antenna-theory.com

[Cristopher.Van.Paul]

I am told to do a project with NEC SW software, but I do not know how to give it a start. I would be glad if someone gave me a clue how to start. The description of the project is:

Design dual band resonant quadrifilar helix GPS antenna that will operate at 1.227 GHz and 1.575 GHz frequencies. The GPS satellite transmit power level is 50 W. The GPS receivers can track the location for signal levels as low as -156 dBm. The antenna will be connected to 50 ohms RF system. Present results in printed and 3D/2D graphic format. Include efficency calculations. Use standard AWGN wire thicknesses in your design. Comment on implementation.

[bigSteve]

This sounds like a stupid homework problem

[Cristopher.Van.Paul]

I guess it is a better idea to help rather than saying it is stupid!

[admin]

you guessed wrong

do your own homework or there is no point in getting an education

[helix]

I would suggest using Feko LITE rather than NEC. Feko LITE is a very similar code (both are thin-wire MoM codes) and can be downloaded and used for free. By using Feko LITE you will save hours by avoiding text-based input and output.

The bit about GPS satellite transmitting 50W is strange information, and it is also not correct. The receiver sensitivity number is also a bit off, what probably matters most is acquisition sensitivity (which is a lot higher than tracking sensitivity). But maybe they want you to figure out the required gain. You will need to know an approximate GPS satellite range (and the Friis equation) to calculate the required receive gain.

Stutzman and Thiele covers helix antennas, I suggest learning that chapter/section and starting with a design based on their formulas and see how it performs in the code.