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Boomer Yagi

My Technical Notebook
A VHF folded dipole construction Coaxial cable Velocity test Stacking Colinear 3 x 3/4 This Page Transmission lines problems Television Receiver Only

This antenna was imitated from the original Boomer Yagi type 214 FB
all the parts size and layout was arrange as close as posible to the original
except the materials type for the director elements and reflector.
Parts used
  1 aluminum square boom 1¼ x 1¼ inch x 4.5 m
  1 aluminum square boom 1½ x 1½ inch x 2.5 m
13 pcs 4 mm Ø brass welding rods
  7 pcs 4 mm element brackets 1½ x 1 ½
  6 pcs 4 mm element brackets 1¼ x 1 ¼
   1 pc Ø ¼ inch 94,5 cm Al tube
 1 Tmatch assembly unit  1 reflector brackets
 1 mast bracket with 4 U bolts
 1 baloon coaxial cable 79.5 cm 8214 VW-1

10 September 1980.-




Phisical construction

elementlength in cm
r1 r2
r3
de
d1
d2
d3
d4
d5
d6
d7
d8
d9
d10
96.52
100.33
94.60
92,66
91.44
90.17
88.90
87.50
87.50
87.50
87.50
87.50
88.90

Reflector

Feed point

 

Boom

To provide rigidity, the boom was constructed using double aluminum square profile, a full length of 1¼ x 1¼ inch aluminum profile was inserted into a 1½ x 1½ inch aluminum profile where d1 through d7 will be placed, and fastened together with rivits.

Untuk memperoleh boom yang kokoh digunakan profil segi 4 aluminium ganda, sebuah profil 1¼ x 1¼ inci sepanjang antena dimasukan kedalam profil 1½ x 1½ inci sepanjang 2,5 meter tempat d1 sampai d7 berada. dan di keling satu dengan yang lain.

distance between elements in cm
r1/r2
r3
de
d1
d2
d3
d4
d5
d6
d7
d8
d9
10.6
27.90
41
41
41
41
41
41
41
41
41
41
r3
de
d1
d2
d3
d4
d5
d6
d7
d8
d9
d10

Driven element (radiator)
T matching unit

Description

Previousely I made the antenna using 1 inch Ø aluminum tube for the antenna boom and all the elements were hold and fastened into the boom with a self made aluminum clamps and self tapping screws. The reflector boom was clamped together to the rear part of the main boom with a pair of triangle shaped 1mm aluminum sheet. The matching unit was made also from a piece of 1 mm aluminum sheet and fastened to the boom with a shelf tapping screw. The electrical performance was likewise the same as the above construction. But since the construction was not rigid enough because of the material used was too thin. It caused the boom bend down when installed to the antenna mast. After that I decided to use a more rigid material, and while looking around for the materials at the local hardware market called Pasar Kenari, I found in one of the store sells local made antena brackets and squared aluminum profile for the boom that is more rigid. And so the above cunstruction was design using those material.

Sebelumnya saya membuat antena ini menggunakan pipa aluninium 1 inci dan semua element saya pasang di boom mengunakan self tapping screws dan clamp kecil buatan sendiri dari lempeng aluminium setebal 1mm. Bagian reflektornya saya jepit dibagian belakang boom dengan sepasang lempeng segitiga terbuat dari lempeng aluminium setebal 1mm. Demikian juga bagian T macthing unitnya saya buat dari selembar lempeng aluminium setebal 1 mm dan dipasang di boom menggunakan self tapping screw. Hasilnya memang hampir sama dengan diatas namun konstruksinya kurang kuat karena digunakannya bahan yang terlalu tipis, menyebabkan boomnya melengkung kebawah ketika dipasang di tiang antenna. Kemudian saya putuskan untuk memakai bahan yang lebih kuat. Ketika untuk itu saya mencari bahan di Pasar Kenari, ada sebuah kios yang menjual bracket antena buatan lokal dan juga profil aluminium berbentuk segi empat yang lebih kokoh. Dengan demikian kontstruksi diatas dibuat menggunakan bahan tersebut.

Test result

TM
in cm
VSWR at VHF frequency
144.5145145.5146146.5147147.5148
18.81.61.351.21.121.121.121.121.2
191.551.351.21.11.11.11.151.2

As seen from the test chart the center frequency is around 146.5 mHz
Seperti terlihat di daftar percobaan frekwensi tengahnya adalah 146.5 mHz


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Updated February 2000.-