Multi-band antennas having enhanced directors therein that inhibit radiation interference across multiple frequency bands
An antenna includes a first radiating element configured to emit first electromagnetic radiation in response to at least one feed signal having a frequency within a first radio frequency (RF) band. A director is provided, which is positioned forwardly of the first radiating element, and in a path of the first electromagnetic radiation. The director includes first and second passive impedance elements that provide respective first and second frequency-dependent reactances to first currents induced within the director in response to the first electromagnetic radiation. The first and second passive impedance elements may include a first inductor and a first capacitor, which are electrically coupled in series. The director may also be configured to include a plurality of passive impedance elements that are connected within an impedance loop containing a second LC circuit in series with a first LC circuit.
1. An antenna, comprising:
a first radiating element configured to emit first electromagnetic radiation in response to at least one feed signal having a frequency within a first radio frequency (RF) band; and
a director positioned forwardly of the first radiating element, and in a path of the first electromagnetic radiation, said director comprising a plurality of passive impedance elements that provide frequency-dependent reactances to first currents induced within the director in response to the first electromagnetic radiation, said plurality of passive impedance elements including a first series LC circuit and a second series LC circuit, which are electrically coupled in series within an impedance loop that supports the first currents therein.
2. The antenna of claim 1 , wherein the plurality of passive impedance elements include a third LC circuit in series with the first and second LC circuits.
3. The antenna of claim 1 , wherein the director is positioned adjacent a path of second electromagnetic radiation emitted by a second radiating element; and wherein the director is configured to provide a greater frequency-dependent impedance to second currents induced within the director in response to the second electromagnetic radiation relative to the first currents.
4. The antenna of claim 3 , further comprising:
a reflector;
a first array of radiating elements extending in a lengthwise direction along a first side of the reflector;
a second array of radiating elements extending in a lengthwise direction along a second side of the reflector; and
a third array radiating elements extending in a lengthwise direction across the reflector, and between the first and second arrays of radiating elements; and
wherein the radiating elements in the first and second arrays are configured as the first radiating element;
wherein the radiating elements in the third array are configured as the second radiating element; and
wherein the director is within an array of directors extending forwardly of the radiating elements within the first array.
5. The antenna of claim 1 , wherein a distance between the director and a forward-facing surface of the first radiating element is in a range from λ/8 to 3λ/8, where λ is equivalent to a wavelength of a center frequency within the first RF band.
6. The antenna of claim 5 , wherein the director extends parallel to radiating arms within the first radiating element.
7. The antenna of claim 1 , wherein a geometric shape of the capacitor in the first LC circuit is equivalent to a geometric shape of the capacitor in the second LC circuit.
8. The antenna of claim 1 , wherein a geometric shape of the inductor in the first LC circuit is equivalent to a geometric shape of the inductor in the second LC circuit.
9. The antenna of claim 1 , wherein a geometric shape of the capacitor in the first LC circuit is selected from a group consisting of four-sided polygons, triangles, circles, and circular sectors.