arlx-om2400

What's the trick in these two antennas for high gain?

http://www.demarctech.com/products/r...PDG112H22.html
and
http://www.hyperlinktech.com/web/hg2415u.php

First antenna is probably array antenna, but I don't have idea is this antenna on microstrip or with wire. I assume background plates is metal reflector and increase gain, but what's with second antenna

The second one with the circular radome is using and end fed set of dipoles that are attached to each other end to end with phasing coils between. this is bent from one piece of wire. It is about 20 wavelengths long.

The first one looks like an array two wide by ten high of elements in front of a reflector.

I agree with flatulent, the second one is also so-called collinear because this is series-fed array of dipoles with inphase currents. This results in omnidirectional pattern.

I think there aren't coils as phase shifters but pieces of lines.

Regards,
Eirp

hi .. have a look here:
http://www.wlan.org.uk/antenna-page.html
http://www.guerrilla.net/reference/a...ollinear_omni/
you will se the construction of 'multi' dipole vertical array ;0))
but be very carefull with vertical pattern .. the beam will be extreamly narrow so you can loose coverage below antenna. Plkay a little bit with downtilt or use 4 panel antennas and splitter

regards

cancel

hi,
I do also agree with the second description: it is a collinear array of dipoles with some phasing between them to get the downtilt.
The first one is probably an array of printed dipoles with a back-plate. I think they are dipoles based on the H plane pattern which is quite broad. patch antennas do not give so much beamwidth

Yes, for first case they should be dipoles and not patch antennas even first antenna can be similar to second one with a reflector.

I had taken apart an antenna like the one with the pipe radome. Now that I remember better, they used quarter wave stubs as the phase shifters beween elements. The stubs were bent into a circle so that they would fit in the pipe.

The metal part at the bottom that is used for the mechanical mounting also serves as the impedance transforming network. The inside diameter changes over several values from the bottom to the top. The antenna wire goes right down the center and connects to the center conductor of the coax socket at the bottom.

Thanks all!

I'm find collinear antenna manuals on this locations:

http://www.guerrilla.net/reference/a...ar_omni_lowpwr
http://www.geocities.com/lincomatic/collinear.html
http://www.aerialix.com/kits/arlx-om...-all-inst.html

Can I use collinear antenna and metal plate in background to made 180 degree directional antenna and what will be with gain?
As I can see in this manuals they are use phase shifters like coils, what effect will have metal plate on this phase shifters?
What will be with dimensions of based collinear antenna because effect of metal plate?

Putting any omnidirectional antenna in front of a plane reflector will increase the gain by 3-6 dB.. It usually reduces the feed impedance.

Have you thought of a very directional antenna like a Yagi-Udi? You can buy these with 20 dB gain from places like D-Link.

Another thing to keep in mind is blockage by buildings. Mounting your antennas at high points will help.

I'm looking for 120 degree of directional antenna.

in your 120 degree case, you will be restricted to the vertical in front of a reflector. If you do not have the test equipment to measure the impedance effects on the antenna when it is in front of a reflector, you would be better off not having the reflector.