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LPY2 

 4  

INTRODUCTION 

This small log periodic antenna, which we call the ‘Logi’, is ideal for getting the 
maximum performance out of any UHF to low frequency microwave wireless 
system. Its directional properties “compresses” the signal into a powerful beam 
that is 4 times more powerful in the desired direction. It is the ideal antenna for 
scanners, wireless LANs, and other wireless devices. Its directional properties 
make it exceptionally well suited for point-to-point links! The units small size 
and wide bandwidth also make it ideal for feeding reflector antennas, such as 
the easily constructed corner reflector or grid that are discussed later in the 
manual. 

ANTENNA DESCRIPTION 

To start with, what is a log periodic antenna? The seeming simplicity of the log 
periodic antenna belies the remarkable features of the design. It uses a 
common transmission line to alternately feed a group of 1/2 

λ

 dipoles that are 

strung together. These antennas together display excellent radiation qualities 
over a wide range of frequencies as well as relatively uniform input impedances 
and  good VSWR characteristics. While the log periodic design has been 
around since the late 1950’s it has now been discovered to be at the cutting 
edge of antenna development. 

Looking at the physical layout of a 
log periodic antenna, one would see 
that it is comprised of multiple 
elements working together to provide 
a wide bandwidth of usable 
frequencies. The active (radiating or 
receiving radiation) portion of the 
antenna effectively shifts with 
frequency as one stage becomes 
‘more resonant’ than the next. The 
lowest operating frequency is 
determined by the longest element 
and the highest operating frequency 
is set by the shortest element. As the frequency of the transmission (or 
reception) increases, the active region of the antenna shifts forward to the 
shorter 1/2 

λ

 dipole elements or vice versa as the frequency decreases. 

Obviously then the ‘secret’ for proper operation must lie in the length and 
spacing of the antenna elements. These and other factors must be carefully 
chosen to cover the desired frequency range for the antennas’ application. 
Instead of forcing you to figure out all the math and spend hours experimenting, 
the creation of the Logi antenna (for frequencies between 900 and 2600 MHz) 
comes to the rescue!  

Feed
Point

Содержание LPY2

Страница 1: ...signal into a powerful beam that is 4 times more powerful in the direction you desire Easy hookup to your Receiver or Transmitter Small thin size with excellent broadband performance Solid 6 dB gain f...

Страница 2: ...LC1 Inductance Capacitance Meter RAMSEY AMATEUR RADIO KITS DDF1 Doppler Direction Finder HR Series HF All Mode Receivers QRP Series HF CW Transmitters CW7 CW Keyer CPO3 Code Practice Oscillator QRP P...

Страница 3: ...y Modification 7 Building a Corner Reflector 7 Building a Reflector Grid 9 LPY2 Return Loss Plot 10 Return Loss vs VSWR Chart 10 Warranty 11 KIT ASSEMBLY AND INSTRUCTION MANUAL FOR RAMSEY ELECTRONICS...

Страница 4: ...put impedances and good VSWR characteristics While the log periodic design has been around since the late 1950 s it has now been discovered to be at the cutting edge of antenna development Looking at...

Страница 5: ...al cable such as RG 142 141 and 085 semi rigid will also provide you with a good low loss connection as well as excellent high frequency characteristics Let s take a look at the circuit board for a mo...

Страница 6: ...s are much better than most other parasitic arrays with the same gain rating One drawback of the normal corner reflector arrangement is the fact that the active radiating or receiving element is usual...

Страница 7: ...rror to get things just right Use a piece of PVC pipe 1 2 to 7 8 will work well with a slot cut in the end just big enough to wedge the entire Logi in place The narrow front edge of the circuit board...

Страница 8: ...1 2 to 1 PVC coupler non threaded 1 3 4 to 1 PVC coupler threaded on the male 3 4 side only 1 can of PVC cement 3 4 minimum nylon wire ties 10 0 12 0 Cut a slot into the PVC boom Insert the Logi narro...

Страница 9: ...LPY2 9 LPY2 mounting Boom for a Grid Reflector LPY2 mounted on a Grid Reflector...

Страница 10: ...0 1 377 30 0 1 065 7 0 2 615 17 0 1 329 35 0 1 036 8 0 2 323 18 0 1 288 40 0 1 020 9 0 2 100 19 0 1 253 50 0 1 006 10 0 1 925 20 0 1 222 60 0 1 002 RETURN LOSS VERSUS VSWR CONVERSION CHART The LPY2 of...

Страница 11: ...be assured that the 1K ohm resistors are actually the missing 10 K parts Hum m m I guess the red band really does look orange Ramsey Electronics project kits are packed with pride in the USA If you b...

Страница 12: ...amsey RTS05 Small Diagonal Cutters Ramsey RTS04 OR Complete Soldering Tool Set RS64 2801 ADDITIONAL SUGGESTED ITEMS Optivisor Magnifier Headband Ramsey OPMAG Holder for PC Board Parts Ramsey RTS13 Des...

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