Reflector-backed RFID slot antenna with a cosecant-squared-like radiation pattern

1. An antenna apparatus, comprising:

a slot antenna configured within a ground plane;

a radio frequency signal feed coupled to the slot antenna proximal to one end of the slot antenna; and

a conductive reflector backing the slot antenna and configured to reflect radio frequency energy;

wherein the slot antenna, ground plane, and the reflector are rectangular and cooperatively form a reflector-backed slot antenna and a waveguide formed between the plates of the ground plane and reflector that uses the presence of the reflector to change a total radiated pattern of the apparatus by launching additional peripheral signals around a periphery of the apparatus to provide an antenna radiation pattern of an inverse, mirrored, cosecant-squared radiation pattern.

2. The antenna apparatus of claim 1 , wherein the ground plane is configured with external dimensions of at least one wavelength of a resonant frequency of the slot antenna.

3. The antenna apparatus of claim 1 , wherein the ground plane is configured with external dimensions of one and half wavelengths of a resonant frequency of the slot antenna.

4. The antenna apparatus of claim 1 , wherein the reflector is configured with external dimensions the same as the ground plane.

5. The antenna apparatus of claim 1 , wherein the reflector is parallel to the ground plane and is spaced one-twelfth wavelength from the ground plane.

6. The antenna apparatus of claim 1 , further comprising:

a Radio Frequency Identification (RFID) reader communicatively coupled to the antenna apparatus within a housing, wherein the housing is ceiling-mounted in an RFID read environment, and wherein the ground plane of the antenna apparatus is parallel to the floor of the environment.

7. A Radio Frequency Identification (RFID) reader, comprising:

a housing;

an RFID reader disposed within the housing; and

an antenna apparatus disposed within the housing and communicatively coupled to the RFID reader, wherein the antenna apparatus comprises:

a slot antenna configured within a ground plane;

a radio frequency signal feed coupled between the RFID reader and the slot antenna proximal to one end of the slot antenna; and

a conductive reflector backing the slot antenna and configured to reflect RF energy;

wherein the slot antenna, ground plane, and the reflector are rectangular and cooperatively form a reflector-backed slot antenna and a waveguide formed between the plates of the ground plane and reflector that uses the presence of the reflector to change a total radiated pattern of the apparatus by launching additional peripheral signals around a periphery of the apparatus to provide an antenna radiation pattern to provide an antenna radiation pattern of an inverse, mirrored, cosecant-squared radiation pattern.

8. A method for providing an antenna radiation pattern, the method comprising the steps of:

transmitting radio frequency energy by a rectangular slot antenna configured within a rectangular ground plane and a radio frequency signal feed coupled to the slot antenna proximal to one end of the slot antenna;

reflecting with a rectangular reflector the radio frequency energy transmitted by the slot antenna; and

cooperatively combining the reflected radio frequency energy with the transmitted radio frequency energy via the slot antenna and via a waveguide formed between the ground plane and reflector that uses the presence of the reflector to change a total radiated pattern by launching additional peripheral signals around a periphery of the ground plane and reflector to provide an antenna radiation pattern of an inverse, mirrored, cosecant-squared radiation pattern.

9. The method of claim 8 , further comprising providing a ground plane having a configuration with external dimensions of at least one wavelength of a resonant frequency of the slot antenna.

10. The method of claim 8 , further comprising providing a ground plane having a configuration with external dimensions of one and half wavelengths of a resonant frequency of the slot antenna.

11. The method of claim 8 , further comprising providing a reflector having a configuration with external dimensions the same as the ground plane.

12. The method of claim 8 , further comprising providing a reflector parallel to the ground plane and is spaced one-twelfth wavelength from the ground plane.

13. The method of claim 8 , further comprising providing a Radio Frequency Identification (RFID) reader communicatively coupled to an antenna apparatus within a housing, wherein the housing is ceiling-mounted in an RFID read environment, and wherein the ground plane of the antenna apparatus is parallel to the floor of the environment.