Transcript
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
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