W7YV Ham Radio

This post relates to antenna analyzers useful to amateur radio operators. I will list my experiences with these in this article. Array Solutions AIM 4170 Link:  https://www.arraysolutions.com/Products/AIM4170.htm I don't recall what I paid for my AIM 4170. It is an older version and has been replaced with the AIM 4300 ($519). The AIM 4170 exceeded my expectations. It is well worth the price if you are doing any kind of antenna work or network characterization.  The software runs under Windows 7 and works very well. I have not tried to port it to Ubuntu. The following plot is from a balun I build back in '07. This plot is from an antenna feed balun I built. Here is a photo:

In a recent conversation about the need for a balun on a dipole fed with coax, the comment was made that no balun is needed because the dipole radiates in a balanced manner. Well, maybe... If a dipole is positioned above uniform ground and there are no trees, hills, fences, buildings, or powerline poles, then the statement above might be. However, the real world has trees, has hills, fences, wet and uneven ground, and powerline poles. It would be rare to have one side of a dipole driving the same free-space radiation impedance as the other side. If there is an unbalance, then the outer shield of the coax will radiate RF to make up the difference. An easy way to think of it is to imagine that one side of the dipole radiates 10 amps of RF and the other side radiates 9 amps due to the imbalance. The difference of 1 amp has to get made up. It gets radiated from the outside of the shield of the coax. Stated differently, the coax center conductor carries 10 amps. The inner shield carri...