RadioReference on Facebook   RadioReference on Twitter   RadioReference Blog
 

Go Back   The RadioReference.com Forums > Scanners, Receivers and Related Equipment Forums > Antennas and Associated Hardware > Build Your Own Antenna

Build Your Own Antenna - Discuss topics for building your own antenna.

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
  #1 (permalink)  
Old 10-29-2014, 4:18 AM
Member
   
Join Date: Feb 2011
Location: italy
Posts: 39
Default My new homemade LPDA (and the first)

This is my new LPDA homemade antenna for UHF-AIR (225-400 MHz) The design was taken from an old magazine and recalculated for the frequencies of interest.
Attached Images
 
Reply With Quote
Sponsored links
  #2 (permalink)  
Old 10-29-2014, 7:07 AM
Member
  Premium Subscriber
Premium Subscriber
Amateur Radio Operator
Amateur Radio
 
Join Date: Apr 2003
Location: Sand Springs OK
Posts: 966
Default

Looks cool, now bring the details: materials, construction, performance, who are you so interested in that it made you build this?
Reply With Quote
  #3 (permalink)  
Old 10-29-2014, 8:29 AM
Member
   
Join Date: Jun 2006
Posts: 5,757
Default

I don't think that will work the way you made it. That's a split boom design where the boom is the feedline and every other set of elements need to reverse phase. It appears you have all elements on one boom pointing up and all elements on the other boom pointing down and you need to reverse every other set of elements.

Starting at the back or longest elements, if the boom facing you in the picture has an element going up, then the next shortest element will point down and the next smallest will point up, etc. The boom facing away from you would start with the longest element pointing down and the next shortest pointing up, etc.

The way its put together now is just a large nest of dipoles with no directionality.
prcguy


Quote:
Originally Posted by red-dog View Post
This is my new LPDA homemade antenna for UHF-AIR (225-400 MHz) The design was taken from an old magazine and recalculated for the frequencies of interest.
Reply With Quote
  #4 (permalink)  
Old 10-29-2014, 9:32 AM
Member
  Premium Subscriber
Premium Subscriber
Amateur Radio Operator
Amateur Radio
 
Join Date: Dec 2009
Location: Michigan
Posts: 176
Default My Log-periodic Yagi

PRCGUY is correct. See the pictures of my 2 meter LPY as examples. Also, if the aluminum boom and/or elements are anodized you must remove it from element and feed-line contact points for maximum conductivity.

Last edited by rivardj; 08-14-2016 at 1:02 PM..
Reply With Quote
  #5 (permalink)  
Old 10-30-2014, 4:57 AM
Member
   
Join Date: Feb 2011
Location: italy
Posts: 39
Default more images LPDA 225-400 MHz

I'm posting more photos to give a better idea of ​​the construction of this system LPDA. The elements are aluminum 8 mm and the two boom are 20 mm with a length of 1.50 m.
Attached Images
     
Reply With Quote
Sponsored links
  #6 (permalink)  
Old 10-30-2014, 9:01 AM
Member
   
Join Date: Jun 2006
Posts: 5,757
Default

That is very nice construction and a beautiful looking antenna, however it will not function the way you made it. Look at the pictures posted by rivardj that shows how the elements should be arranged.

red-dog has all the elements on one boom facing the same direction and instead, every other element must point the opposite direction. Please read the other posts describing this, otherwise the antenna will not work as a Log Periodic and will be nothing more than random bits of aluminum in the sky.

I understand there may be a language problem understanding my description but please look up some pictures of other Log Periodic antennas on the Internet to see what we are discussing.
prcguy

Quote:
Originally Posted by red-dog View Post
I'm posting more photos to give a better idea of ​​the construction of this system LPDA. The elements are aluminum 8 mm and the two boom are 20 mm with a length of 1.50 m.
Reply With Quote
  #7 (permalink)  
Old 10-31-2014, 3:31 AM
Member
   
Join Date: Feb 2011
Location: italy
Posts: 39
Default

I do not understand the difference between my antenna and that of Rivardj, the arrangement of the elements seem the same. . . .
Reply With Quote
  #8 (permalink)  
Old 10-31-2014, 3:48 AM
Member
   
Join Date: Feb 2011
Location: italy
Posts: 39
Default esempio

Perhaps this design is more explicit.
Attached Images
 
Reply With Quote
  #9 (permalink)  
Old 10-31-2014, 3:53 AM
Member
   
Join Date: Feb 2011
Location: italy
Posts: 39
Default example

This is perhaps clearest example
Attached Images
 
Reply With Quote
Sponsored links
  #10 (permalink)  
Old 10-31-2014, 8:38 AM
Member
   
Join Date: Jun 2006
Posts: 5,757
Default

The picture you posted is the correct way to arrange the elements and does not match what you built.

Looking at the left side boom in the picture the element closest to the viewer points up and the matching element on the right side boom points down. Looking at the next set of elements away from the viewer, the left boom element now points down and the right boom element points up. The last set of elements the farthest away from the viewer where the coax exits the left boom element points up again and the right boom points down.

If you look at your completed antenna with the same view, all the elements on the left boom point up and all the elements on the right boom point down, they do not reverse like the picture you posted.

Looking at your construction it should be easy to take some the antenna apart and arrange the elements to match the picture.
prcguy


Quote:
Originally Posted by red-dog View Post
This is perhaps clearest example
Reply With Quote
  #11 (permalink)  
Old 10-31-2014, 10:50 PM
737mech's Avatar
Member
  Premium Subscriber
Premium Subscriber
Amateur Radio Operator
Amateur Radio
 
Join Date: Aug 2006
Location: Clark County, NV.
Posts: 1,427
Default

Looks cool but what are you using for numbers (spacing and length)? I agree with prcguy you have to change the elements they all can't be up on one boom and down on the other. You have to change the arrangement one up one down and it opposes the other boom one down one up.
__________________
In Omnia Paratus!

Et fac magnus Americae
Reply With Quote
  #12 (permalink)  
Old 11-02-2014, 1:58 AM
Member
   
Join Date: Feb 2011
Location: italy
Posts: 39
Default

I have done a mistake by 'stupid', has been the rush to mount the antenna or old age? Thanks for the advice, today I will to move items !!!!!
Reply With Quote
  #13 (permalink)  
Old 11-02-2014, 10:06 AM
Member
   
Join Date: Jun 2006
Posts: 5,757
Default

It would be interesting to test the antenna as you built it then test again after its fixed. Please let us know how it works.
prcguy

Quote:
Originally Posted by red-dog View Post
I have done a mistake by 'stupid', has been the rush to mount the antenna or old age? Thanks for the advice, today I will to move items !!!!!
Reply With Quote
  #14 (permalink)  
Old 11-02-2014, 11:45 AM
Member
  Audio Feed Provider
Audio Feed Provider
Amateur Radio Operator
Amateur Radio
 
Join Date: Dec 2007
Location: Eastern, NC
Posts: 2,364
Default

where did you get the square aluminum tubing and the element materials? i would love to try this as a first antenna
__________________
Scanners: BCT-15, Pro-106, Whistler 1040
Radios: Icom 3161, Connect Systems CS580
John 15:13 - Greater love hath no man than this, that a man lay down his life for his friends.
Reply With Quote
  #15 (permalink)  
Old 11-02-2014, 12:28 PM
mm mm is offline
Member
   
Join Date: Dec 2002
Posts: 521
Default

Order Aluminum Square Tube Alloys 6061, 6063 in Small Quantities at OnlineMetals.com

Online metals has the best selection and prices for square tubing for booms, for the elements I use dx engineering.

DX Engineering Aluminum Tubing - Free Shipping on Orders Over $99 at DX Engineering
Reply With Quote
Sponsored links
  #16 (permalink)  
Old 11-03-2014, 2:55 AM
Member
   
Join Date: Feb 2011
Location: italy
Posts: 39
Default

The error has been corrected, now LPDA this should work. . . was fixed to the mast, and is fed with 75 ohm cable TV, the connector is an 'F'
├┼┼┼│
ALUMINIUM BOOM - mm. The 20x20 mm. 1500
ELEMENTS OF ALUMINUM TUBE 8
I'm sorry but I do not have proper equipment to be able to give more technical information, is the only tool. . . the scanner, I will hear something in the next few days.
Reply With Quote
  #17 (permalink)  
Old 11-03-2014, 5:46 PM
737mech's Avatar
Member
  Premium Subscriber
Premium Subscriber
Amateur Radio Operator
Amateur Radio
 
Join Date: Aug 2006
Location: Clark County, NV.
Posts: 1,427
Default

I have no doubts you will hear something, please tell us bands where you notice improved activity,(vhf/uhf/400/800/900) also try to point the antenna toward your city or area of interest. Please if you could post the dimensions of the reflectors and how far apart they are along the boom.
__________________
In Omnia Paratus!

Et fac magnus Americae
Reply With Quote
  #18 (permalink)  
Old 11-05-2014, 12:17 AM
Member
   
Join Date: Feb 2011
Location: italy
Posts: 39
Default

Given the short time available to me, I work radio normally around 14.00 Italian time and between 250 and 280 MHz listening regular air communications, will post soon the construction scheme.
Reply With Quote
  #19 (permalink)  
Old 11-05-2014, 2:49 AM
majoco's Avatar
Member
   
Join Date: Dec 2008
Location: New Zealand
Posts: 2,254
Default

LPDA calculator....

Online Calculator .:. LPDA - Logarithmic Periodic Dipole Antenna
__________________
Cheers - Martin ZL2MC - Palmerston North
Reply With Quote
  #20 (permalink)  
Old 11-06-2014, 1:27 AM
Member
   
Join Date: Feb 2011
Location: italy
Posts: 39
Default

Thanks but I already knew this site, my project was born many years ago, back when there was no internet and it was done on the basis of some data in the book Nerio Blacks (I4NE) entitled Antennas, design and construction.
Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On



All times are GMT -5. The time now is 5:15 AM.


Powered by vBulletin® Version 3.8.2
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
All information here is Copyright 2012 by RadioReference.com LLC and Lindsay C. Blanton III.Ad Management by RedTyger
Copyright 2015 by RadioReference.com LLC Privacy Policy  |  Terms and Conditions