23cm PC Board Yagi

I wanted a bit more “oomph” from my 1W 1.2 GHz HT, so I purchased a PC board Yagi to get another 6 dB.

I have a Yaesu FT-911 1.2 GHz HT. It is a 1990’s rig gifted me by the wife of a Silent Key at my work. It is a sweet handheld, but with limited power.

WA5VJB makes a variety of PC board antennas. The 1.2 GHz 3-element Yagi is $6, which was hard to resist. He also makes other nice microwave antennas: log-periodics, patch arrays, wheels, vivaldis, etc.

I went to HSC Electronic Supply and picked up a PC mount BNC and a right-angle BNC by navigating this aisle.

23cm yagi 2

I found a short, stiff BNC cable from this bin.

23cm yagi 3

I soldered on the BNC chassis connector and epoxied it to the antenna. The PC board is beat up because I’ve been carrying it around in my backpack for ARRL Field Day. It was pristine when I got it. Nice design, the feedline attaches at the edge of the board, then there is a stripline to the driven element. The reflector element is on the back side of the board. You can just barely see it in this photo. The shield of the coax attaches to a thru-hole pad that goes to the stripline on the other side of the board. That is hidden by the connector in this photo.

23cm yagi 1

And now I have a 1.2 GHz “flamethrower” HT.

23cm yagi 4

I need to find something to stiffen that bit of coax so I don’t have to use my hand to stabilize it. Other that than, pretty sweet.

6 thoughts on “23cm PC Board Yagi

  1. SOTA introduced a Microwave Award for activators in July 2014. For contacts at 23 cm and above, you can get awards based on the cumulative distance. The first award is at 50 km, so that might take a while to earn. You need to log the location of the chaser. The summit location is already known, of course. http://reflector.sota.org.uk/t/sota-microwave-award/8995

    The UK Microwave Group offers a bunch of awards, but those are for British amateurs. http://www.microwavers.org/awards.htm

    In the US, the ARRL VHF Contests are a handy way to find activity up there.

    Otherwise, a contact on 23 cm is just another SOTA contact.

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  2. I would have soldered the coax directly to the board, and avoided using the extra connectors.

    For stiffening, how about some fiberglass rod or tube from Tap Plastics. There’s one in MV (Castro), two in SJ (The Alameda, near Julian, and Blossom hill, near Eastridge), and one in Fremont (Mowry, across from OSH).

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  3. I have a question that needs to be answered if anyone can help me understand.

    I’ve been dealing with different antennas for years but this is my first PCB logic periodic antenna.

    Now this is what has me confused.

    On the front end of this antenna is a way to connect a SMA connector to the antenna.

    There are five holes in the antenna ready to accept an SMA female connector soldered to it.

    I don’t see a problem there.

    But what I can’t seem to get my head wrapped around, is the fact that everything is grounded out.

    In other words all five holes in the antenna that is ready to accept the SMA connector seem to be connected to each other.

    if all five holes are connected to each other then where is the lead that means that they’ll all be grounded out when I connect the SMA connector.

    Even though the center of the SMA connector has a lead connection for the center it is still grounded to the other 4.

    When I connect a volt ohm meter and run a continuity tester to each one of these connections on the tip of the antenna they all seem to be connected.

    so it would seem to me if I hook a coaxial cable to this antenna the way it is set up it will automatically be grounded out .

    I don’t understand how this would work.

    Can someone straighten me out on this?

    Am I missing something?

    Any help will do I thank you in advance

    Larry

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    • Hi Larry, When you check with a continuity tester you are confirming a DC connection. RF behaves very differently and there will be capacitance between the shield and the centre conductor. So, providing you do not short the shield and the centre conductor at the feed point all will be well.

      73’s Ian, VK2YG

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