2m J-Pole Antenna:
It was a coincidence when I came to the homepage of
KA1FSB and saw his
construction of a J-Pole antenna for the 2m Band. I decided to build this antenna by the
same methode however I used the input joke as dexcribed on the homepage of
Martin, DK7ZB. See my
pictures. The sizes I used are that of Martin, DK7ZB. I used a simple pastic tubing
for electrical installation. Top and bottom are covered with a plastic washer. A BNC
connector is mounted on the bottom cover.
I work already over 1 year on some projects to get QRV on 23cm with homebrewed equipment
The antenna will be a 1,4m dish which is not finished yet. The feed for this dish will be
the here described horn antenna. It is assembled out ob brass with a thickness of 0.4mm. Each side
of the horn is a single plate. The plates are soldered together. The detailed construction scheme
was published in an old DUBUS issue. This is the PDF for the 23cm/13cm
HORN ANTENNA. The antenna input SWR was
measured during a ham fest with a professional network analyser. On 1296 MHz the Return Loss is >23dB!!
For 13cm, however, the SWR is too high against the described version. Nevertheless I want to use this
horn only for 23cm so it is perfect.
T2LT (open sleeve dipole) for the 10m Band
In principle this is a vertical dipole. The construction is very easy to handle. T2LT stands for
"Tuned Transmission Line Trap" Antenna. The principle corresponds to the sleeve dipole or the coaxial dipole.
The feedpoint of this antenna is in the mid point of the dipole. The shield of the coax is used as one leg of
the dipole. This leg has to be limited by the trap which is formed in this case by a coil and a capacitor. Note
that the coil is only effective on the shield of the coax and the parallel capacitor is soldered only to the
shield. The inner coax conductor is not affected. Therefore the leg which is made up of the coax shield depends
not on the velocity factor of the coax. The coax leg has the same length as the upper wire leg. The dipole can
also be used horizontally or spanned as inverted V. You will find also some constructions for VHF or UHF in the
internet. In this frequency range the trap is made by a simple wounded lamda/4 joke. That would be also possible
to use for HF, however a trap constructed as described here has an higher Q. Find construction details of my 10m
dipole in the pictures below.
I have calculated some traps for other HF bands. So, have a look into this file:
T2LT Data for HF bands
7-Element Yagi for 70cm (DK7ZB Design)
This Yagi was built by a design of Martin, DK7ZB. It is a "ultralight version built out
of silver solder with 2mm diameter for the elements and 8mm aluminium tube for the radiator.
The assembly of the elements is shown on the pictures.
2/3-Element 2m/70cm Dualband Yagi with single feed (DK7ZB Design)
This is a great design for use with 2m/70cm transceivers with a single antenna connector. You need no diplexer.
The antenna is built again in "ultralight" design and has a fixed cable to connect directly to the transceiver as I use
it mainly for portable work without a tower. Details can be found on the DK7ZB homepage