Achieving high gain and large bandwidth using hybrid dr antennas to feed short horns
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Achieving high gain and large bandwidth using hybrid DR antennas to feed short horns. Nasimuddin 1 and Karu Esselle 2 1 Institute for Infocomm Research, Singapore 2 Centre for Electromagnetic and Antenna Engineering Department of Electronic Engineering, Macquarie University

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Achieving high gain and large bandwidth using hybrid DR antennas to feed short horns

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Achieving high gain and large bandwidth using hybrid dr antennas to feed short horns

Achieving high gain and large bandwidth using hybrid DR antennas to feed short horns

Nasimuddin1 and Karu Esselle2

1Institute for Infocomm Research, Singapore

2Centre for Electromagnetic and Antenna Engineering

Department of Electronic Engineering, Macquarie University

Sydney, NSW 2109, Australia

Email: [email protected], [email protected]


Achieving high gain and large bandwidth using hybrid dr antennas to feed short horns

Outline

  • Introduction

  • Gain-Enhancement using Surface Mounted Short Horns (SMSH)

  • DRAs with SMSHs, designed for high gain

  • Hybrid dilectric resonator on patch (DRoP) antennas with SMSHs, designed for high gain over wide bandwidth

  • Conclusion


Achieving high gain and large bandwidth using hybrid dr antennas to feed short horns

Introduction

  • DRA has the advantages of low cost, compactness, high efficiency and a low profile.

  • Traditional microstrip antennas and dielectric resonator antennas have gains around 6 dBi to 8 dBi.


Achieving high gain and large bandwidth using hybrid dr antennas to feed short horns

  • To enhance the gain of DRAs, several methods have been employed:

  • offset dual-disk dielectric resonators (DR)

    • stacking parasitic DR with an air gap between radiating and parasitic DRs

  • Use of composite layered high permittivity DR

    • dielectric resonator loaded waveguide antenna with parasitic dielectric directors.

In most cases the gain enhancement is limited or the structure is complex. We propose to integrate DRAs and hybrid antennas with surface mount short horns to enhance gain significantly.


Achieving high gain and large bandwidth using hybrid dr antennas to feed short horns

Typical Structure of DRA integrated to a surface mounted short horn (SMSH)

Role of DRA:

Radiating Element

Feed to SMSH

  The SMSH is excited by the DRA.

q

Total Radiation is a combination of the radiation from DRA and the aperture of the SMSH.

Supporting Material of SMSH also effect the radiation properties.


Achieving high gain and large bandwidth using hybrid dr antennas to feed short horns

Design of SMSH for Maximum Gain

  • A SMSH, with an aperture coupled DRA, has been designed to give maximum gain at 6.0 GHz.

    • The distance (D) in the bottom of the SMSH from edge is less than or equal to o/4.

  • Select the shortest height of SMSH to achieve high gain, for a given taper angle of SMSH.

    • For this height, we investigate the gain variation with the taper angle of SMSH, to achieve highest gain.


Gain vs frequency for various smsh heights

Gain vs frequency for various SMSH heights


Gain variation with horn height around 6 ghz

Gain variation with horn height around 6 GHz

  • The gain increases with increasing height up to 0.15 o and then starts to decrease.

  • Smallest possible horn height with optimum gain is 0.15o at 6 GHz.

Maximum Gain for around 8.50 mm horn height


Gain vs frequency for different taper angles of smsh

Gain vs frequency for different taper angles of SMSH


Achieving high gain and large bandwidth using hybrid dr antennas to feed short horns

Fabricated DRA with SMSH

  • SMSH aperture is 48.1 mm  43.1 mm, ground plane is 60 mm  60 mm.

    • The rectangular DRA is located symmetrically over a rectangular aperture-coupled slot in the ground, which excited by a 50- microstrip line feed.

  • The rectangular DRA dimensions are: length = 12.8 mm; width = 7.3 mm; height = 6.35 mm; dielectric constant = 9.8; and loss tangent = 0.002.

    • Aperture coupled feeding structure dimensions are: aperture length = 6.4 mm; aperture width = 1.24 mm; stub length (s) = 1.8 mm; microstrip width = 1.16 mm; substrate dielectric constant = 3.38; loss tangent = 0.0022 and thickness = 0.508 mm.

  • Other horn dimensions are: area at lower (substrate) level = 27 mm  32 mm; taper angle = 45o: and height (H) = 8.1 mm (0.15o).

  • The total height of structure is only 0.172 o i.e. 8.61 mm at 6.0 GHz.

  • SMSH fabricated using solid Copper block


    Return loss of dra with smsh

    Return loss of DRA with SMSH

    • Measured return loss (RL) at 5.95 GHz is -13.5 dB and -10 dB RL bandwidth is 3.2 %.


    Gain enhancement

    Gain Enhancement

    Gain at 5.95 GHz:

    Theoretical gain : 8.8 dBi

    Measured gain : 8.5 dBi

    Measured gain of DRA alone is 3.7 dBi

    For SMSH fabricated from copper block

    Gain enhancement due to SMSH is 4.8 dB


    E plane radiation pattern at 5 95 ghz

    E-Plane Radiation Pattern at 5.95 GHz


    H plane radiation pattern at 5 95 ghz

    H-Plane radiation pattern at 5.95 GHz


    E plane radiation pattern at 6 ghz

    E-Plane radiation pattern at 6 GHz


    H plane radiation pattern at 6 ghz

    H-Plane radiation pattern at 6 GHz


    Achieving high gain and large bandwidth using hybrid dr antennas to feed short horns

    Another Prototype with DRA

    • To verify the effect of supporting material we fabricated another SMSH with foam as supporting material. It gives a further gain enhancement of around 1.5 dB.

    Gain of aperture coupled DRA with different horns (metal support and foam support)

    Gain at 5.95 GHz:

    Measured

    Metal gain is 8.50 dBi

    Air gain is 9.84 dBi

    Theoretical

    Metal gain is 8.80 dBi

    Air gain is 9.4 dBi


    Achieving high gain and large bandwidth using hybrid dr antennas to feed short horns

    To increase the bandwidth, we

    replaced the DRA with a hybrid

    Dielectric Resonator on patch (DRoP) antenna

    • Rectangular Dielectric Resonator on Patch with SMSH

    Feed Microstrip Line :

    W = 1.16 mm, stub length = 2.6 mm

    h = 0.508 mm, r = 3.38, tan = 0.0022

    Lower coupling aperture: 8.4 mm  0.9 mm

    Upper coupling aperture: 6.8 mm  0.7 mm

    Patch substrate: 12 mm  16 mm

    h = 0.762 mm, r = 2.45, tan = 0.001

    Patch : 9.05 mm  8.1 mm

    DRA :

    7.02 mm  12.0 mm

    h = 6.35 mm, r = 9.8, tan = 0.002

    q


    Achieving high gain and large bandwidth using hybrid dr antennas to feed short horns

    Fabricated DRoP with SMSH


    Achieving high gain and large bandwidth using hybrid dr antennas to feed short horns

    Theoretical and Experimental results of the rectangular DRoP antenna with SMSH

    Measured Impedance bandwidth is 24.4%

    Theoretical and measured Gain


    Achieving high gain and large bandwidth using hybrid dr antennas to feed short horns

    E & H-plane radiation patterns of the DRoP antenna with SMSH at 6.5 GHz

    E-Plane

    H-Plane


    Achieving high gain and large bandwidth using hybrid dr antennas to feed short horns

    • A Cross-Shaped Dielectric Resonator on Patch with SMSH


    Achieving high gain and large bandwidth using hybrid dr antennas to feed short horns

    Comparison of rectangular and Cross-DR

    on patch: VSWR

    The measured 2:1VSWR impedance bandwidth of the rectangular DR on patch is 6.04 to 8.0 GHz (27.9%) and cross DR on patch is 23% (6.06GHz to 7.64GHz).


    Comparison of rectangular and cross dr on patch gain

    Comparison of rectangular and Cross-DR on patch:

    Gain

    The measured gain of both antennas is more than 9dBi within the 2:1 VSWR impedance bandwidth.


    Achieving high gain and large bandwidth using hybrid dr antennas to feed short horns

    CONCLUSIONS

    • A theoretical and experimental study has been conducted on achieving high gain with wideband performance. Various DRAs and hybrid (DRoP) antennas coupled to SMSHs have been considered.

    • The DRoP antennas integrated to SMSHs have high gain, wide bandwidth and low profile. We achieved 28% 2:1 VSWR bandwidth, and gain over 9 dBi within this bandwidth, using a rectangular DRoP and SMSH.

    • We demonstrated a 4.9 dB gain improvement at 5.95GHz with a SMSH fabricated from a copper block. The total height of the structure is only 8.6 mm, i.e. 0.172 o.

    • The SMSH supporting material affects both the gain and radiation patterns.

    • The measured results in general show good agreement with results obtained using CST Microwave Studio.


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