Antenna and EM modeling with MATLAB

[Adil Israr]

900mhz dipole

How can I calculate the length and radius of dipole antenna over a range of frequencies.eg:850MHz to 950MHz

 

[rrumpf]

dipole antenna radius

I think your question how to you calculate the length of a standard half-wave dipole and its wire radius for it to cover the frequency range of 850 MHz to 950 MHz. Is this correct?

Given the frequency in MHz, the length in meters is

L (meters) = 143 / f(MHz)

The radius I would have to dig a bit to find, but in general, the thicker the wire the broader the frequency response.

-tip

 

[Adil Israr]

dipole antenna frequency response

YA but If V want to cover a wide range of frequencies then what be the lenght,,and radius???i didn't understand the formula,will u explain it more clearly. If U have any document about dipole antenna design so plz share wid me.

 

[rrumpf]

simple 900mhz dipol antena

So if you want a dipole antenna to operate with a center frequency of 900 MHz, the length needs to be

L = 143/900 = 0.1589 meters

Here is a picture...

| <------------------- L -------------------> |

=============*=============
center feed

Does this make sense?

Was 'V' in your last message a typo or are you interested in a V-dipole?

-Tip

 

[Adil Israr]

850 mhz antenna length

V was we,ok.
Now how can i develop it in matlab.its radiation pattern,rasiation resistance etc.

 

[shameemkabir]

dipole radius antenna

Now how can i develop it in matlab.its radiation pattern,rasiation resistance etc.

Try to find the book "Antenna and EM modeling with MATLAB" and write your code.

However, I guess, first you need to know a little bit more about antenna theory.

 

[rrumpf]

whip antenna with blob in middle

If you search the forums, I uploaded the CD for this book to one of them.

-Tip

 

[rrumpf]

900 mhz dipole

As for pattern and other parameters, there is a great piece of software that is free. It is called 4NEC2 and it runs on Windows. It is based on the method of moments which is perhaps the most efficient way to model thin wire antennas.

-Tip

 

[Adil Israr]

calculate range of dipole antenna

Can we use dipole antenna for mobile communiation,i.e:for 900MHz and 1800MHz frequency bands?

 

[rrumpf]

calculate dipole antenna

You are asking about a dual-band antenna. For the frequencies you just mentioned, 1800MHz is a harmonic of 900MHz so the same antenna would work for both, but performance would be degraded a bit at the higher frequency.

There are simple ways to get much better performance out of a dual band dipole and it involves loading it somewhere in the middle. A simple qualitative explanation is this. If you add an inductor (RF choke) at the center of each arm of your dipole, the high frequency would be confined to the shorter dipole, but the longer wavelength would see the full dipole. In this way, each wavelength sees a perfect half wave dipole. You can this driving on the road. Hams, police, and emergency vehicles will use this technique on their UHF/VHF radio antennas. You will see long whips with "black blobs" in the middle of whip.

-Tip

 

[Adil Israr]

v dipole antenna radiation pattern

If I design two separate dipole antennas for each band,then I think performance would not be degraded. Is it right??what do you say??