Log periodic antenna designing

Log Periodic Antenna

Group MembersSaad Rasheed Mughal

140173Usman Rafique 140281Mehran Meeran 140359

SynopsisUsman Rafique 140281 >Introduction Saad Rasheed Mughal 140173 >Calculation and construction

Mehran Meeran 140359 > Radiation Pattern And Matlab Muzammil Ali 140377 >Applications

IntroductionYour text hereo Log Periodic Antenna was invented by 

Dwight Isbell and Raymond DuHamel at the University of Illinois in 1958.

o A log-periodic antenna is a multi-element, directional, antenna designed to operate over a wide band of frequencies.

o The Individual Components are often Dipoles

Why it is called Log Periodic?The Lengths and spacings of elements

of Log Periodic Antenna increases logarithmicallyfrom one end to the other

Properties Multi Element

High BandwidthModerate Directivity Narrow Beam Antenna

Structure Log periodic antenna has an array of dipole which has their length according to logarithmic scale.

 Log periodic antenna is basically a wideband antenna because it has many dipole elements which are of different length, radiating different frequency.

In this the dipole array are cross connected to each other.

Dipoles are connected oppositely as to get maximum radiation towards the end of shortest

element

The upper and lower freq limits will be determined by lengths

of shortest and longest elements

Steps in Designing.

Impedance Calculations.

Min. Frequency : 900 MHzMax. Frequency : 1100 MHzBoom length : 14.32 inchGain : 8.98 dBElements : 9tau : 0.928sigma : 0.175

Design Parameters

Bandwidth Determination

Bandwidth (active region) : 1.49Bandwidth (structural) : 1.82Bandwidth (effective) : 1.22

ELEMENTS VALUESElement 1, Rod : 3.28 inch, Position : 0.00 inch, Diameter : 0.07 inchElement 2, Rod : 3.04 inch, Position : 2.29 inch, Diameter : 0.06 inchElement 3, Rod : 2.83 inch, Position : 4.42 inch, Diameter : 0.06 inchElement 4, Rod : 2.62 inch, Position : 6.39 inch, Diameter : 0.05 inchElement 5, Rod : 2.43 inch, Position : 8.22 inch, Diameter : 0.05 inchElement 6, Rod : 2.26 inch, Position : 9.92 inch, Diameter : 0.05 inchElement 7, Rod : 2.10 inch, Position : 11.50 inch, Diameter : 0.04 inchElement 8, Rod : 1.95 inch, Position : 12.96 inch, Diameter : 0.04 inchElement 9, Rod : 1.81 inch, Position : 14.32 inch, Diameter : 0.04 inch

Calculations of spacing between elements

Software Development and Construction of Log Periodic Dipole Antenna Using MATLAB

Calculating Antenna Parameters Manually are difficult. The Matlab Code was designed to calculate antenna parameter

and structure dimensions. It explore multiple approaches and reach a solution than

traditional programming languages. The MATLAB based program provides calculation in the fraction of

points which helps to design more accurate structure of LPDA antenna Calculations are cross checked manually

As well as on Matlab

3D Pattern 2D Pattern of Electric Field

Applications UHF Terrestrial TV

This sort of antenna can cover wide bandwidth  HF communications

it is used for diplomatic Traffic because of wide freqrange

EMC measurementsIt is used to enable operation and sensing of signals

over wide freq band Other than that it is used in

applications where we need directivity and high bandwidth

Electromagnetic Compatibility testing