Printed circuit board based smart antenna
Systems and methods are disclosed to transmit and receive radio frequency (RF) signals by providing a plurality of high gain, highly directional antennas on a multi-layer printed circuit board; using a processor to gate RF signals from each antenna and to select an antenna transmission pattern based on antenna turned on or the combination of a number of antennas turned on, among others.
1. An electronic circuit, comprising:
a multi-layer substrate;
a plurality of antennas formed on a first surface of the substrate;
a plurality of switches, each coupled to one antenna in the antenna array;
a processor coupled to the switches to control the plurality of antennas and to optimize radio frequency characteristics of the plurality of antennas;
a radio frequency (RF) circuit; and
a ground circuit border surrounding the RF circuit except for narrow openings for passing signal paths.
2. The circuit of claim 1 , wherein the substrate includes a radio frequency circuit and a processor integrated circuit.
3. The circuit of claim 1 , wherein the antenna includes at least one director and a reflector.
4. The circuit of claim 3 , comprising a ground plane on a second surface of the substrate.
5. The circuit of claim 4 , comprising a matching network coupled to the switches.
6. The circuit of claim 1 , wherein the substrate comprises one of: a semi-insulating compound semiconductor substrate, a micro-strip on printed circuit board, a copper-clad epoxy fiberglass, a Low Temperature Co-fired Ceramic (LTCC) substrate, a gallium arsenide substrate, a silicon substrate.
7. The circuit of claim 1 , wherein the processor selects one or more antennas by scanning the received signal strength for individual antennas and the combination of antennas.
8. The circuit of claim 6 , wherein the switches comprise one or more PIN diodes.
9. The circuit of claim 1 , wherein the antennas comprise PCB Yagi antennas.
10. The circuit of claim 1 , wherein the switches comprise at least one of a MESFET device, a HEMT device.
11. The circuit of claim 1 , wherein one end of the switches is coupled to a receiver comprising a low noise amplifier, a down-converter, a demodulator and an automatic gain control (AGC) amplifier having a gain control voltage signal coupled to the processor.
12. The circuit of claim 1 , comprising software to select an antenna transmission pattern based on a number of antennas turned on.