Multi- -Function Function Microstrip Microstrip Multi Patch - - PowerPoint PPT Presentation

Multi Multi-

• Function

Function Microstrip Microstrip Patch Antennas Partially Patch Antennas Partially Filled with Left Filled with Left-

• Handed

Handed Structures Structures

• !"#$%&'(!')&'(!'

COST ASSIST Workshop, Cyprus, April 2008

2

Outline Outline

Introduction

Objective Terminology

TL Model of proposed patches Triple-frequency and dual-mode patch antenna Dual-frequency patch antenna Polarization diversity

Multi-frequency and dual polarization Dual-frequency CP patch antennas

Conclusion

3

Introduction Introduction

Wireless services have grown dramatically in the last years. Objective: Development multi-function patch antennas

Simultaneous operation at different frequencies. Patch-like and monopolar (null at broadside) radiation patterns at different working frequencies. Arbitrary selection of frequencies. Compact antennas Integration into handheld devices.

Terminology:

(a) RH (Right-Handed) or Conventional Materials:

• (E, H, ) form a right-handed triplet.
• (E, H, S) form a right-handed triplet.
• Equivalent circuit of a RH TL section: series L and shunt C.
• > 0 and proportional to

(b) LH (Left-Handed) or DNG (Double Negative) Metamaterials:

• (E, H, ) form a left-handed triplet.
• (E, H, S) form a right-handed triplet.
• Equivalent circuit of a LH TL section: series C and shunt L.
• < 0 and proportional to 1/

4

TL TL Model Model of

• f

proposed proposed patches patches

Proposed approach:

RH+LH+RH TL Resonant condition:

nL = n

RHd + n LH = n

with RH k1f and LH k2/f

Additional modes below the conventional frequency are obtained:

• |RHd| < |LH| n = –1 (nL = -)
• |RHd| = |LH| n = 0 (nL = 0)

The conventional modes are also present:

• |RHd| > |LH| n = +1, +2, …

5

Triple Triple-

• frequency

frequency antenna antenna

The simplest antenna based on previous model is a squared patch partially filled with 2 LH cells. The LH cells are implemented by using a rectangular version

• f the Sievenpiper’s mushroom

structure:

Slots are made inside the patch to define the cells. Each cell is grounded with a via.

Modes n = -1, 0 , +1 are excited.

n = ± 1 are patch-like modes. n = 0 is a monopolar mode.

6

Triple Triple-

• frequency

frequency antenna antenna

7

Dual Dual-

• frequency

frequency antenna antenna

8

Polarization Polarization diversity diversity

In all the previous designs, only one polarization has been used (TMn0 modes). It is possible to excite modes with two orthogonal polarizations (TMn0 and TM0m modes). This can be used to develop patch antennas with interesting properties:

Dual-band CP antennas:

• With two feeds and external circuitry.
• With one feed.

Quad-band antennas with two orthogonal polarizations (frequency and/or polarization diversity):

• With two ports and high isolation between ports. Application:

self-diplexed patch antennas.

• With one port.

9

Polarization Polarization diversity diversity

10

Multi Multi-

• freq

freq. . and and dual dual-

• polarization

polarization

11

Multi Multi-

• freq

freq. . and and dual dual-

• polarization

polarization

12

Dual Dual-

• freq
• freq. CP

. CP patches patches

Two approaches:

(a) Two ports and external circuitry. (b) Perturbations in the patch:

• Slightly rectangular patches (W

L)

• Small squares.
• Etc.

13

Conclusion Conclusion

Multi-frequency patch antennas have been developed by partially filling a conventional patch with left-handed cells. The working frequencies can be arbitrarily chosen and they depend on the lengths of the patch and the cells. These antennas can be used for interesting applications: polarization/frequency diversity, dual-band CP patch antennas, self-diplexed patch antenna, etc.

14

THANK YOU