# Need Help in simulation of VLF loop antenna on MULTISIM....Urgent Plz....

Discussion in 'Wireless & RF Design' started by farairo, Jun 5, 2009.

1. ### farairo Thread Starter New Member

Jun 5, 2009
5
0
Hi i am new on this forum so i dont know much abt this forum but i need help with multisim... i need to simulate very low frequency loop antenna on multisim and for that i need to define voltage source,capactance,inductance and resistance of wire on parameters like number of turns,Area of wire,frequency etc but couldn't find any way to define these paramters.Can anybody help me with this i would be very thankful....

2. ### ELECTRONERD AAC Fanatic!

May 26, 2009
1,146
16
Hello!

Loop antennas are one of the simplest forms of antennas out there. To figure out the required capacitance values and inductor values you will need to look at this formula:

Fr= 1/2(pi)(Sqre of L)(Sqre of C) where Fr is your resonant frequency, sqre of L is the square root of your inductor value and so forth. Remember to take each value down! So for example if we have a 100uH inductor that is the same as 0.0001F. This equation is also helpful for oscillators like hartley or copritts oscillators!

Now the higher you go in frequency, the shorter the wave gets, and also the shorter your antenna will have to be! So with VLF, you will have a fairly long loop antenna. The inductor and capacitor values will compensate for the loss of length. Although it is theoretically long "electrically," "physically" it isn't.

I would also suggest that you get an antenna analyzer (or borrow one), these are very helpful. There will be a SWR meter, and an impedance meter. SWR is stands for Standing Wave Ratio. So if you put a number of watts into an antenna (forward power) you dont want to get a lot of power back (reflected power). So you want the lowest SWR you can get. Those inductors and capacitors will help reduce your SWR.

Now I also suggest that you use coax to feed it to your source, this will reduce loss over distances rather than conventional wire. Make sure you know what impedance to get, usually it is 50Ω or 75Ω coax.

Good Luck and have fun!

3. ### farairo Thread Starter New Member

Jun 5, 2009
5
0

Hi thanks for ur advice buddy but actually my problem is different.I know lot about loop anteena and i m doing this project for universitry so they r providing me all the equipments. My problem is i want to create new components like inductance which have user defined parameters like number of turns ,area of the wire, frequency instead of using virtual inductance in MULTISIM.same for capatance and voltage source and resistance but i dont know how to do it on multisim as i hv never used it before there is option of creating new components but i dont know how to define parameters in it....

4. ### ELECTRONERD AAC Fanatic!

May 26, 2009
1,146
16
Hello,

I would suggest that you go to http://www.qrz.com/ and post there. They are a bunch of amateur radio geeks and I'm sure you'll find your answer.