Designing an Ultra Wideband Vivaldi Antenna

The LimeSDR mini is able to receive over a huge frequency range (10 MHz - 3.5 GHz), so having recently bought one "hexandflex" wanted to build an ultra wideband antenna to go along with it. On his three part blog post hexandflex introduces us to various ultra wideband antennas, introduces us to and shows us how to design and build a Vivaldi ultra wideband antenna, and measures the performance of the Vivaldi that he built.

The Vivaldi is a fairly well known ultra wideband antenna that is directional. It is fairly easy to build out of a PCB board, but requires some careful design considerations to work well. In the second post hexandflex goes over all the design considerations that he put into his Vivaldi incliding the feed design, substrate choice and additional improvements like adding corrugations and crafting the geometry for a lens effect.

The results show that the antenna works well as a directional antenna above 1.7 GHz, and begins to work more like a standard dipole below 1.7 GHz. Directional gain is greater than 5dB above 1.7 GHz, and becomes negative below 1 GHz. Although hexandflex notes that the gain below 1 GHz is still reasonable, and probably still better than any untuned monopole.

Hexandflex has put up a small number of Vivaldi antennas that he's produced up for sale on Tindie for US$18. Currently he has a limited batch of units to sell, but notes that he may run additional batches if they are popular.

Hexandflex's Vivaldi Antenna
Hexandflex's Vivaldi Antenna

7 comments

  1. HexAndFlex

    Kent, i will have to try one of your Vivaldi’s. They do look good. Im also intersted in your UWB omni antenna. That looks really useful too.

    The RFspace vivaldis look really good too, a lot more expensive, but they have some really big metal versions that go all the way down to about 450MHz.

  2. Drone

    Sorry, I forgot the disclosure in my comment: I’m not affiliated with Kent Electronics in any way; not even as a Customer (yet).

  3. Drone

    Kudos to “HexAndFlex” for some nice work on this Vivaldi PCB antenna. This is a welcome addition to the few examples of true UWB PCB microwave antennas available for affordable prices.

    As an alternative, take a look at the affordable PCB antennas of various types by Kent Electronics (WA5VJB) in Texas. Amongst the myriad antennas he sells are a line of UWB antennas, including Vivaldi designs, although the Vivaldi antennas on the Kent Electronics site at first glance appear a bit less sophisticated than the example from HexAndFlex. See here:

    http://www.wa5vjb.com/

    The Kent Antennas price list is linked below. A $13 USD 1.5-15 GHz Vivaldi antenna is listed which is similar to the HexAndFlex design in frequency range, but unfortunately, I could not easily find a data sheet for that particular antenna. Also, it seems the price does not include the connector (but I’m not sure about this). See the Kent Electronics price list here:

    http://www.wa5vjb.com/prices.html

    Also from the Kent Electronics Web site I see this: “Kent Electronics has over 1000 custom designed Printed Circuit Board Antennas in its library. Custom Design and Testing Services are available.” Good to know 🙂

    Have Fun…

  4. HexAndFlex

    @RTLSDR Thanks for featuring this. I woke up yesterday morning with a surprise flood of orders for this antenna. It was a manic evening of soldering and packing, but most people got there antennas posted out today. Hopefully everyone who saw this article and decided to purchase one will find it useful. I’m nearly out of stock now, but have some more parts on order with a lead time of about 2 weeks. If anyone is interested ,but missed out due to this rush, you can add yourself to a Tindie waiting list to be notified.

    My next plan is to create a UWB Power Divider kit to give owners a really easy way to experiment with antenna arrays. I will start to write up the design for this soon.

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