ARRL Ham Bands Chart - 2017
A chart of all U.S. authorized amateur radio bands.

Atomic Time Clock - NIST
Official U.S. government time.

Coaxial Cable and Ladder Line A description of coaxial cable, ladder line and their connectors, including attenuation tables.

Conductor Properties
A table of properties of copper wire conductors.

Constants & Formulas.
Several sections with constants and formulas that may be of interest to Hams

Decibels
A description of the decibel and how it is used.

Electromagnetic Spectrum Chart
The spectrum chart seen at right.

ITU Recommendations of Interest
Numerous documents from the ITU on various topics, such as usage of the metric system, radiocommunication vocabulary,
use of the decibel and the neper in telecommunications, and others. See also our Regulations page for more information.

ITU Regions Map
A general map of the world showing the 3 ITU regions.

Maxwell's Equations with Text
A slide from a Pacificon presentation giving brief explanations of the 4 Maxwell equations.

Narrow Band Emergency Messaging System (NBEMS)
A short description and several references for software that allows sending digital data over almost any radio.

Noise Cancelers - RFI Survival Guide
Helping hams and shortwave listeners lower their local HF noise floor and improve reception.

NTIA - Frequency Allocation Chart - 2011
A chart of all U.S. frequency allocations by the FCC and NTIA, as of 2011, as shown below.

Peak Envelope Power
An explanation of Peak Envelope Power (PEP) and how to calculate it.

Periodic Table of the Elements
A chart of the periodic table, customized with some annotations, including all elements discovered through 2011.

Schematic Symbols
A table of common schematic symbols used in circuit diagrams. From the ARRL.

Skin Effect.
A description of the skin effect in conductors, along with a table of depths for the skin effect at various frequencies.