# Target Location Using Dual-Beam Directional Modulated Circular Array

Abstract: A new concept directed toward the location of an object within a sector of space is introduced, by using a combination of the properties associated with directional modulation when implemented on a circular antenna array. In particular, we show that a circular antenna array can be made to project orthogonal data streams on orthogonal spatial beams and, through this process, create a temporal and spatial interference pattern that can be used for target location. This is demonstrated by the way of simulation of a two-beam 16-element circular antenna array carrying quadrature phase shift keying data.

## Summary (2 min read)

### Introduction

- In particular, the authors show that a circular antenna array can be made to project orthogonal data streams on orthogonal spatial beams and through this process create a temporal and spatial interference pattern that can be used for target location.
- I. INTRODUCTION Directional Modulation (DM), is a transmitter technology that is capable of projecting digitally modulated information signals into prespecified spatial directions while simultaneously distorting the constellation formats of the same signals in all other directions, [1].
- This approach adds additional flexibility as well as grossly simplifying the practical arrangements in [2] for achieving the same result.
- Section II describes the main properties of the circular array and the dual beam DM approach that are relevant to this paper.
- Two cases are examined (i) symmetrical beam overlay and (ii) asymmetrical beam overlay.

### A. General Circular Array Principle

- Consider a multimode circular array consisting of 16 halfwavelength dipole antennas.
- Manuscript received February 5, 2018, revised XXX, published XXX .
- For any other purposes, permission must be obtained from the IEEE by emailing pubs-permissions@ieee.org.
- (7) From which the QPSK symbol transmitted can be decoded at the receiver along an azimuthal direction ϕ.

### III. SINGLE CYLINDER CIRCULAR ARRAY

- In all other cases where FΣ(ϕ) ≠ FΔ(ϕ), consecutive symbols’.
- Since any QPSK symbol is equally-likely the authors can predict the probability of bit error along ϕ by: Copyright (c) 2018 IEEE.
- On the other hand, when this difference is not calibrated, it will eventually result in a high BER at ϕ = ˗18° and low BER point the azimuth direction ϕ = +18°, reducing two BER minima to one BER minima along the azimuthal angle (see Fig. 5(b)).

### IV. EXPERIMENTAL RESULTS

- To demonstrate the practical implementation of the proposed scheme, multimode circular array (MMCA) is fabricated and far field Copyright (c) 2018 IEEE.
- For any other purposes, permission must be obtained from the IEEE by emailing pubs-permissions@ieee.org.
- The dipoles are uniformly deployed and the separation angle between the consecutive dipoles is 22.5°.
- These measured patterns are post processed to estimate the BER performance along the azimuthal direction.
- In order to evaluate the impact of phase noise on the far field directivity, a simulation campaign was carried out based on the measured phase noise data.

### V. TRACKING APPLICATION

- If the transmitter and the receiver are co-located, then the values required for evaluation of (1) are available.
- Expected received power is deducible from the transmitted FΣ(ϕ) and FΔ(ϕ) in Fig. 3(a), and can be used to evaluate constellation (Fig. 4) at an expected azimuthal direction ϕ.
- This allows the possibility to track the location of the target as it moves in azimuth around the system permitting 360° coverage.
- Here the difference pattern null is shifted to –12° the result of which is to significantly unbalance the DM in the –ϕ° direction while preserving the +ϕ° direction.
- Following this, the sum pattern could be switched off, and the difference pattern null steered onto the target as this would yield better positional estimation since from Fig. 3 the difference pattern beam width at ˗20dB is < 5° while the asymmetrical BER BW is 11.5° for 10-3 BER.

### VI. CONCLUSION

- In this paper the authors show a new concept which relies on the concurrent multiple beam and beam rotation properties of a circular array coupled with the dual directional modulation coding scheme.
- In this way the feasibility of tracking a non-cooperative target has been established.
- The additional possibility of communicating with a suitable receiver equipped target was also described.

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##### Citations

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### Cites background from "Target Location Using Dual-Beam Dir..."

...When β = 2π/λ, λ is the wavelength of operation, and r is the radius of the array [4, 5], αJ is a general representation of element angular location in a circular array with N equally spaced elements at αJ = J2π/N, when J = 1,2, ....

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1 citations

##### References

7,279 citations

### "Target Location Using Dual-Beam Dir..." refers methods in this paper

...Based on the nearest-neighbor approximation of QPSK constellation, the probability of symbol error rate in [9] is...

[...]

163 citations

### "Target Location Using Dual-Beam Dir..." refers background in this paper

...Directional modulation (DM) is a transmitter technology that is capable of projecting digitally modulated information signals into prespecified spatial directions, while simultaneously distorting the constellation formats of the same signals in all other directions [1]....

[...]

136 citations

### "Target Location Using Dual-Beam Dir..." refers background in this paper

...Each of these modes in (2) can be excited independently by using a BM [6]....

[...]

105 citations

### "Target Location Using Dual-Beam Dir..." refers background or methods in this paper

...This approach adds additional flexibility as well as grossly simplifying the practical arrangements in [2] for achieving the same result....

[...]

...In [2] a DM method which mapped encoded orthogonal I, Q data streams onto two different antenna far field patterns was given....

[...]

...According to [2], the receive signal can be expressed as...

[...]

...In dual beam DM, [2], two excitation signals s1(t) = σ(t)×sinωt and s2(t) = δ(t)×cosωt are used to encode two transmit beams FΣ(φ) and FΔ(φ) , respectively, where σ(t) and δ(t) define the I and Q channel data information, ω is the carrier frequency, and φ is the azimuth angle of the receiver....

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###### Q2. What are the future works mentioned in the paper "Target location using dual beam directional modulated circular array" ?

The additional possibility of communicating with a suitable receiver equipped target was also described.