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Miniature Antenna: Results and Proposed Work. March 2008. Outline. 916 MHz antenna prototypes and results 2.2 GHz, 2.4 GHz antenna prototypes and results 433 MHz antenna prototypes and results Proposed New Research. Simulation and Measurement of S11.

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Miniature Antenna: Results and Proposed Work

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Miniature Antenna:Results and Proposed Work

March 2008


  • 916 MHz antenna prototypes and results

  • 2.2 GHz, 2.4 GHz antenna prototypes and results

  • 433 MHz antenna prototypes and results

  • Proposed New Research

Simulation and Measurement of S11

The volume of the antenna with its ground plane is 0.024 λ  0.06 λ  0.076 λ,

where λ = 372.5 mm for 916 MHz antennas.

916 MHz antenna, prototype and test results

916 MHz antenna, Gain measurements

Half wave dipoles

916 MHz FICA

Half wave dipoles

916 MHz FICA

2.2 GHz FICA

Bandwidth = 14 MHz

2.45 GHz FICA

Bandwidth = 3 MHz

S11 of 2.2 GHz & 2.45 GHz FICA

Total volume including ground plane:

0.09 λ x 0.09 λ x 0.025 λ

λ = 136.36 mm@2.2 GHz

λ = 122.44 mm@2.45 GHz

2.2GHz FICA: 98% available power transmitted

2.45GHz FICA: 92% available power transmitted

2.2 GHz FICA Gain Test (II)

Calibrate using ½ wave dipole

Difference between FICA and ½ dipole is -7dB; Polarization demonstrates functionality


Half wave dipole

68 mm

0.09 λ x 0.09 λ x 0.025 λ

12 mm x 12 mm x 3.5 mm

433 MHz Dielectric Loaded Miniature Antenna Results

At 433 MHz,


This antenna

can work with

a PCB board of

0.11λ x 0.037λ

Initial test:

-5dB Bandwidth

is 8 MHz

Further design needed for 10MHz bandwidth




Commercial Chip Antennas (Antenna Factors, Co.) need a ground plane to function properly
















SMA fed through a hole

λ= 32.75 cm ( 916 MHz )

Antenna 1~4, commercial chip antenna.

Antenna 5: Our FICA antenna

FICA Outperforms Commercial

  • Antenna 1-4 are commercial antennas. Antenna 5 is our FICA.

  • Antenna 1 is the exact design given by spec sheet,

  • Antennas 1-3: The feeding cable is along the same direction as the feeding line, which helps antenna radiation, effectively increasing antenna size.

  • To eliminate this effect, feeding line is perpendicular to the ground plane. This was done for Antenna 4, notice enormous performance drop.

  • Our FICA (Antenna 5) has substantially better performance than commercial antennas, especially with when feed is not part of the system (4) where the improvement is by more than 23dB (200 times).

Proposed Research for Ultra-Small Antennas

Task I: Design of Helical (FICA) Style Ultra-Small Antenna for Requested Specifications (400MHz resonance, 10MHz BW)

  • Ultimate optimization goal:

    • Maximum achievable bandwidth (10 MHz or more Bandwidth at 400 MHz with10 dB return loss )

    • minimum antenna volume (2 parts)

      • Part1: the component which we called “antenna”,

      • Part2: the “virtual or image antenna”-----ground plane

        (ground plane will be smaller than the current prototype at 400 MHz)

    • highest gain (-1 to -2 dBi)

    • highest achievable efficiency (40%<efficiency<60%)

Proposed Research for Ultra-Small Antennas:Realize Design Goals

  • We will optimize the following parameters for FICA:

    • Determine helix shapes for wire antenna families (i.e. FICA): pitch, leaning angle, cross-section area of coils, helix length, tapping point.

    • Determine geometry of ground plane: ground plane size, feeding positions and FICA position on the ground plane.

    • Optimize dielectric block: Use dielectric to increase capacitance to ground, not the intercoil capacitance of FICA to minimize the coil length

  • These design goals will be realized with a synergistic approach using experiment and theory:

    • We will fabricate and test designs

    • We will use finite element (HFSS) simulation to help guide experimental program.

Proposed Research for Ultra-Small Antennas

We also propose to develop circuit models of FICA for antenna-RF circuit co-design, which will maximize performance on system level.

For example, for a FICA at 916 MHz (Fig a), we developed an equivaleng circuit to represent the antenna’s impedance matching, radiation resistance, and resonance. The circuit may look like the one in Fig. b. With the help of circuit b, we could optimize system gain, and sensitivity for transceivers.



Proposed Research for Ultra-Small Antennas

Testing plan:

Will have access to a world class anechoic camber at the FDA White Oaks Facility

Antenna measurements at the FDA will be very accurate and help evaluate with precision the gain performance of the various designs.

We will regularly compare our antenna prototypes with commercially available antennas.

Comparisons will require building test platforms for commercial antennas, as well as our own.

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