MF/LF OPERATING: Life Below the AM Broadcast Band
As I prepare this column in early spring, we are 18 months into activity on the 630- and 2200-meter bands regulated under FCC Part 97 rules and, out of the scores of questions that I receive between each article, only two have ever been on the subject of how to take measurements that lead to determination of Effective Isotropic Radiated Power, or EIRP. That potentially means a couple of things:
1) Most people “get it” and the procedures are straightforward. Procedure-driven individuals will generally find this to be the case; or
2) Amateurs are rolling the dice using best-guess tactics and don’t have a clue what is actually being radiated from their antennas.
The truth probably lies somewhere between the two.
A Nebulous Undertaking
It’s true that determining accurate EIRP values for a suburban backyard antenna for use below the AM broadcast band can be a nebulous undertaking in which even the most careful measurements might result in errors as high as three to six decibels. Even so, I’ve been careful to stress that amateurs should exercise due diligence in determining their station parameters and in getting that information, and how they arrived at their values, on paper. While I don’t expect anyone to show up on most amateurs’ doorsteps, scrutinizing their operation, it’s important for us to show that we
