Fan dipole

[K5IIA]

I would like to see if someone would model an antenna for me.

Right now I have my 80m phased array at 80 feet high. 55 foot spacing and was wondering if I added 40m wires to it and made a new phasing line I could switch in if there would be any way it may do better on 40m then my 55 foot high inverted v I have right now.

Both the array and inverted v are broadside north.

It's just a thought and would like some input.

I looked at the patern in the book of half wave spacing and it is by far not as good as .25 spacing but if it looks like it may do a little better I would be up to trying it out.

73 y'all.

[WA1GFZ]

put up a 40 meter inverted vee in the middle and do 3 elements. Switch the two outside between director and reflector.

[K5IIA]

I don't think I can do that. That is an awesome idea though.

[Steve - K4HX]

I'll model it for you this weekend Brandon. It should work FB with the correct phasing.

[K5IIA]

thanks steve, i was going to just email you but i figured maybe someone else could use the information if it amounted to anything. i would really appreciate you doing that.

man if it would do better then my single dipole at 50ish feet i would really like that. and woudl even save some room to boot.

this site is really a great resource for the am/ham community.

[Steve - K4HX]

See the plots below. The red is the pattern for the phased dipoles and the dotted line the inverted-V. As you can see, you don't get nearly the front-to-back at the lower angles that you get with your 80 meter phased array. But you do get a nice amount of back side rejection at the mid angles. There is also a high angle secondary lobe. This occurs because the array is well over one-half wavelength high.

That said, you still get 4 dB forward gain and the take-off angle is over 10 degrees lower than the inverted-V. That's good for longer distance contacts. You might consider lowering the inverted-V some to make it more optimum for close-in contact. Then you have the best of both worlds.

I picked a phase delay of 100 degrees. Larger angles give you a slight increase in forward gain but the F/B gets worse (far more than the change in forward gain). Smaller angles improve the F/B but you lose forward gain, as much as 1 dB when you get to about 85 degrees. Pick your poison.  

I didn't try bending the ends of the dipole in towards each other. That may increase the coupling or effectively decrease the spacing which may improve the F/B.

[K5IIA]

  wow thanks steve. that is awesome. i may add the wires tomorrow.

i wonder what woudl be better to actualy use the same coax as the 80m dipoles and just make it a pretty steep inverted v. and possibly also cheat the ends towards the opposite dipole some.

or just run some more coax up the coax i have now and maybe stop at the 40 foot level or so and use seperate coax for the 40m dipoles.

either way i will check it out and see how it does..

you get used to antennas with a little gain and it spoils you.

i have a 2 element quad for 10-20m and the array for 80. now i may have a tad of gain on 40.

only wish it was aimed at europe. my two supports are 17 degree east of north so that is the direction i will be stuck in for a while.

thanks again, i just signed out we been out there playing in the static on 75m

[Steve - K4HX]

I heard you on 75 meters last night. You were coming through the static no problem!

It's probably more work but I would mount and feed the 40 meter dipoles separately from the 80 meter dipoles. Your 80 meter systems seems to be working so well, i would want to mess with it.

[W7TFO]

Good applicable info, thanks from me too!

73DG

[WA1GFZ]

check the antenna section on Steve's 2 element delta loop antenna for 40 meters. It doesn't take much space but works very well.
I duplicated his antenna upside down with a 20 foot boom on my tower.
I have a good VSWR across 40m. A relay flips the pattern.

[WD8BIL]

I duplicated his antenna upside down with a 20 foot boom on my tower.

Frank, Are you corner feeding that antenna?

[WA1GFZ]

No, Center of bottom leg. I have 4 beads on the RG11 at the feed point. I think it was about 17 feet of RG 11 to the relay box. The top of the antenna is up around 50 feet maybe a bit higher. Performs well. I bet it would rock up higher.
Reflector the coax is shorted then feed the front element. I used a type n transfer relay. Check the antenna section the thread covers it.
I now have 2 feed lines into the shack to play with HPSDR beam steering. I have not tried switching from the shack. I have 2- 50 foot lengths of LMR 400 to the shack so short may need to become a stub to get it right.