Radio Technical

RF Energy Exposure

Are you concerned that your Wi-Fi router is causing cancer? Worried that your smart electric meter is giving you headaches? There is a lot of pseudoscience, crazy theories, and false information out there when it comes to the effects of RF energy emissions. There are hundreds and hundreds of websites out there which use human […]

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The main RFSim99 display, showing a multi-pole low pass filter.

Free RF simulation software

I’ve been using RF sim 99 (aka RFSim99) for over a decade, and it’s proved invaluable again and again during that time, and continues to do so. RFSim99 is a freeware RF simulation software utility. It’s small, fast, and reliable. I should make it clear that it performs basic RF simulation only, and is nothing like Genesys/ADS, […]

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Handheld Power Obsession

Or, also known as “linear units in a logarithmic world”. Among the cheap handheld radio community, especially after the release of the Baofeng BF-F8HP, there seems to be this huge obsession with RF transmit power. Yes, the BF-F8HP is rated at 8 Watts on its maximum setting, but what do you really get for that […]

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2-FSK

Frequency Shift Keying (FSK)

Almost everyone has heard of FM, but not everyone has heard of FSK. Frequency Shift Keying is a modulation scheme which utilizes changes in the frequency of the carrier wave to communicate data. For example, you can see the change in frequency in the image to the right. The lower frequency may indicate a “1” […]

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Why 50 ohms?

Coaxial cables, antennas, amplifier inputs and outputs, typically have either a 50 ohm or 75 ohm characteristic impedance. Why? It all comes down to the characteristic impedance value for maximum power transfer being 30 ohms, while the characteristic impedance for theoretical minimum attenuation (loss) is 77.5 ohms. 50 ohms is more or less in the […]

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Baofeng UV-5R+ Harmonics

It seems that the ARRL and a number of individuals have been taking a serious look at harmonics and other spurious emissions from various ham transceivers, including the ubiquitous Baofeng range of handheld transceivers. So, a while ago, I decided to take my Baofeng UV-5R+ to work and see what mine looked like. I don’t […]

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Antenna Field Regions

Antenna radiation is made up of several different regions. The transitions between these regions are not distinct and changes between them are gradual. The reactive near-field region is the region close to the antenna. In the reactive near-field region, the energy decays very rapidly with distance. The electric fields do not exist alone by themselves […]

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