Receiver and method for use with a four-arm spiral antenna

Claim 1

A receiver for locating a source of RF radiation received by a four-arm spiral antenna having an angular measurement frame normal to the antenna axis, comprising detection means for detecting signals received from each of the spiral arms in response to receipt of RF radiation by the antenna; first comparison means for comparing signals detected from a first opposite pair of said spiral arms to produce a first signal that is proportional to a first function of the frequency of the received RF radiation and the angular displacement of the radiation source in the measurement frame; second comparison means for comparing signals detected from the remaining opposite pair of said spiral arms to produce a second signal that is proportional to a second function of the frequency of the received RF radiation and the angular displacement of the radiation source in the measurement frame; and processing means for processing the first and second signals to produce third and fourth signals that are proportional to said angular displacement and independent of the frequency of the received RF radiation; wherein the first comparison means comprises means for comparing the logarithms of the amplitudes of said signals detected from the first opposite pair of spiral arms to produce a said first signal that is proportional to sin (φ T +φ A ), wherein φ T is the angle of said displacement of the radiation source and φ A is an angle that is a function of the frequency of the received RF radiation; wherein the second comparison means comprises means for comparing the logarithms of the amplitudes of said signals detected from the remaining opposite pair of spiral arms to produce a said second signal that is proportional to cos (φ T +φ A ); and wherein the processing means comprises a first multiplier for multiplying the first signal by cos φ A to produce a fifth signal; a second multiplier for multiplying the first signal by sin φ A to produce a sixth signal; a third multiplier for multiplying the second signal by -sin φ A to produce a seventh signal; a fourth multiplier for multiplying the second signal by cos φ A to produce an eighth signal; a first summing means for adding the fifth and seventh signals to produce the third signal, wherein the third signal is proportional to sin φ T ; and a second summing means for adding the sixth and eighth signals to produce the fourth signal, wherein the fourth signal is proportional to cos φ T .

Claim 5

A method for locating a source of RF radiation received by a four-arm spiral antenna having an angular measurement frame normal to the antenna axis, comprising the steps of: (a) detecting signals received from each of the spiral arms in response to receipt of RF radiation by the antenna; (b) comparing signals detected from a first opposite pair of said spiral arms to produce a first signal that is proportional to a function of the frequency of the received RF radiation and the angular displacement of the radiation source in the measurement frame; (c) comparing signals detected from the remaining opposite pair of said spiral arms to produce a second signal that is proportional to a second function of the frequency of the received RF radiation and the angular displacement of the radiation source in the measurement frame; and (d) processing the first and second signals to produce third and fourth signals that are proportional to said angular displacement and independent of the frequency of the radiation source; wherein step (b) comprises comparing the logarithms of the amplitudes of said signals detected from the first opposite pair of spiral arms to produce a said first signal that is proportional to sin (φ T +φ A ), wherein φ T is the angle of said displacement of the radiation source and φ A is an angle that is a function of the frequency of the received RF radiation; wherein step (c) comprises comparing the logarithms of the amplitudes of said signals detected from the remaining opposite pair of spiral arms to produce a said second signal that is proportional to cos (φ T +φ A ); and wherein step (d) comprises the steps of: (e) multiplying the first signal by cos φ A to produce a fifth signal; (f) multiplying the first signal by sin φ A to produce a sixth signal; (g) multiplying the second signal by -sin φ A to produce a seventh signal; (h) multiplying the second signal by cos φ A to produce an eighth signal; (i) adding the fifth and seventh signals to produce the third signal, wherein the third signal is proportional to sin φ T ; and (j) adding the sixth and eighth signals to produce the fourth signal, wherein the fourth signal is proportional to cos φ T .

Claim 6

A method for locating a source of RF radiation received by a four-arm spiral antenna having an angular measurement frame normal to the antenna axis, comprising the steps of: (a) detecting signals received from each of the spiral arms in response to receipt of RF radiation by the antenna; (b) comparing signals detected from a first opposite pair of said spiral arms to produce a first signal that is proportional to a function of the frequency of the received RF radiation and the angular displacement of the radiation source in the measurement frame; (c) comparing signals detected from the remaining opposite pair of said spiral arms to produce a second signal that is proportional to a second function of the frequency of the received RF radiation and the angular displacement of the radiation source in the measurement frame; and (d) processing the first and second signals to produce third and fourth signals that are proportional to said angular displacement and independent of the frequency of the radiation source; wherein step (b) comprises comparing the logarithms of the amplitudes of said signals detected from the first opposite pair of spiral arms to produce a said first signal that is proportional to sin (φ T +φ A ), wherein φ T is the angle of said displacement of the radiation source and φ A is an angle that is a function of the frequency of the received RF radiation; wherein step (c) comprises comparing the logarithms of the amplitudes of said signals detected from the remaining opposite pair of spiral arms to produce a said second signal that is proportional to cos (φ T +φ A ); and wherein step (d) comprises the steps of: (e) multiplying the first signal by cos φ A to produce a fifth signal; (f) multiplying the first signal by sin φ A to produce a sixth signal; (g) multiplying the second signal by -sin φ A to produce a seventh signal; (h) multiplying the second signal by cos φ A to produce an eighth signal; (i) adding the fifth and seventh signals to produce the third signal, wherein the third signal is proportional to sin φ T ; and (j) adding the sixth and eighth signals to produce the fourth signal, wherein the fourth signal is proportional to cos φ T .

Claim 7

A method for locating a source of RF radiation received by a four-arm spiral antenna having an angular measurement frame normal to the antenna axis, comprising the steps of: (a) detecting signals received from each of the spiral arms in response to receipt of RF radiation by the antenna; (b) comparing signals detected from a first opposite pair of said spiral arms to produce a first signal that is proportional to a function of the frequency of the received RF radiation and the angular displacement of the radiation source in the measurement frame; (c) comparing signals detected from the remaining opposite pair of said spiral arms to produce a second signal that is proportional to a second function of the frequency of the received RF radiation and the angular displacement of the radiation source in the measurement frame; and (d) processing the first and second signals to produce third and fourth signals that are proportional to said angular displacement and independent of the frequency of the radiation source; wherein step (b) comprises comparing the phases of said signals detected from the first opposite pair of spiral arms to produce a said first signal that is proportional to cos (φ T +φ A ), wherein φ T is the angle of said displacement of the radiation source and φ A is an angle that is a function of the frequency of the received RF radiation; wherein step (8c) comprises comparing the phases of said signals detected from the remaining opposite pair of spiral arms to produce a said second signal that is proportional to sin (φ T +φ A ); and wherein step (d) comprises the steps of (e) multiplying the first signal by cos φ A to produce a fifth signal; (f) multiplying the first signal by -sin φ A to produce a sixth signal; (g) multiplying the second signal by sin φ A to produce a seventh signal; (h) multiplying the second signal by cos φ A to produce an eighth signal; (i) adding the fifth and seventh signals to produce the third signal, wherein the third signal is proportional to cos φ T ; and (j) adding the sixth and eighth signals to produce the fourth signal, wherein the fourth signal is proportional to sin φ T .

Claim 8

A method for locating a source of RF radiation received by a four-arm spiral antenna having an angular measurement frame normal to the antenna axis, comprising the steps of: (a) detecting signals received from each of the spiral arms in response to receipt of RF radiation by the antenna; (b) comparing signals detected from a first opposite pair of said spiral arms to produce a first signal that is proportional to a function of the frequency of the received RF radiation and the angular displacement of the radiation source in the measurement frame; (c) comparing signals detected from the remaining opposite pair of said spiral arms to produce a second signal that is proportional to a second function of the frequency of the received RF radiation and the angular displacement of the radiation source in the measurement frame; and (d) processing the first and second signals to produce third and fourth signals that are proportional to said angular displacement and independent of the frequency of the radiation source; wherein step (b) comprises comparing the phases of said signals detected from the first opposite pair of spiral arms to produce a said first signal that is proportional to cos (φ T +φ A ), wherein φ T is the angle of said displacement of the radiation source and φ A is an angle that is a function of the frequency of the received RF radiation; wherein step (8c) comprises comparing the phases of said signals detected from the remaining opposite pair of spiral arms to produce a said second signal that is proportional to sin (φ T +φ A ); and wherein step (d) comprises the steps of (e) multiplying the first signal by cos φ A to produce a fifth signal; (f) multiplying the first signal by -sin φ A to produce a sixth signal; (g) multiplying the second signal by sin φ A to produce a seventh signal; (h) multiplying the second signal by cos φ A to produce an eighth signal; (i) adding the fifth and seventh signals to produce the third signal, wherein the third signal is proportional to cos φ T ; and (j) adding the sixth and eighth signals to produce the fourth signal, wherein the fourth signal is proportional to sin φ T .