Monitoring antenna system

In a monitoring system for detecting the presence of a tag, the improvement comprising:

• a digital signal source for generating digital signals representing selected frequencies;
• an antenna tap connected to said signal source for receiving said digital signals and generating an analog signal having a signal frequency of one of said selected frequencies, said tap including differential antenna drivers;
• and
• a differentially drive planar antenna loop connected to said antenna drivers for transmitting signals at the signal frequency of said analog signal.

In a monitoring system for detecting the presence of a tag, the improvement comprising:

• a digital signal source for generating digital signals representing selected frequencies;
• an antenna tap connected to said signal source for receiving said digital signals and generating an analog signal having a signal frequency of one of said selected frequencies;
• and
• a portal planar loop antenna connected to said antenna tap for transmitting signals at the signal frequency of said analog signal;
• wherein
• said antenna is responsive to the signals from said tap for generating a magnetic field surrounding said loop at said analog signal frequency;
• and
• said portal antenna has a magnetic field coupling to the tag in said magnetic field being transported through said loop.

In a monitoring system for detecting the presence of a tag, the improvement comprising:

• a digital signal source for generating digital signals representing selected frequencies;
• an antenna tap connected to said signal source for receiving said digital signals and generating an analog signal having a signal frequency of one of said selected frequencies;
• and
• a transversal planar loop antenna connected to said antenna tap for transmitting signals at the signal frequency of said analog signal;
• wherein
• said antenna is responsive to signals from said tap for generating a magnetic field surrounding said loop at said analog signal frequency;
• and
• said transversal antenna has a magnetic field coupling to the tag in said magnetic field being transported adjacent said loop.

In a monitoring system for detecting the presence of a tag the improvement comprising:

• a digital signal source for generating digital signals representing selected frequencies;
• a plurality of antenna taps connected to said signal source for receiving said digital signals and generating respective first and second analog signals each having a frequency corresponding to one of said selected frequencies;
• a first planar antenna loop connected to one of said antenna taps for transmitting signals at the signal frequency of the first analog signal;
• and
• a second planar antenna loop connected to another of said antenna taps for transmitting signals at the signal frequency of the second analog signal;
• wherein
• said first and second planar antenna loops are positioned in planes at an angle with respect to each other.

In a monitoring system for detecting the presence of a tag the improvement comprising;

• a digital signal source for generating digital signals representing selected frequencies;
• a plurality of antenna taps connected to said signal source for receiving said digital signals and generating respective first and second analog signals each having a frequency corresponding to one of said selected frequencies;
• a first portal planar antenna loop connected to one of said antenna taps for transmitting signals at the signal frequency of the first analog signal;
• and
• a second portal planar antenna loop connected to another of said antenna taps for transmitting signals at the signal frequency of the second analog signal;
• wherein
• said first and second portal planar antenna loops are positioned in parallel planes spaced along a path of the tag to be detected;
• and
• each of said antenna loops is driven differentially with respect to each other to cancel noise existing along said path.

In a monitoring system for detecting the presence of a tag, the improvement comprising:

• a digital signal source for generating digital signals representing selected frequencies;
• a first antenna tap and a second antenna tap each connected to said signal source for receiving said digital signals and generating analog signals each having a frequency correspondence to one of said selected frequencies;
• and
• a first planar antenna loop connected to said first antenna tap for transmitting signals at the signal frequency of the first analog signal;
• a second planar antenna loop connected to said second antenna tap for transmitting signals at the signal frequency of the second analog signal;
• wherein
• said first and second antenna taps drive said first and second planar antenna loops respectively with respective signals that are phase shifted with respect to each other.

In a monitoring system for detecting the presence of a tag the improvement comprising:

• a digital signal source for generating digital signals representing selected frequencies and for generating transmit mode signals and receive mode signals;
• an antenna tap connected to said signal source for receiving said digital signals and said mode signals and generating an analog signal having a signal frequency of one of said selected frequencies;
• and
• a planar transceiver antenna loop connected to said antenna tap for transmitting signals at the signal frequencies of said analog signal and for receiving signals transmitted by the tag;
• wherein
• said antenna tap is connected to said planar transceiver antenna loop for receiving and amplifying tag signals detected by said antenna.

In a monitoring system for detecting the presence of a tag, the improvement comprising:

• a digital signal source for generating digital signals representing selected frequencies and for generating transmit mode signals and receive mode signals;
• an antenna tap connected to said signal source for receiving said digital signals and mode signals and generating an analog signal having a signal frequency of one of said selected frequencies;
• and
• a planar portal transceiver loop antenna connected to said antenna tap for transmitting signals at the signal frequency of said analog signal and for receiving signals transmitted by the tag;
• wherein
• said portal planar transceiver loop antenna is responsive to signals from said tap for generating a magnetic field surrounding said loop at said analog signal frequency and is responsive to signals received from a tag;
• and
• said antenna tap is connected to said antenna for receiving and amplifying tag signals detected by said antenna.

In a monitoring system for detecting the presence of a tag, the improvement comprising:

• a digital signal source for generating digital signals representing selected frequencies and for generating transmit mode signals and receive mode signals;
• an antenna tap connected to said signal source for receiving said digital signals and said mode signals and generating an analog signal having a signal frequency of one of said selected frequencies;
• and
• a planar transceiver antenna loop connected to said antenna tap for transmitting signals at the signal frequency of said analog signal and for receiving signals transmitted by the tag;
• wherein
• said antenna tap responsive to said mode signals for selecting the reactance of a resonant circuit including said antenna;
• and
• said planar transceiver antenna loop has a higher Q during said transmit mode signal than during said receive mode signal.

In a monitoring system for detecting the presence of a tag, the improvement comprising:

• a digital signal source for generating digital signals representing selected frequencies and for generating transmit mode signals, receive mode, signals, and squelch mode signals;
• an antenna tap connected to said signal source for receiving said digital signals and mode signals and generating an analog signal having a signal frequency of one of said selected frequencies;
• and
• a planar transceiver loop antenna connected to said antenna tap for transmitting signals at the signal frequency of said analog signal and for receiving signals transmitted by the tag;
• wherein
• said antenna tap is responsive to said mode signals for selecting the reactance of a resonant circuit including said antenna and for squelching all transmissions in response to said squelch mode signal;
• and
• said planar transceiver antenna loop has a higher Q during said transmit mode signal than during said receive mode signal and being squelched during said squelch signal.

In a monitoring system for detecting the presence of a tag the improvement comprising:

• a digital signal source for generating digital signals representing selected frequencies;
• an antenna tap connected to said signal source for receiving said digital signals and generating an analog signal having a signal frequency of one of said selected frequencies;
• a planar transceiver antenna loop connected to said antenna tap for transmitting signals at the signal frequency of said analog signal and for receiving signals transmitted by the tag;
• and
• a resonant circuit including said antenna;
• wherein
• said resonant circuit has a higher Q when said antenna is transmitting than when said antenna is receiving.