Reconfigurable Ultra-Wideband Antenna Array Kit – part 2 (Spacing)

Why Spacing Matters

Firstly, the antenna array I am designing is a fixed in-phase array. Hence we assume that the total path length from each antenna to the single input/output connection are the same length. This makes the design and analysis much simpler, especially for an ultra-wide-band design.

In my design signals that arrive at right angle to the antenna will add up co-herently (in-phase)

spacing boresight

Signals arriving from boresight add up in phase

Read more ›

Posted in Uncategorized

Ultra-Wideband Antenna Lab Measurements


Antenna being tested in anechoic chamber

My Vivaldi Antenna was recently tested by Antenna Test Lab who offer an excellent professional antenna testing facility. Antenna Test Lab are able to provide customers with full 2D/3D antenna measurement using their anechoic antenna testing chamber. Read more ›

Tagged with: , , ,
Posted in Antennas

UWB Antenna R&D Survey

I am conducting a quick survey to help discover what developments people would most like to take my UWB antenna forward. I would be really grateful if you could take a few minutes to have your say.

Posted in Uncategorized

Reconfigurable Ultra-Wideband Antenna Array Kit – part 1

My next project after successfully building my Ultra-Wideband Vivaldi antenna is to use it to create a UWB antenna array. I will assume that most readers are at least slightly familiar with the concept of an array, I will give a quick introduction, but for those that want some background reading here is a good site to look at.

In essence we create when we sum the output of multiple antennas to increase the gain and directivity. Of key importance when we do this is to control the phase of the incoming signal that we are adding. I will be building one of the simplest forms of array, where all antennas are summed with an equal phase offset. This will have the effect of increasing the gain on the antenna boresight (and reducing the gain at other angles (I will get to grating lobes in another post)).

array basic

All antennas fed with equal phase offset.

The simplest way to do this is with a ‘corporate’ feed that consists solely of 2 way Read more ›

Tagged with: , , ,
Posted in Uncategorized

Making an Ultra-Wideband Antenna – Part 3 (performance)

Update – this antenna was professionally measured at AntennaTetLab results here

Follow this link to see more info on the original creation of the Palm Tree Vivaldi Antenna developed by Dr. Alexandre at the Laboratory Maxwell in Brazil.

Final Antenna (The Palm Tree Vivaldi Antenna)

Final Antenna

Here is the final antenna. I am still waiting on some SMA connectors for the 1mm PCB. For now I have bodged a 1.6mm SMA connector onto one of the boards for testing.

Antenna with temporary 1.6mm SMA

The antenna measures about 90mm x150mm x 1mm so is extremely portable.

S11/Return Loss/SWR

Return loss or SWR(Standing Wave Ratio) is a measure of how much of the power that you send to an antenna is reflected back to the input port. This may also be called an S11 measurement. Return loss and SWR are basically 2 ways of representing the same thing and it is fairly easy to convert between measurements if required. SWR is given as a ratio while Return Loss is normally(but not universally) quoted in decibels.

Read more ›

Tagged with: , , ,
Posted in Antennas

Making an Ultra-Wideband Antenna – Part 2 (Introducing the Palm Tree Vivaldi Antenna)

The Vivaldi Antenna

My chosen antenna design is a version of the Vivaldi antenna. The Vivaldi was named by fellow Brit Peter Gibson. It is believed that the name came out of Gibson’s love of classical music, and in may ways the Vivaldi antenna resembles the horn of a brass instrument.

Basic Vivaldi Antenna

Why choose this antenna? Well primarily it can be manufactures cheaply with conventional printed circuit technology. This allows me to have it built to a high level of quality and repeatability. Secondly the antenna is capable of incredible bandwidths and also has a reasonable level of gain. In fact, I don’t think there is another antenna in this form factor that can provide more gain over a similar bandwidth.

Read more ›

Tagged with: , , ,
Posted in Antennas

Making an Ultra-wideband Antenna – Part 1 (UWB Antenna Options)

Having backed the new LimeSDR mini crowdsupply campaign, I am expecting delivery of a highly capable software radio with the ability to receive and transmit at frequencies up to 3.8GHz. This is brilliant and the small size means that it can always be in my bag as and when I need to investigate some RF signals. But what antenna do I use?

Most people would settle for a mag-mount monopole, but these are inherently narrow band and while you can telescopically adjust the length it is pain and hard to get the frequency spot on. Also as an omni-directional antenna its not much good for hunting unknown signals.

What I wanted was a small very wide-band antenna with plenty of gain. The solution is the Ultra Wide Band(UWB) antenna. In this series of posts I will discuss some of the candidate antennas, detail why I selected the one I did, discuss the chosen design, introduce some of the tweaks to improve performance, and provide some measured results.

Read more ›

Tagged with: , ,
Posted in Antennas