DESIGN OF MINIATURIZED ULTRA-WIDEBAND CONICAL SPIRAL ANTENNA USING HFSS

Under Guidance of T Anusha LalithaAssistant Prof. TCE, BMSCE

BySandeep Kumar P 1BM11TE045Satish Kumar T V 1BM11TE048Sharath Chandran C K 1BM11TE406Santosh Patil 1BM12TE409

Introduction• What is an ANTENNA ???

Antenna CharacteristicsAn antenna is a device that is made to efficiently

radiate and receive radiated electromagnetic waves. There are several important antenna characteristics that should be considered when choosing an antenna for your application as follows: • Antenna radiation patterns• Power Gain• Directivity• Polarization

Conical Spiral AntennasHigh data rate and wider bandwidth requirements for

data\video transfer and growth in number of users lead to increase operating frequencies of these systems to microwave and millimeter-wave frequencies.

Spiral antennas are one of frequency independent antennas with wide bandwidth and good pattern efficiency in compare with other antennas.

Desirable radiation characteristics can be achieved by changing circular radius r, number of turns N and the width of them W.

Types of conical spiral antenna

Log Spiral Antenna

Archimedean Spiral Antenna

Sinuous Spiral Antenna

Construction of Spiral Antenna

Creating First Arm

The second arm is constructed by Rotating the first arm by π radians

Log Spiral Antenna Parameters

Wherero = inner radiusa = Ln( ExpansionRatio)/2pi

The pitch angle Ψ related to expansioncoefficient a bytan Ψ = r/(da/dΦ) = 1/athe design ratio τ is defined to be less than 1 and is given by

this is ratio of OA/OB of the figure and is the ratio of the radii for one turn of the log spiral curve.

Conical Archimedean Antenna Parameters

The centerline of the antenna is defined by

ρ = aφ

The first arm, which begins along the x-axis in this example, is defined by the edges

Conical Sinuous Antenna Parameters

where Φ and r are polar coordinatesp is cell number and τ is growth rate

the design parameters may be independent of p to form a LP structure that is periodic function of logarithm of radius r .

HIGH FREQUENCY STRUCTURE

SIMULATOR

HFSS….???Uses Finite Element Method to solve

Electromagnetic structureUsed for antenna design and design of complex

RF electronic circuit elements including filters, transmission lines, etc.

HFSS is essential for designing high-frequency and/or high-speed components used in modern electronics devices

FeaturesPowerful drawing capabilities to simplify design

entryComputes s-parameters and 3D passive

structuresAdvanced materialsModel Library-including spiral inductorCalculate far-field patternsWideband fast frequency sweep Create parameterized cross section models- 2D

models

HFSS Analysis Design Flowchart

Construct Geometry

(User Input)

Define Volume Conditions

(User Input)

Define Surface Conditions

(User Input)

2D Excitation Solution

(Automatic)

3D Mesh Generation

(AutomatIc)

Solve 3D Matrix

(Automatic)

View/Plot S-Parameters

(User Input)

View/Plot Fields

(User Input)

PRE-PROCESSING SOLUTION POST-PROCESSING

Define Solution Requirements

(User Input)

Applications

AntennasMicrowave transitionsWaveguide componentsRF filtersThree-dimensional discontinuitiesPassive circuit elements

RESULTS

RETURN LOSS

LOG SPIRAL

ARCHIMEDEAN

INPUT IMPEDENCE

LOG SPIRAL ARCHIMEDEAN

Z PARAMETERS

3D GAIN OF RHCP

LOG SPIRAL

ARCHIMEDEAN SINUOUS

3D GAIN OF LHCP

LOG SPIRALARCHIMEDEAN SINUOUS

2D GAIN OF RHCP

LOG SPIRAL

ARCHIMEDEAN

SINUOUS SPIRAL

2D GAIN IN LHCP

LOG SPIRAL

ARCHIMEDEAN

SINUOUS

Features of Conical Spiral Antenna• Conical spiral antennas are true frequency

independent antennas Cover the required 6.5 : 1 frequency range • Relatively constant beam characteristics

(beamwidth, polarization, ...) • Usefully wide beamwidth while maintaining

other desirable properties • Low ellipticity (axial ratio) • Good polarization purity (wide band) • Low mutual coupling in array

In addition to the above performance requirements, the antenna would be versatile in the following ways:

• Inexpensive• High power levels (100 W) as sensor• CW and Pulse Applications• Use in confined spaces• Provides Circular Polarization

Antenna characteristics with frequency

• Nearly constant beam pattern• Low back-lobe at all but lowest frequency• Relatively small, smooth impedance variation• Good axial ratio maintained• Spiral features

1. Low mutual coupling2. Polarisation purity3. Good isolation

Applications

•Measurement of electromagnetic (EM) Shielding Effectiveness in confined spaces.• As facility-embedded EM sensors for

receive antennas.•Wideband communications.•Monitoring of the frequency spectrum.

Applications(contd.)

• A pair of spiral antennas are used in this application, having identical parameters except the polarization, which is opposite (one is right-hand, the other left-hand oriented).• Spiral antennas are useful for microwave

direction-finding.

CONCLUSION :

The main goal is to UWB conical log spiral antenna is to transmit data at very high data rates by sending pulses of energy rather than using a narrow band frequency carrier.

The main objective was to get information of the near- and far-field characteristics and on the input impedance for a wide range of parameters is presented in a form suitable for use in the design of practical antennas.