I am testing a Discone antenna indoor.. Is it necessary to make the size of antenna bigger by decresing the frequency?? I currently testing discone where frequency is 1GHz.. but cannot get the radiation pattern.. Thx for help..
You are going to always have problems with antenna measurements indoors. First there is the reflections from walls and then there is the far field distance. At leas the second of these can be overcome if the frequency is high enough.
To answer to your question, yes, is necessarily to make the antenna larger for lower frequencies (actually this is valid for all the antennas).
Here you can find the dimensions: **broken link removed**
and this is the pattern that you have to get for Discone in open-space or using an anechoic chamber