# A Compact Wideband Active Two-Dipole HF Phased Array

^{1}

^{2}

^{*}

## Abstract

**:**

## 1. Introduction

## 2. Theoretical Model of the Antenna Array

_{1}and I

_{2}can be computed by the use of Kirchhoff’s law, where R1 and R2 are the 50 Ω output impedance of each driven element that is terminated at the 50 Ω input ports of the combiner, as given by Equations (2) and (3) below:

_{1}(R1 + 50)

_{2}(R2 + 50)

_{1}and I

_{2}are of identical magnitude, the radiation pattern of the array (assuming that the two driven elements are isotropic radiators) can be plotted by adding vectors using Equations (4) and (5), which have been derived from Figure 2 as follows:

- AF = Array factor
- θ = The radiation angle
- d = $\frac{\pi}{2}$
- ΔΦ = The phase difference feed

## 3. Design Considerations

- I is the current at the input port of the hybrid,
- V is the output voltage of the active antenna,
- Θ is the phase angle in degrees,
- R is the real part of the antenna’s active impedance, and
- X is the imaginary part of the antenna’s active impedance.

#### 3.1. Preliminary Testing in a Reflection-Free Environment

#### 3.2. Final Validation Using Other Antennas

## 4. Concluding Remarks

## Author Contributions

## Funding

## Institutional Review Board Statement

## Informed Consent Statement

## Data Availability Statement

## Conflicts of Interest

## References

- Economou, L.; Haralambous, H.; Pantjairos, C.; Green, P.; Gott, G.; Laycock, P.; Broms, M.; Boberg, S. Models of HF spectral occupancy over a sunspot cycle. IEE Proc. Commun.
**2005**, 6, 980–988. [Google Scholar] [CrossRef] - Haralambous, H.; Papadopoulos, H. 24-h HF Spectral Occupancy Characteristics and Neural Network Modeling Over Northern Europe. IEEE Trans. Electromagn. Compat.
**2009**, 59, 1817–1825. [Google Scholar] [CrossRef] - Haralambous, H.; Papadopoulos, H. 24-Hour neural network congestion models for high-frequency broadcast users. IEEE Trans. Broadcast.
**2017**, 55, 145–154. [Google Scholar] [CrossRef] - Mostafa, M.G.; Tsolaki, E.; Haralambous, H. HF spectral occupancy time series models over the eastern Mediterranean region. IEEE Trans. Electromagn. Compat.
**2016**, 59, 240–248. [Google Scholar] [CrossRef] - Taguchi, M.; Era, K.; Tanaka, K. Two element phased array dipole antenna. ACES J.
**2007**, 22, 112–116. [Google Scholar] - Bingeman, G. Phased Array Adjustment for Ham Radio. Available online: https://ftp.unpad.ac.id/orari/library/library-sw-hw/amateur-radio/ant/phaseshift/array.htm (accessed on 31 July 2021).
- Tomas, H. 2m Phased Vertical Antenna. Issuu. 2021. Available online: https://issuu.com/jw9w2ws/docs/2meterphasedvertant (accessed on 31 July 2021).
- Straw, R. The ARRL Antenna Book; ARRL: Newington, CT, USA, 2009. [Google Scholar]
- Balanis, C. Antenna Theory; Wiley: Hoboken, NJ, USA, 2016. [Google Scholar]
- Kraus, J.; Marhefka, R.; Khan, A. Antennas and Wave Propagation; McGraw-Hill: New Delhi, India, 2002. [Google Scholar]
- Von Aulock, W. Properties of Phased Arrays. Proc. IRE
**1960**, 48, 1715–1727. [Google Scholar] [CrossRef] - Constantinides, A. Collinear Arrays, 1st ed.; ARRL Antenna Compendium: Newington, CT, USA, 2002; Volume 7, pp. 37–39. [Google Scholar]
- Katagi, T.; Ohmine, H.; Miyashita, H.; Nishimoto, K. Analysis of Mutual Coupling Between Dipole Antennas Using Simultaneous Integral Equations With Exact Kernels and Finite Gap Feeds. IEEE Trans. Antennas Propag.
**2016**, 64, 1979–1984. [Google Scholar] [CrossRef] - Balanis, C. Antenna Theory-Analysis and Design, 3rd ed.; Wiley: Hoboken, NJ, USA, 2005; pp. 479–481. [Google Scholar]
- Kraus, J. Antennas, 2nd ed.; Mcgraw-Hill: New York, NY, USA, 1988; pp. 424–426. [Google Scholar]
- Nxp.com. 2021. Available online: https://www.nxp.com/docs/en/data-sheet/BF245A-B-C.pdf (accessed on 30 July 2021).
- Minicircuits.com. 2021. Available online: https://www.minicircuits.com/pdfs/MAR-8A.pdf (accessed on 30 July 2021).
- Minicircuits.com. Mini-Circuits. 2021. Available online: https://www.minicircuits.com/WebStore/modelSearch.html?model=PSCQ-2-51W%2B (accessed on 30 July 2021).
- HE016 | Brochure and Datasheet. Rohde-Schwarz.com. 2021. Available online: https://www.rohde-schwarz.com/brochure-datasheet/he016/ (accessed on 30 July 2021).
- Manualslib.com. R&S EM510 Manual Pdf Download | ManualsLib. 2021. Available online: https://www.manualslib.com/manual/1106858/RAnds-Em510.html (accessed on 30 July 2021).
- Cdn.Rohde-Schwarz.com. 2021. Available online: https://cdn.rohde-schwarz.com/pws/dl_downloads/dl_common_library/dl_brochures_and_datasheets/pdf_1/ZS129x_bro_en.pdf (accessed on 30 July 2021).

**Figure 1.**The equivalent circuit of a quarter-wavelength phased array with 90° difference feed under ideal conditions.

**Figure 3.**Radiation patterns of two isotropic sources spaced from 0.05 λ to 0.5 λ with a 90° phase difference feed.

**Figure 5.**Oscilloscope output from simulation at 25 MHz based on mutual impedance of the two driven elements of Figure 4 (oscilloscope 0.2 V per division) versus high impedance (oscilloscope 0.5 V per division).

**Figure 6.**The effect of mutual coupling on the 0.25 λ array radiation pattern under ideal and real conditions.

**Figure 9.**The isolation performance of the LNA simulated at 25 MHz. Top waveforms are at 0.2 V per division; bottom waveforms are at 0.5 V per division.

**Figure 15.**The free-space azimuthal response for the horizontal two-dipole phased-array antenna at 25 MHz and 30° elevation angle as simulated by EZNEC with gain = 7.23 dB, F/B = 19.79 dB, HPBW = 44.5°.

**Figure 17.**(

**a**) 2–30 MHz R&S high angle, (

**b**) 2–30 MHz array East–West, (

**c**) 2–30 MHz R&S high angle, and (

**d**) 2–30 MHz array North–South.

Impedance (Ω) | Freq. (MHz) | E-Plane HPBW (Degrees) |
---|---|---|

80 + j43 | 30 | 77 |

53 − j160 | 25 | 81 |

32 − j412 | 20 | 84 |

17 − j764 | 15 | 86 |

7 − j1374 | 10 | 88 |

1.9 − j3016 | 5 | 90 |

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**MDPI and ACS Style**

Constantinides, A.; Haralambous, H. A Compact Wideband Active Two-Dipole HF Phased Array. *Appl. Sci.* **2021**, *11*, 8952.
https://doi.org/10.3390/app11198952

**AMA Style**

Constantinides A, Haralambous H. A Compact Wideband Active Two-Dipole HF Phased Array. *Applied Sciences*. 2021; 11(19):8952.
https://doi.org/10.3390/app11198952

**Chicago/Turabian Style**

Constantinides, Antonios, and Haris Haralambous. 2021. "A Compact Wideband Active Two-Dipole HF Phased Array" *Applied Sciences* 11, no. 19: 8952.
https://doi.org/10.3390/app11198952