Apparatus and method for broadband matching of electrically small antennas

A broadband impedance matching circuit for interfacing an antenna to one of a signal source and a load, the matching circuit comprising:

• a negative capacitor circuit;
• a negative inductor circuit, the negative capacitor circuit and negative inductor circuit being connected as a resonant circuit having a first and second terminal, the first terminal being electrically connected to the antenna;
• and
• a dynamic dispersive impedance transformer circuit, the dynamic dispersive impedance transformer circuit comprising:
• a first reactance circuit, the first reactance circuit having a first terminal, a second terminal and a reactance associated therebetween, the first terminal being connected to the second terminal of the resonant circuit;
• and
• a second reactance circuit, the second reactance circuit having a first terminal, a second terminal and a reactance associated therebetween, the reactance of the second reactance circuit being selected to be equal and opposite to the reactance of the first reactance circuit, the first terminal of the second reactance circuit being connected to the second terminal of the first reactance circuit and serving as an output terminal for the dynamic dispersive impedance transformer circuit for connection to one of the signal source and the load, the second terminal of the second reactance circuit being electrically coupled to circuit ground, the dynamic dispersive impedance transformer circuit receiving a first signal having a frequency dependent radiation resistance component from the antenna and transforming the first signal into a second signal having a substantially constant real resistance, the dynamic dispersive impedance transformer circuit providing the second signal at the output terminal.

A method of broadband impedance matching an antenna with one of a signal source and a load, the antenna exhibiting a frequency dependent Foster reactance and a frequency dependent radiation resistance, which comprises the steps of:

• neutralizing the Foster reactance of the electrically small antenna by operatively coupling thereto a circuit exhibiting a non-Foster reactance;
• transforming effectively the frequency dependent radiation resistance of the antenna into a substantially frequency independent resistance by operatively coupling a dynamic dispersive impedance transformer circuit to the circuit exhibiting a non-Foster reactance;
• and
• operatively coupling the dynamic dispersive impedance transformer circuit to one of the signal source and the load.