LHS Episode #623: Dipole Tuning Listener Feedback

Show Notes

Featured Topic

• Feedback from Jonathan Rhoades KD2HBV
  • I’m trying to figure out how to tune a homebrew dipole antenna using the swr readout on my qrp rig (zBitx).  Thought if I’m interested in this, perhaps others are, and maybe it would fit into your short topic list.
• What Is a Dipole?
  • A dipole is simply a wire antenna fed at its center, with two equal-length halves extending in opposite directions. It’s a balanced antenna — symmetrical around the feedpoint. To be resonant, it needs to be a half-wavelength long at its operating frequency. The formula: length (feet) = 468 ÷ frequency (MHz). That gives you sizes ranging from about 16 feet on 10 meters all the way to 260 feet on 160 meters.
  • Resonance matters because it puts the antenna’s impedance in a range compatible with common coax feed lines — but resonance isn’t strictly required; an antenna tuner can compensate for dipoles that are longer or shorter.
• What is SWR?
  • Standing Wave Ratio (SWR)
  • When RF power travels down a feed line toward an antenna, some of it gets radiated — but if the antenna’s impedance doesn’t match the feed line’s impedance, some power bounces back toward the transmitter. That reflected wave and the forward wave interact, creating a pattern of high and low voltage/current points along the feed line called standing waves.
  • SWR is simply the ratio of the peak voltage to the minimum voltage of that standing wave pattern. A perfect match = 1:1 SWR (no reflected power). Higher ratios mean more mismatch and more reflected power.
• What is zBitx?
  • The zBitx is a highly compact, all-mode, all-band Software Defined Radio (SDR) transceiver designed for portable and QRP (low-power) amateur radio. Very compact in size, it measures 5.5 inches x 3 inches x 1.25 inches, and weighs 250 gms/9 ounces!
  • It covers the 80M to 10M bands, and runs digital modes like FT8 natively.
  • The zBitx is built by HF Signals and powered by a Raspberry Pi Zero, running open-source sBitx software that allows for future software upgrades.

Announcements & Feedback:

• Announcements:
  • Support the show!  
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  • Taking a break from recording for a few weeks!
    • Due to Bill doing that whole Boy Scout Jamboree thing, we’re going to skip recording for a few weeks.  Mark your calendars - July 19th and 26th are definitely out, and likely August 2nd.  Don’t panic… we’re still around, and Bill will tell us about his Jamboree adventures on the next episode (which will be #124 - typically our “featured topic” episode) after he gets home!  NOTE:  Bill MAY decide to record a podcast from Jamboree… only time will tell.
  • Memorial Service for Russ, K5TUX
    • There will be a memorial service held for Russ at our home in Mt. Vernon, Missouri on November 1, 2026.  Everyone is welcome!  If you’d like to join us, please send an email to info@lhspodcast.info and we’ll send you more info!
    • Facebook event page: https://lhs.fyi/mem
    • Comments, questions, etc: info@lhspodcast.info
  • Special Note for this episode:
    • Bill will be gone for the next few weeks to the Scouting National Jamboree, and they are always needing folks to interact with the kids through the K2BSA.  They will be operating HF on 40M – 10M, D-Star on REF033A, EchoLink on JOTA-365, and more as time, conditions, and staffing allowed.  SO, if you hear them on the air… please take a minute to chat with the lucky camper!  Bill has posted a great list of questions to ask the campers on the K2BSA website https://lhs.fyi/M1
• Feedback:
  • Email from Ray Franz, WB0SMZ
  • I just listened to a podcast of yours from a few years ago.  Podcast 537 for Qlog ham logging software.  I have it installed on Linux Mint and enjoy the software a lot. But I have noticed an issue with my installation.  The time shown for a qso is incorrect and I cannot find a solution.  I have a digital clock in UTC on my desktop so I can reference UTC time at any time.  What I found is this example:
    • Linux local time in the lower right corner is 05:34.
    • UTC TIME on my digital clock is 00:34.
    • Qlog time for current qso is 12:35 AM
  • Would you have any ideas for how I could get Qlog to log qsos is UTC time? Windows programs like Genlog, Dxlog and others default to UTC. Otherwise I love Qlog for general purpose logging. I installed from Software app on Linux Mint.

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