value of the second inductor. 2. The circuit for establishing a desired impedance value for a radio antenna, according to claim 1, further comprising an RC network connected in parallel with the second inductor to establish a frequency of operation and an output impedance value for the circuit. 3. The circuit for establishing a desired impedance value for a radio antenna, according to claim 2, where the RC network comprises a capacitor suitable for establishing a desired frequency of operation for the circuit. 4. The circuit for establishing a desired impedance value for a radio antenna, according to any of claims 2-3, where the RC network comprises a variable resistor suitable for selecting the impedance value at the second terminal of the second inductor. 5. The circuit for establishing a desired impedance value for a radio antenna, according to any of the preceding claims, where the second inductor is concentrically wound around a central point. 6. The circuit for establishing a desired impedance value for a radio antenna, according to claim 5, where the first inductor at least partially surrounds the second inductor. 7. The circuit for establishing a desired impedance value for a radio antenna, according to any of the preceding claims, where the printed radio frequency transformer is enclosed in a ground frame to isolate radiation from the inductors. 8. The circuit for establishing a desired impedance value for a radio antenna, according to any of the preceding claims, where the first inductor has an inductance value ranging from 10 nH to 20 nH. 9. The circuit for establishing a desired impedance value for a radio antenna, according to any of the preceding claims, where the coupling between inductors is established by the distance between said inductors. 10. An antenna system for a vehicle, comprising: a miniaturized radio antenna,a circuit according to any of the preceding claims, where the first terminal of the first inductor of the circuit is connected to the radio antenna for establishing an output desired impedance value, anda cover for enclosing the miniaturized radio antenna and the circuit;where the antenna system is adapted to be attached to the vehicle. 11. The antenna system for a vehicle, according to claim 10, further comprising at least one of an AM/FM antenna, a digital audio broadcasting (DAB) antenna, a MIMO antenna, a satellite digital audio radio services (SDARS) antenna and a global navigation satellite system (GNSS) antenna. 12. The antenna system for a vehicle, according to claim 11, where the DAB antenna is configured as a spiral antenna having a horizontal near field pattern.