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Monday, August 16, 2010

Vertical Dipole Antenna
For Amateur Radio
VHF 2Mtr (144.000 to 146.000)
Construct your Vertical Dipole

Requirements :-

1) Copper or Aluminum Tube or solid Rod Or Telescopic Wipes
2) Mast PVC

        Hi friend I have homebrewed one vertical dipole for myself &Would like to share it with everyone , This project is very Cheap and easy to home brew with excellent result, I have make Use of telescopic wipes supplied along with Television set .Also These wipes are available in the market.

     Dipole is an antenna that can be made by a simple wire, with a center-fed driven element for transmitting or receiving radio frequency. These antennas are the simplest practical antennas.
The dipole can be mounted horizontal but then the Radiation Pattern will be Directional.

If the radials are North South then the Radiation pattern will be East West .
Vertically mounted Antenna will radiate in Omni direction.

This is my vertical Dipole have installed at my QTH for 2 Mtr
As both the radials are in a vertical Position , so it’s radiating Omni directional , currently using with my ICOM F-310(25watt), Mast is 1” PVC pipe , Feed line I have used is LMR 400 to my Rig , (very low loss cable ) Even with QRP 100 Mille watts its possible to trigger MATHERAN Repeater distance is approx. 50 KM & MUMBAI repeater 23 KM away from My QTH in Vile Parle,

To calculate the length of the wipes the formula is

Length of the Wipe = 468 / FRQ In Mhz
Length of the Wipe = 468 / 145.000
Total Length of the Wipe = 3.22 Feet
Length of one arm is 3.22 / 2 = 1.6137 Feet or 19.32 Inches
I have used Telescope wipes as it is easy to tune the antenna, Once you perfectly tune the antenna , you even can use aluminum or copper tube of the same length for the radials,

 The SWR reading on 144.000 Mhz 1:1.2 (20 watt)

The SWR reading on 145.000 Mhz 1:1 (20 Watt)

The SWR reading on 146.000 Mhz 1:1 (20 Watt)

I am very much thankful to Team MARI  to give me this wonderful idea & support in this project,


DE JAYESH (…- ..- ..--- .. …- …-)

Monday, July 26, 2010

Easy Eggbeater Antenna
For Amateur Radio to work with Satellite
Requirements :-
1) Copper or Aluminum Tube or solid Rod (4 to 5mm)
2) Cable RG 58 ( 50 OHMS)
3) Mast PVC
4) PVC Base
5) Nut, bolt etc.
          Eggbeater Antenna consist of two Loops , Both the loops are connected to each other with RG 58,(50 ohms) it should be quarter wave length , Solder outer shield at both the end and the center conductor connects to the loops as shown in the Fig.1 . The impedance of the phasing line is 100 ohms. So point 1, 2 and point 3, 4 is 50 ohms

Circumference for Each Loop Should be 215.28 CM For VHF
Phasing Line should be 34.15 CM For VHF

Circumference for Each Loop should be 75.90 CM For UHF
Phasing Line should be 11.38 CM For UHF

          For better understanding The above Fig.1 show the loops are separated , Both the loops are full wave mounted at right angle to each other and coupled together and one inside another, Fig 4 shows about mounting these loops This antenna is omni directional circularly polarized.,( FIG 2) this design is good for Low Earth orbiting Satellites also by adding the reflectors “GAIN” can be improved , At point “X” a nylon washer or any isolator is to be use, Both the loops should not be touching each other

           To match the unbalanced source(RG 58) to a balance load (antenna )We will use BALUN that will be 4:1, This BALUN will give an impedance step up ratio of 4:1 as the impedance of the feeder is 50 ohms it will provide a match for 200 ohms terminating impedance, also to convert the high output Impedance of the BALUN(200 ohms) to 50 ohms impedance of the antenna balanced line that is QSECTION must be added to it Refer to FIG 3
Length of the Q section should be 34.15 CM for VHF
Length of the BALUN 4:1 should be 68.20 CM for VHF

Length of the Q section should be 11.38 CM for UHF
Length of the BALUN 4:1 should be 22.76 CM for UHF
Eggbeater Antenna View From Top

Have try to simplified the idea OF 0n6wg/f5vif (thanks for everything ) for better understanding ,
DE JAYESH (…- ..- ..--- .. …- …-)