Quad Double quad ?

mr_wlan · 08-03-2002

Hi,

I've just written up the quad double quad which funnily enough gives around four times the gain of the single double quad.

the article is located at http://www.frars.org.uk/cgi-bin/render.pl?pageid=1162

regards,

mr_wlan

lincomatic · 08-03-2002

very nice, mr_wlan, thank you for sharing it with us. i will surely build one in the not-too-distant future.

btw, do you have any idea if this design is any good?
i got it from:
http://patraswireless.net/antennas.html

also, do you use software to model your antennae? and if so what is it?

mr_wlan · 08-05-2002

Hi Linco,

well that antenna you provide a link to has an impedance by it's nature of 25 ohms, this means that the simplest way to match it to 50 ohms is to use a pair of them, phased up. Using a 3/4 wave transformer will take 25 ohms and give you 100 ohms, 2 100 ohms in parallel will give you 50 ohms, and your feed point.

as for the antenna modelling software - that's a secret!

cheers,

mr_wlan.

ew123 · 08-06-2002

Hello mr_wlan

I have been searching for a phased array antenna for weeks without success. So your antenna is a real hit.

You use UT 141 coax for the phasing assembly. I suppose the exact length of the assembly is important (is this so?). If I want to use different coax (RG 58), what are the parameters I have to pay attention to?

Thanks in advance

ted · 08-06-2002

I am not a microwave expert, but for my knowledge RG58 is a bad choice for these frequences.

And, yes, because these pieces of cable are impedance transformers, the exact (electrical) length is critical. So, if you replace the UT 141 with anything else, there is a fair chance that some adjustment is needed.

ew123 · 08-08-2002

I'm searching for information about the calculation of these phasing assemblies. Does anybody have some information about these matching lines?

ppp1 · 08-09-2002

Hi there,

I was searching myself for low-profile high-gain atnennas and I came through with the attached file. Matching impedance of this double-eight design is highly dependent of the gap (spacing) between the reflector plane and the actual radiating element.

Although I dont have a VSWR meter for 2.4GHz, practical measurements (against Lucent 24dBi parabolic grid) shown that making the gap 15mm results with the best performance (approx. 14dBi). Someone can safely say that this gap provides the construction with a impedance match somewhat near 50 Ohm.

Another interesting antenna design is the one the following link reffered to: f5ad.free.fr/ANT-QSP_F1AIA_Sextuple_Quad_2310.htm

In the near future, I will attach my USB client on the back of the reflector plane, thus making some short of embedded antenna. The only cable run to my desktop PC will be the USB cable itself. No RF cable, maximum EIRP. Check patraswireless.net/devices.html for more.

Regards

Kostas with PatrasWirelessNetwork

PS: Three more postes will be commited in order to send the pictures.

ppp1 · 08-09-2002

Post number 2

ppp1 · 08-09-2002

Post number 3

ppp1 · 08-09-2002

Final post

Pow · 08-20-2002

The same can be done with four dipoles. Will give you about 15 dBi gain.

http://pow.za.net/panel.html

Pow · 08-20-2002

ppp1, lincomatic:

the problem with double doublequiad (double eight) is that its cool for horizontal polarization but not so cool for vertical polarization.
In your pictures it is horizontal polarization. Turn 90 degrees to get vertical polarization.

This design is used as tv antenna where horizontal polarization is common.

When using vert polariz double doublequad, azimuth half power beamwidth is way smaller than elevation.

(correct me if i'm wrong)

08-03-2002	#1 (permalink)
mr_wlan Registered Member Join Date: Apr 2002 Posts: 40	Quad Double quad ? Hi, I've just written up the quad double quad which funnily enough gives around four times the gain of the single double quad. the article is located at http://www.frars.org.uk/cgi-bin/render.pl?pageid=1162 regards, mr_wlan

08-05-2002	#3 (permalink)
mr_wlan Registered Member Join Date: Apr 2002 Posts: 40	the quad antenna Hi Linco, well that antenna you provide a link to has an impedance by it's nature of 25 ohms, this means that the simplest way to match it to 50 ohms is to use a pair of them, phased up. Using a 3/4 wave transformer will take 25 ohms and give you 100 ohms, 2 100 ohms in parallel will give you 50 ohms, and your feed point. as for the antenna modelling software - that's a secret! cheers, mr_wlan.

08-20-2002	#11 (permalink)
Pow Registered Member Join Date: Aug 2002 Posts: 4	For dipoles phased array The same can be done with four dipoles. Will give you about 15 dBi gain. http://pow.za.net/panel.html Last edited by Pow : 08-21-2002 at 07:21 AM.

08-20-2002	#12 (permalink)
Pow Registered Member Join Date: Aug 2002 Posts: 4	double doublequad problem here ppp1, lincomatic: the problem with double doublequiad (double eight) is that its cool for horizontal polarization but not so cool for vertical polarization. In your pictures it is horizontal polarization. Turn 90 degrees to get vertical polarization. This design is used as tv antenna where horizontal polarization is common. When using vert polariz double doublequad, azimuth half power beamwidth is way smaller than elevation. (correct me if i'm wrong)

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08-06-2002	#4 (permalink)
ew123 Registered Member Join Date: Apr 2002 Posts: 11	Hello mr_wlan I have been searching for a phased array antenna for weeks without success. So your antenna is a real hit. You use UT 141 coax for the phasing assembly. I suppose the exact length of the assembly is important (is this so?). If I want to use different coax (RG 58), what are the parameters I have to pay attention to? Thanks in advance

08-06-2002	#5 (permalink)
ted Stumbling on Join Date: Aug 2002 Location: Houston,TX Posts: 47	I am not a microwave expert, but for my knowledge RG58 is a bad choice for these frequences. And, yes, because these pieces of cable are impedance transformers, the exact (electrical) length is critical. So, if you replace the UT 141 with anything else, there is a fair chance that some adjustment is needed.

08-08-2002	#6 (permalink)
ew123 Registered Member Join Date: Apr 2002 Posts: 11	I'm searching for information about the calculation of these phasing assemblies. Does anybody have some information about these matching lines?