I received a ‘freebie’ Diamond X-30 2m 70cm Base Station omnidirectional vertical antenna from a local ham. This is Part 1 of my evaluation of this antenna where I check Return Loss on both bands.
Part 2 will follow when I get some time to set up a field test for looking at the actual gain over a reference dipole when it is mounted on the top of a mast as well its pattern at 2m and 70cm when it is when mounted on the side of a mast (or tower leg) at various spacings. Whether we use a dipole array or a collinear antenna, a side mounted antenna will have a pattern that will be affected by the spacing between the antenna and tower leg or mast upon which it is mounted.
Video Rating: 5 / 5
Here is a easy to make dual-band vertical antenna, It covers the 2 mtrs and 70 cm band, As it is it could be suspended by String in the loft or slid inside a lenght of plastic tube to be used outside. Any questions drop me a message.
Video Rating: 4 / 5
The design is not my own, Its for ANYONE to copy… Its just a 5/8 wave on
70 cm, The same design really as any other 5/8 wave for any other band,
This type of 5/8 wave will work as a Loaded 1/4 wave on 2 mtrs… The
antenna would normally be used on a car and the metal body as the
groundplane, But here it uses the 1/4 wave radials to allow it to tune to
each band… Gw0wvl
Is there any site with plans?
You can also make a 5/8 wave of simular design to this for 2 mtrs,Just
up-scale the measurements for 2 mtrs… The antenna would also work as a
loaded 1/4 wave on 6 mtrs ( 50 mhz )… Another simple dual band antenna…
Gw0wvl
Where could I find some information about the loading coil — why it has
the specs that it does, why you chose 5 turns at 6mm diam, etc? I’m just a
very curious undergrad engineer 😀 73 N0SSC
Nice work mate I have used this designe before and they work quite well
easy to make for mobile use as well.
@George Rolph…Yes im aware of this, But as the de-tuning effect
is so small its not really a worry, almost anything placed next
to a antenna has a de-tuning effect..Slight re-tuning maybe
required but in reality ive found its not required, I dont know
if your aware, But some plastics contain more carbon than others..Its
generally the carbon in the plastic thats the problem…A way to
tell if the plastic your going to use is any good is to place a small
piece of it in the microwave oven and if it warms up its no good, If it
stays cold then generally its ok to use.
Hi Jim,
Thanks for the video I just picked up a Rigol DSA815-TG to do some
receiver alignment (I know over kill) but these units are so well priced I
couldn’t pass one up. Still need to pick up a return loss bridge for
antenna work as well. Keep the spectrum analyzer videos coming I like
watching them learning a lot.
Dave.