OMNIRANGE NAVIGATION APPARATUS AND METHOD

• US 3,754,259 A
• Filed: 07/22/1970
• Issued: 08/21/1973
• Est. Priority Date: 07/22/1970
• Status: Expired due to Term

• Current Assignee: Robert W. Redlich
• Original Assignee: Robert W. Redlich
• Inventors: Redlich, Robert W.
• Primary Examiner(s): Borchelt, Benjamin A.
• Assistant Examiner(s): Berger, Richard E.
• Application Number:
  US05/057,097
• Time in Patent Office: 1,126 Days
• Field of Search: 343/16R,16D,102
• US Class Current: 342/404
• CPC Class Codes: G01S 1/02 using radio waves G01S19/00 takes precedence
• CPC Class Codes: H01Q 3/26 varying the relative phase or relative amplitude of energisation between two or more active radiating elements; varying the distribution of energy across a radiating aperture H01Q3/12, H01Q3/22, H01Q3/24 take precedence

Abstract

An amnirange navigation apparatus and method wherein a reference signal is radiated and a ring antenna array radiates a variable phase signal which rotates bodily at a first frequency without physically rotating the array and which has sharp zero crossings. The measured phase between the received reference and variable signals is equal to the bearing between the transmitter and receiver. The receiver uses zero crossing techniques for phase measurement so that possible bearing errors which might be caused by reflected signals are reduced in direct proportion to the slope at the zero crossings.

Claims

1. An omnidirectional navigation apparatus, comprising, in combination:

first means for radiating a reference phase pattern and a variable phase radiation pattern having zero crossings at which the slope is greater than one; and

second means for receiving and measuring the phase or time displacement between predetermined ones of said zero crossings to determine the bearing between said first means and said second means.

2. An omnidirectional navigation apparatus characterized substantially in accordance with claim 1, wherein said first means includes a transmitting antenna array which possesses circular symmetry and which radiates only a horizontally polarized signal.

3. An omnidirectional navigation apparatus characterized substantially in accordance with claim 1, wherein said first means includes a transmitting array of a predetermined number of omnidirectional loop antennas disposed in a circular pattern, and includes modulating means to change the currents in each of said omnidirectional loop antennas so that said variable phase radiation pattern rotates bodily at a first predetermined frequency without physical rotation of said transmitting array.

4. An omnidirectional navigation apparatus characterized substantially in accordance with claim 1, wherein said first means includes two concentric ring antenna arrays, one of said two concentric ring antenna arrays radiates only a first predetermined frequency component of said variable phase radiation pattern, and the other of said two concentric ring antenna arrays radiates the remaining harmonic components in said variable phase radiation pattern.

5. An omnidirectional navigation apparatus characterized substantially in accordance with claim 1, whereinsaid first means includes a transmitting ring antenna array and an omnidirectional antenna structure disposed at the center of said ring array, said omnidirectional antenna structure raidating a first predetermined frequency component of said variable phase radiation pattern, and said ring array radiating the remaining harmonic components in said variable phase radiation pattern.

6. An omnidirectional navigation apparatus characterized substantially in accordance with claim 1, wherein said first means includes at least one transmitting ring antenna array which radiates an approximate square wave having a relatively high slope at said zero crossings and only one zero crossing for each half cycle and wherein the highest order harmonic component is accentuated as much as possible without generating another zero crossing within each said half cycle.

7. An omnidirectional navigation apparatus characterized substantially in accordance with claim 1, wherein said first means includes at least one ring array of antenna elements having a minimum ring circumference in wave lengths which is approximately equal to the order of the highest azimuth harmonic to be radiated, and having a minimum number of said antenna elements required for radiation of harmonic order N which is equal to 2N +1.

8. An omnidirectional navigation apparatus characterized substantially in accordance with claim 1, wherein said first means includes a ring array of loop antenna elements which permit the ring array to radiate an omnidirectional reference signal and a variable phase signal, modulating means to change the currents in each of said loop antenna elements so that said variable phase signal rotates bodily at a first predetermined frequency and to eliminate disturbances of the variable phase signal which might be caused by mutual coupling between said elements of said ring array, and wherein said second means includes an omnirange receiver employing zero crossing techniques for phase detection.

9. An omnirange navigation method comprising the steps of:

generating an omnidirectional reference signal and a horizontally polarized variable phase polar signal having zero crossings at which the slope is greater than 1 and with only one zero crossing for each half cycle;

radiating said signals from at least one ring antenna array disposed at a first predetermined location without physically rotating said ring antenna array;

receiviNg said signals at a second location; and

measuring the phase difference between the received signals to determine the bearing between said first predetermined location and said second location.

10. An omnirange navigation method characterized substantially in accordance with claim 9, including the steps of modulating the currents in each antenna element comprising said ring antenna array so that said radiated variable phase signal rotates bodily at a first predetermined frequency, cancelling out the carrier component of the current output of said signals to leave only modulation sidebands, and employing zero crossing techniques for phase measurement of said received signals.

11. An omnidirectional navigation apparatus characterized substantially in accordance with claim 1, wherein:

said first means includes modulating means and a plurality of antennas;

said modulating means includes a common voltage source, a plurality of lambda /2 lines, a plurality of lambda lines, a variable radius rotatable drum, a predetermined number of elements which are lambda /4 in length surrounding said drum, and circuit means for connecting said modulating means to each of said antennas;

each of said elements and the surface of said drum forms a lambda /4 line whose characteristic impedance varies with time;

the input end of half of said lambda /4 lines is connected to said common voltage source through said lambda /2 lines;

the input end of the remaining half of said lambda /4 lines is connected to said common voltage source through said lambda lines; and

the output end of said lambda /4 lines form variable current sources whoch are connected through said circuit means to said antennas in diametrically opposite pairs to cancel out the carrier component of current output leaving only modulation side-bands, so that said modulating means effectively drives each of said antennas with an associated one of said current sources whose magnitude varies in time in a manner appropriate to radiate said variable phase radiation pattern with a pattern rotation at a first predetermined frequency.