"My Very first Dipole Antenna"

[TUSHAR GUPTA]

Hi, 

This post will help the novice who wants to build their very first Dipole antenna. Before starting a brief overview about how I got one of my firsts. My JOTA 

40 Rx kit was long waiting for assembly, this wait got over when I came to Bangalore and met VU2DEV (OM Dev Prabhu). I told him that I want a home brew 

Dipole antenna but I don't know how to make one. He gave me a date and asked me to come to his workshop with the required stuff, and assured me that I will 

build my own antenna and it will be as good to listen many a Distant station.

The day had arrived and I reached the work shop with the required stuff (It is advised to take a metre or two of extra wire/cable):

1. 42ft / 12.8m of RG-52 Coaxial cable, for a 40m band dipole cable length should be in multiples of 42ft (I got it for Rs.15/m in Bangalore, superior 

quality can be got for Rs. 20/m)

2. 70 ft / 21.3m of 1 mm^2 wire (I got it  for Rs.9/m same place)

3. UHF male connector with reducer/adapter (Got it for Rs.50, Superior quality can be got for around Rs.100)

It is advised that the antenna construction is performed under supervision of an experienced HAM, so as to avoid making avoidable mistakes. (Generally 

mistakes are made while making connections or with antenna length)

Just as I entered the workshop, OM DEV inspected the stuff and started giving me instructions, and in just under 3 hours, my very own Dipole antenna was 

ready in my hand.

Steps of construction (In this tutorial Antenna wire will be refered to as 'wire' where as the coaxial cable will be referred to as 'cable'):

1. Measure the length of both the wire as well as the cable, and ensure that it may be more but not less than the minimum requirement.

2. Now "CAREFULLY" strip one end of the Coaxial cable, ensure that you do not cut the mesh of the shield. 

3. After removing the jacket of the cable, remove the tangles of the mesh with the help of a pin (A safety pin will do).

4. Divide the separated strands of the mesh into two groups and roll them individually.

5. Also peel of the second jacket and uncover the central wire.

 

6. Now take the UHF male connector and with a file scratch its outer area near the four holes, afterwards scratch the central pin from the end where it is 

half cut.

7. Now, keep the following items for tinning, i.e. UHF male connector and Stripped end of Coaxial cable (Coax has three elements to be tinned 1st the central 

core, 2nd & 3rd is the two rolled sides of the mesh strands).

8. Carefully apply a layer of solder on all these elements (on UHF male at points where it was scratched and on cable along the uncovered length), this 

process is called tinning.

9. After tinning insert the stripped end of the cable into the adapter/reducer in a way that it can be screwed into the UHF male when it is soldered to the 

cable ends.

10. Now insert the cable into the UHF male keeping in mind that the two rolled strands of wire enter two holes in the UHF male separated by an angle of 180 

deg where as the central cable should go inside the pin of the UHF male.

11. Now solder the central wire to the pin where as the two strands to the wall of the UHF male outside the holes.

12. Screw the adapter into the UHF male.

13. Now, One end of the feed coax cable is ready.

14. Cut the wire exactly into two halves, peel 1 end each from the 2 halves, roll them and tin them.

15. Repeat Steps 2,3 and 4 for the other end of the coax cable, except in step 4 roll the strands into 1 and then tin the core as well as the rolled wire.

16. Take a 6" X 4" PCB or MICA board and drill 4 holes in a diamond fashion keeping the board in Landscape orientation.

.__________.

|                   |

|        4         |

|2           3 |

|        1         |

:__________:

17. In hole number 1 takeout the coaxial cable while tying a knot around the edge of the board and leaving the stripped end outside the knot.

18. Repeat steps 17 for the two halves of the cable and knot them to holes 2 & 3.

19. Now solder the core of the cable to one of the wire halves and the rolled strands with the other half.

20. With this your very first dipole Antenna for 40m is ready.

PLEASE NOTE

 a) Half wave dipole Length = 150/Freq in Mhz . .  Value in Mtrs

 

 b) Corrected length          = Half wave length x 0.955

 

 And this correction needs to be done for Transmitting antenna at the final location! for the best SWR!

Inputs/corrections from other hams are more than welcome.

Enjoy Amateur Radio.

73  

SWL Tushar Gupta