We are presenting our new antenna for the 4m / 70MHz band: Xurelo-4.

There is not a lot of people into the 4m band, mainly because of it not being allocated for Amateur Radio use in several contruies. For this reason, there is some lack of resources on the internet when it comes to homebrewing your own antennae, filters , amplifiers or transverters for this specific band. In an attempt to solve this, we would like to offer an antenna characterised by its simple design, cheap cost and facility to build, with the aim of encouraging new hams to get into this lovely band.

Main features

Xurelo-4 is a light antenna that can be used to operate the 4m band portable. Here are its main features:

• Removable elements: in order to allow its use in portable situations, all of the elements are made out of 1m long threaded rods, so that they can fit inside even the smallest of the cars

• Adapt it to your needs: while the following guide focus on an specific setup, this antenna can be built with tubes or rods of different diamenters, depending on whether you plan to use it for working portable or from home

• Cheap and easy to build: all the materials involved are easy to find in any hardware store. The plans of the 3D printed parts are also public so that anyone can print them at home.

• Optimised spects for Amatur Radio: Xurelo-4 is able to ofer good gain, Side Lobes Level and SWR across the whole 4m band

• Choose any boom: Xurelo-6 has been design to be assembled with any boom, independently on whether it uses a non-conductive (fiberglass, PVC…) or conductive (aluminum, titanum, carbon fiber…) material.

Antenna Specifications

70MHz / 4m

Note: bandwidth is measured between points at 1.5 SWR (very conesrvative measure). XPD is referred to broadside direction

Simulated radiation pattern	Simulated SWR

Bill of materials

* This antenna can be build by using elements of diameters ranging from 4mm to 16mm. In order to build the detachable version shwon in this post, M6 threaded rods are recommended, since they offer a good balance between flex and weight. You can also use full-length aluminuum or carbon fiber tubes if you are looking for a more consistent setup or for a non-portable version.

** Thanks to the 3D printed parts, the elements will be isolated from the boom. Hence, both conductive (aluminum, titanium, carbon fiber…) and non-conductive (fiberglass, PVC…) materials can be used.

*** 3D printable parts below are designed for M6 rods and round boom of 16mm of diammeter. They are easily editable for other setups.

Assembly instructions

Work in progress! (I need time and budget :) )

Usage

The portable version of Xurelo-4 (described above) uses M6 threaded rods for the elements. This, together with the use of the threaded sleeves, ensures that there is a good electrical connection between the different rods that make up an element while offering an easy way to disassemble the antenna and pack it home. There is no excuses to take this in your car and start working this new band!

With respect to its height, it is recommended to place it at least 1,75m above ground in case of working in a location with relatively-high soil conductivity.

Finally, recall that this antenna was not designed to be used in a fixed emplacement for extended periods of time. If you want to use it for this purpose, the length and spaceing of the different elements can be useful, but you will need to perform some modifications to the structure of the antenna in order to increase its mechanical consistency.