Dipole Antenna

I have a radio transmitter and i need to make a dipole antenna for it. Here are some questions you need to answer. How do i connect it to the RG/58 coax cable? how long does each side need to be for the frequency of 91.3MHz? (im putting out 1 Watt) what kind of wire should i use, what should the gauge be? what do i mount it in PVC pipe? It would be helpful for all the information you can give me. Thanks

Dipole length is one half wave length (minus a little to allow for 'end effect").

Full wavelength on 91.3 MHz is 3.284 metres, so you need half that or 1.642 metres.

Antenna can be either vertical OR horizontal. A dipole generally is feed in the centre. It needs an insulator there which allows you to do the terminations. You will also need insulators at each end. The coax needs to be supported by wrapping around the centre insulator. There are special insulators sold for this purpose. Height should be as high as you can manage but should not be less than one wavelength (below the height, ground effects influence the antenna performance).

The gauge is immaterial. Since it needs to support some weight from the insulators, coaxial feeder and supporting ropes, best to use something between 12G and 18G. It can be insulated wire (or not). The insulation provides some protection for the wire so will usually last longer. Usually copper or aluminum. Steel will rust.

Coaxial can be terminated directly to the wire (centre to one side, shield to the other). Ideally, a balun is useful to reduce out of balance currents in the outer shield of the co-ax but is not vital.

I doubt there is any benefit to mounting in PVC pipe and may even have some detriment. PVC is not a good dielectric at high frequencies.

2009-06-14 23:24:02 by Jordan

www.antenna-theory.com presents the analysis of the dipole antenna! The short dipole is discussed first, followed by the half-wave dipole antenna ...

i need the hardware requirements and it will be good if i could get the price for each hardware.

Check out any Ham Radio site.
Before you can design an antenna, you need to know what frequency it needs to be tuned to.
Basically a halfwave dipole is a wire or metal rod with a feed cable connected to the centre.
The length is half the wave length of the frequency required.

2007-09-08 03:57:40 by faarighbanda

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the model should give a detailed explanation on how to go thru with the project.preferable in .pdf format.

You need to specify the desired gain (directionality) before you can get much help. There are too many possible solutions.

2007-09-08 04:02:38 by faarighbanda

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Half wavelength? Quarter wavelength?
What about materials?
Coax cable? (50 Ohm or 75 Ohm?)

Any good websites that explain all this?

TV channels are broadcast on a very wide range of frequencies from about 54Mhz through 600Mhz and beyond. Accordingly the range of wavelenghts invovled is also quite large. While you can design a dipole to be resonant for one channel, it will be all off for the next. Thats why the old style roof antennas are arrow shaped. They are of an antenna class called Log periodic arrays. These antennas are resonant at a lot of frequencies and also have gain certain directions.

Try one of these books:

http://www.arrl.org/catalog/index.php3?c ategory=Antennas%2C+Transmission+Lines+a nd+Propagation

You can probably borrow at least some of them from your local library or library system.

2009-05-06 18:20:48 by core2extreme

Which television channel would require the smallest length of dipole antenna? A. ch 2
B. ch 12
C. Ch 30
D. ch 83

please explain
thank u for ur response. i am not trying to get anyone to do the work for me. i asked for an explanation so i would understand concepts. thanks

The highest one. The antenna is a fraction of the wavelength, so the highest frequency, which has the shortest wavelength, will have the shortest antenna.

2006-10-14 08:31:53 by Diggler AKA The Cab Driver