Pardon the possible simplicity of this question but I am incredibly new to antenna design. So, I settled on a simple loop antenna, made of 14awg copper and about 18inches circumference (tuned to 644Mhz) hooked to a Balun. I picked that size because that is the weakest channel I wish to receive. The antenna picks up a pile of other channels just fine but still gets no viable signal on that channel. I know that I cant just go about making things larger arbitrarily so how do I increase gain? Can I somehow add other loops (I think I saw a picture of this) and if so how do I chain these together?
N.B. I am height limited and this is stuck inside so the old advice of put it higher and remove obstructions is difficult.