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Homebrew Quad 1900MHz Antennas

Posted: Thu Oct 31, 2019 9:50 am
by terryjett
Had some time on my hands while the wife was attending a conference down in Austin TX. Thought about spending it tossing a few brews/fishing with the buds, but decided to do something more constructive:)

I have built quite a few wifi 2.4GHz quad antennas over the years and each one of them impressed me with performance+distance. So why not try them for at&t band 2 and 4?

I centered the quads wavelengths at 1900MHz (band 2). They "should" also pull in 1715MHz (band 4 uplink) & 2115MHz (band 4 downlink). Understood from the get-go that may have issues with the frequency spread but what the heck, lets try it.

Used this site to get going: https://buildyourownantenna.blogspot.co ... hz-3g.html

Also BiQuad / Double BiQuad Antenna Calculator here: https://buildyourownantenna.blogspot.co ... lator.html

Good construction tips here: https://martybugs.net/wireless/biquad/

Tip: You can easily solder to galvanized sheet metal, but double sided (or solid)copper board better. I used old sides from a desktop computer because it needed recycling. Removed all the paint and used a small torch to "tin" the areas would be soldering to. I then used jb weld to seal and stabilize the 12ga copper wire + sma female connector.

Used SMA female connectors simply because had a surplus in my war chest. If making something permanent, I would go with N-type connectors. Also used RG58U feed because that is what I had on hand. My run is only 12 feet but 58U is very lossy. Normally would use at least lm-240 coax for these frequencies.

Keep in mind that all of this was thrown together over 2 days because it was decided that I really needed to spend some time fishing with my buds:) Bottom line is: not the best antenna design job, but love experimenting and that was what the project was all about!

My old dish that was left behind my directv:
dish_antenna.jpg
BiQuad Feed:
dish_antenna_biquad_feed_2.jpg
BiQuad Feed Again:
dish_antenna_biquad_feed.jpg
My Double BiQuad Flat Panel:
double_bi_quad.jpg
Both are in use on the WE826 with MC7700 pulling in the 10MHz Band 4. My speeds are good. The antennas are less than 10 feet off ground level (less ladder work - getting older). Antennas are about 4 miles from tower and 1 mile of that is pretty heavy with old growth hardwood about 60-80 feet tall.
combo_antenna.jpg
My results taken around 8am this morning while area is active with people on way to work/school:
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There are 100 things done wrong here, but do not care. The focus was to see how the quads work with at&t bands 2 and 4. I had fun doing the "beta versions" and know exactly how to construct my "version 1" antennas in a few months.

Now get out in the shed, build yours and show them off!

Re: Homebrew Quad Antennas

Posted: Thu Oct 31, 2019 8:57 pm
by swwifty
great post! Quite good performance for your first try at this! I'm quite impressed.

I'm gonna be trying my hand soon at making some antennas. Just got my amateur radio license, and I'm gonna be building some directional antennas for VHF/UHF and the HF frequency range.

Re: Homebrew Quad Antennas

Posted: Fri Nov 01, 2019 6:34 am
by terryjett
Thanks @swwifty! Built quite a few wifi antennas over the years and figured would try my hand at these.

My yagi's are mounted about 30ft up and out perform my homebrew ones (not by huge amount though). Most agree that the double biquad have a gain around 13dBi which makes them about double my yagi's gain. Adding the lip makes the quads little more directional.

When I build my next double biquads, going to mount them up about same height as current yagi's and see how they compare.

Re: Homebrew Quad 1900MHz Antennas

Posted: Thu Nov 07, 2019 12:38 pm
by terryjett
Got a new design to test. First results from my home were not bad. Going to take it out to remote area at nearby lake and see what she does with at&t tower located 6.3 miles. The area is surrounded by pine trees and those pine needles are known to suck up 1900MHz (band 4 too).
dishHD-1900MHz-biQuad_sm.jpg

Re: Homebrew Quad 1900MHz Antennas

Posted: Fri Nov 08, 2019 9:21 am
by swwifty
very cool!

Re: Homebrew Quad 1900MHz Antennas

Posted: Thu Nov 14, 2019 5:29 pm
by terryjett
Thought I would post these pics of my BiQuad Construction steps. Not a full tutorial, but gives you idea how I build mine:)

Working with small SMA female chassis mount:

I use the leather punch as form to bend 14ga wire into circle. Like this method because makes a better (and easier) solder joint.
sma_connector.jpg
sma_connector2.jpg
Basic steps BUT BE SURE to get your measurements close as possible for target frequency:
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Have few more images to add but reached limit allowed in post...

I highly recommend you try and get your bend radius tighter than mine. I used 12ga wire and it is much harder to get tight radius compared to 14ga. I like 12ga better because it makes a stronger biquad but harder to bend:)

Re: Homebrew Quad 1900MHz Antennas

Posted: Tue Dec 10, 2019 5:19 pm
by AntennaRaul
Nice work on those Bi-Quad antenna structures. Ive got a pile of leftover 1900 Mhz 4-patch PCB (14.5dBi) and back plates. The PCB mounts aprox 5mm above the back plate and is fed by a pin or center of the grounded coax. I can mail you a set if you PM with an address. Its free. Rather see em in use than dump them.

Re: Homebrew Quad 1900MHz Antennas

Posted: Tue Dec 10, 2019 7:40 pm
by terryjett
Thank you @AntennaRaul. PM sent.