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[K4RVN]

I plan to install a bent 40 meter dipole using my remains of a three element quad. I have enough parts for a two element in good condition now. It will be in a loop configuration with a total wire length of 66 Ft. The top and sides will be approx 20 ft and the bottom wire will turn in 3 ft on each side with nylon cord connecting them.  It will be fed with coax at the top using a typical dipole connector but with a hairpin match to adjust the impedence. The reflector will be a length of 70 ft wire and connected at the bottom with nylon cord. The reflector will be 14 ft behind the driven dipole. Has anyone ever done this or modeled such a design? I am not a theory guy just build some wild ideas at times. Some work some don't. This will be on a 50 ft tower and will rotate if it works.  I would appreciate you antenna persons opinions on this idea and thanks for
any input.


Frank K4rvn

[K4RVN]

Doing some looking for hours on the net, I ran across a similar design tonight called the square pole. It however did not have a reflector and the lengths at tie points were different as well as the feed point. I am thinking of feeding mine at the top unless someone tells me better. Here is a link if interested. I had not seen this before and can find little on bent dipoles, but some info is available. I hope I can have a 40 meter 2 element dipole at about 40 ft average that rotates with some gain when the weather warms. After looking at the article more closely, I read that it installed as a horizontal loop while my antenna idea will be vertical with a reflector but horizontally polorized. I read w8Ji's comparison of a quad to dipoles and see where he is coming from
in that. I don't pretend to understand the rest, but enjoyed reading it.

http://www.zerobeat.net/g3ycc/squalo.htm

[K4RVN]

For your info, I cut the dipole to formula, 468/F,  put it on a quad frame and pulled it up into a tree with the bottom 12 ft above ground. The horizontal is 9 ft on each side of the center insulator at the top. The side wires each come down on the frame about 18 ft then the remaining wires go toward the center tied together with nylon cord. The bottom wires are 12 ft off the ground. The total wire length is a full half wave of about 66 ft cut for 7.2 mhz. I called CQ running 750 watts and a European station answered & gave me 59 plus signal report. The bent dipole looks like a square loop fed at the top center and open on the bottom connected by nylon cord. SWR at 7.145 is less than 1:5 to 1 and it loads great without a tuner barefooted or with the AL 80A. It is bi directional but I can point it by swinging it on the rope supporting it as I put cords on the bottom quad spreaders, I get a small amount of rotation before the tree gets in the way. My plans are to mount the driven element on a boom along with a reflector 16 ft away since my boom is 16 ft.  I am going to put it on a 50 ft Rohn 25 with a rotator and a Glen Martin H3 hazer along with a 10 ft mast It will be up about 40 ft average height above ground and I hope to have a 2 element rotating 40 meter beam. I get excellent reports to Texas, Wis., Florida and Europe with the one element so expecting some front to back and gain with the added reflector. If the reflector does not work, then I'll use it as a rotating half wave bent dipole. In general I get a lot of contacts on 40 meters with 59 plus reports at 12 feet to the bottom wires from ground. At the top feed, I used a home brew coax choke balun from EI7BA design left over from my old quad. It is fed with 100 ft RG 8X from the wireman nothing special. It appears very narrow banded but with the AL 80A I can run about 700 watts across the entire ssb portion without increasing the drive from my transceiver.
It feels great when something actually works better than expected.

Frank

[K4RVN]

As a follow up, I did put the 40 meter bent dipole on a 50 ft tower with a hazer. Driven dipole and reflector are are installed on 20 meter quad frame elements. The antenna loads and has front to back. Running 500 watts and getting mostly 59 plus reports in the states and DX on 40 meters. In effect I have a 40 meter rotating beam so met my goal. Feeding it with coax and a homebrew coax choke near the feedpoint on the top wire of the dipole. Horizonta dipole is only 18 ft, then wire is bent down and then in at the bottom spreaders and tied with nylon cord.
Feed point must be near 50 ohms as it loads across the entire 40 meter SSB portion, no tuner required.
I am most pleased with the crazy design and confirmed W4RNL's article that said in effect that one could bend a dipole in various shapes without distracting very much of the performance from a horizontal dipole. I have not put my antenna analyser on it yet, just enjoying it at the moment. Easy way to get a 40 meter full size beam with a smaller footprint than usual.

Frank

[VE3WMB]

Frank :

This idea is similar to the Dk9SQ Loop antenna.  The antenna is essentially a diamond shaped 20m full wave loop that can be used multi band (it is fed through a balun with some sort of parallel feed line) at one of the side vertices.  On the opposite vertex from the feed point there is a jumper that
can be opened so that the loop becomes a folded up vertical dipole on 40m.  Mounted on the 10m
DK9SQ mast the antenna (including the configuration as a loop)it is essentially omni directional because of the low height but it works quite well. 

Here are a couple of links :

http://www.wimo.de/spieth-portable-hf-antennas_e.html

http://www.eham.net/reviews/detail/1646


Michael VE3WMB

As a follow up, I did put the 40 meter bent dipole on a 50 ft tower with a hazer. Driven dipole and reflector are are installed on 20 meter quad frame elements. The antenna loads and has front to back. Running 500 watts and getting mostly 59 plus reports in the states and DX on 40 meters. In effect I have a 40 meter rotating beam so met my goal. Feeding it with coax and a homebrew coax choke near the feedpoint on the top wire of the dipole. Horizonta dipole is only 18 ft, then wire is bent down and then in at the bottom spreaders and tied with nylon cord.
Feed point must be near 50 ohms as it loads across the entire 40 meter SSB portion, no tuner required.
I am most pleased with the crazy design and confirmed W4RNL's article that said in effect that one could bend a dipole in various shapes without distracting very much of the performance from a horizontal dipole. I have not put my antenna analyser on it yet, just enjoying it at the moment. Easy way to get a 40 meter full size beam with a smaller footprint than usual.

Frank

[K4RVN]

Thanks for reply. My antenna is a 1/2 wave 40 meter dipole bent into a square with the ends tied togetherwith nylon cord at the bottom horizontal. It is in effect open and not a closed loop. It is fed at the top center horizontal wire with RG8x and a coax choke. In addition I have a reflector which is longer and spaced 16 ft away by the two element quad boom. Worked F5 BDV last night, given 59 plus 5, received him 59 plus. I was running 650 watts.
Also I5 ZSS answered my CQ gave me 59 in Italy. No tuner or special feeds required. I also found it loads great on 15 meters and very well on 17 meters. I don't see a whole lot of similarity between my bent dipole and the link you sent. I do appreciate the information and realize that you don't have a photo of mine to see how it is constructed. It is just a dipole and reflector like a fixed beam but attached to a quad frame, rotates and is bent to suit the quad spreaders. A 20 meter quad usually has a driven wire element of about 70 ft and the dipole is only 66 ft so it worked out fine with the ends held together with nylon cord. Thanks again Michel. I did not originate this bent dipole idea just used the bent dipole info someone else posted to use materials on hand so I could have a two element beam that rotates.

Frank