Research Proposalin

ANTENNA DESIGN

Presented By : Naveen Kumar

Outline

Introduction

• Antennas for Mobile Handheld Devices

• Planar Inverted-F Antenna (PIFA) Structure

• Comparison between various antenna structures Problem Definition & Proposed Work Simulation Results with Conclusion Research Proposal Objectives Design Methodology

Introduction

An Antenna converts electromagnetic radiation into electric current, or

vice versa.

Need of Antenna :

For transmission and reception of the radio signal.

Antennas are required by any radio receiver or transmitter to couple its

electrical connection to the electromagnetic field. 

For electromagnetic waves carry signals through the air (or through

space) at the speed of light with almost no transmission loss.

Wireless performance is completely dependent on a high performance

antenna design and implementation. 

Antennas for Mobile devices

The type of antenna that is used with a particular type of phone is normally

determined by dimensional considerations and specific absorption rate (SAR)

regulations.

One has to make some kind of compromise among volume, impedance

bandwidth and radiation characteristics of an antenna while making the smallest

possible antenna.

Antenna used in mobile handheld devices supporting several frequency bands

can have one of the following structure :

• Single band Antenna

• Multiband Antenna

• Reconfigurable antenna

Antennas for Mobile devices (Contd.)

Following are main types of antennas used in cellular phones:

External Antennas

Monopoles (whips)

Helical

Internal Antennas

Microstrip antennas (MSA)

Planar inverted-F antennas (PIFA)t

GND

L

Wh

Monopole Antenna

Helical Antenna

Microstrip Antenna

Comparison between Different Antennas

Antenna Type/

Parameters

Monopole Slot Microstrip Patch

PIFA

Radiation Pattern

Omnidirectional Roughly Omnidirectional Directional Omnidirectional

Gain High Moderate High Moderate to high

Modeling & Fabrication

Modeling is somewhat difficult

Fabrication on PCB can be done.

Easier to fabricate and model

Easier fabrication using PCB

Applications Radio Broadcasting, vehicular antenna

Radar, Cell Phone base stations

Satellite Communication, Aircrafts

Internal antennas of Mobile phones

Merits Compact size,Low fabrication cost and simple to manufacture, Large bandwidth support

Radiation characteristics remains unchanged due to tuning, Design simplicity

Low cost, Low weight, Easy in integration

Small size, Low cost, Reduced backward radiation for minimizing SAR

Problems Difficult fabrication at higher frequencies (>3GHz)

Size constraint for mobile handheld devices

No bandpass filtering effect, surface-area requirement

Narrow bandwidth characteristic

Planar Inverted-F Antenna (PIFA)

PIFA is also referred to as short-circuited

microstrip antenna due to the fact that its structure

resembles to short-circuit MSA.

The shorting post near the feed point of PIFA

structure is a good method for reducing the

antenna size, but this result into the narrow

impedance bandwidth which is one of the

limitations.

By varying the size of the ground plane, the

bandwidth of a PIFA can be adjusted and

optimized.

The location and spacing between two shorting

posts can be adjusted accordingly.

L

W

Ground Plane

Radiating Patch

Feed point

h

LpWp

Typical PIFA Structure

Effect of Parameter Variation in PIFA

Parameters Effects

Length Determines resonance frequency

Width Control impedance matching

Height Control Bandwidth

Width of shorting plate Effect on the anti-resonance and increase bandwidth

Feed position from

shorting plate

Effect on resonance frequency and bandwidth

Scope of PIFA Structure

Now-a-days more and more radios are being integrated into single wireless

platform to allow maximum connectivity and ever increasing need of having

several functionalities in devices.

Multiband antenna approach using PIFA structure results in size reduction, low

SAR values, enhanced bandwidth coverage and good gain. These can be achieved

by employing several techniques to modify the basic structure and using ground

plane to support the main patch.

PIFA is also good choice to be used for LTE and WiMAX bands as for MIMO

applications, antennas small in size with good isolation are required.

Problem Definition

Single-band antenna supports only one or two frequencies of wireless service. And these days

more & more wireless standards are being supported by the devices. So they employ several

antennas for each standard.

This leads to large space requirement in handheld devices.

One foreseen associated problem with the antenna design for such devices is to cover 4G LTE

bands while still covering DCS 1800, PCS 1900, UMTS 2100, WiMAX and WLAN/Bluetooth

bands.

Thus, due to space constraints in mobile devices, covering multiple bands with a single antenna

structure is the need of the hour.

Proposed Work from the problem definition:

Therefore, the thesis work had been directed to make a multiband antenna and it was achieved

by using low profile antenna structures like PIFA with additional features to enhance the

bandwidth coverage and other important performance parameters.

Simulation Results

Detailed Dimensions

3D View in HFSS

Wp

Ls

Lg

h

Feed Wire

Ground Plane

Top Patch

L2

L1

Wg

L3

Wg2

L4

L5

Wg1

Lg1

Lp

Lg2

Ws

Fabricated Antenna

Return Loss (S11)

Simulated Measured

1900 MHz

1311 MHz

2834 MHz

5172 MHz

5596 MHz

2.40 GHz

5.40 GHz

Validation of Results

Antenna

Design /

Parameters

Volume

(mm3)

Resonant

Frequencies

Gain (dB) % Efficiency

(η)

Frequency Bands Covered

Existing

Design

1500 1.8 GHz, 2 GHz ,

2.4 GHz & 5 GHz

2.41, 2.86,

3.43 & 4.14

respectively

91, 92, 90 & 87

respectively

DCS (1710-1880 MHz), PCS (1880-

1990 MHz), UMTS (1900-2200

MHz), WiBro (2300 - 2390 MHz),

ISM / Bluetooth (2.4 - 2.48 GHz) and

WLAN (5.1-5.9 GHz)

Proposed

Design

1425 1.90 GHz, 2.40

GHz & 5.40 GHz

2.63, 4 & 6.18

respectively

96.9, 96.1 &

92.67

respectively

GPS L1 band (1575.42 MHz),

GLONASS-M L1 band (1602 MHz),

DCS (1800 MHz), PCS (1900 MHz),

UMTS (2100 MHz),

Wi-Fi/Bluetooth (2.4 GHz), 4G LTE

(1.7 GHz, 2.3 GHz & 2.6 GHz), &

WLAN (5.2 GHz).

ConclusionThe designed multi-band

antenna is very sensitive to any changes to the

dimensions of the structure including the ground plane.

Ground plane of the antenna is

used as a radiator resulting in overall size reduction and improvement in the operating bandwidth.

There is 5% reduction in

overall volume of the proposed antenna as

compared to Existing design.

Also there is significant

improvement in gain and radiation

efficiencies at obtained resonant

frequencies.

Research Proposal

The proposed design can be extended for

supporting MIMO applications for the

devices which supports LTE and WiMAX technologies.

The contribution of PIFA structure can be

incorporated in Smart antenna technology which uses tuning

methods.Body wearable antenna can be developed and analyzed for various emergency services,

medical, military, identification and

navigation applications.

Objectives

Reduce Overall Size

Improve Gain

Design Methodology

Selection of Design parameters.

Modeling of Antenna structure.

Simulating & Optimizing Design Parameters

Fabrication & Testing of Antenna

Comparison & Result Validation