1/8 wave spacing and dual band

[WA1GFZ]

Pretty much agrees with my findings but I'm at 60 feet. It sure likes 140 degrees phasing.  I need to build up a couple lengths of coax to even the two runs and a phasing harness. Then I can hook up the transfer relay and take it out for a ride. Those FB numbers are interesting but wonder if I can ever get close. I figure closer to 15 dB in the real world.

[Steve - WB3HUZ]

Yea, that F/B will hold only over a very narrow freq range. If you can get 25 dB over a reasonable range, you are doing good. Got a report of 30 dB with my two loops on 40 meters tonight but that's one data point/propagation path/time.

The phasing lines for my 43 foot model would be 92.9 and 124.1 feet with 75 Ohm, 0.85VF cable, or 71.7 and 96.4 feet with 75 Ohm, 0.66 VF cable. The feed-point Z at the junction of the two cables would be 100 + j6 Ohms.

[WA1GFZ]

My two lines are RG214 and RG213. 95 and 142 feet. I added some to the 142 to phase it to the west. I figure 140 degrees at .66 VF is around 60 feet.
I have not looked at the VSWR but Viking 2 drives it. I have 2  42 foot sections of RG11 as the splitter driving it from the old set up. 

[Steve - WB3HUZ]

Remember that the phase shift is not going to be equal to the product of the length of the coax and the VF.

[WA1GFZ]

I'm confused why not?

[Steve - WB3HUZ]

Because the lines aren't matched (flat).

[WA1GFZ]

Are you saying VSWR changes the delay time? I know the lengths are not matched but I will just add coax to the short one to even them out before I add the phaseing. As Tom suspected my reference antenna is effecting the performance. In RX I can change the signal level of the phased antennas by shorting the coax of the reference antenna.  I also have a hunk of wire about 100 feet long stuck in the trees near the west dipole.

[Steve - WB3HUZ]

Yes. Specifically, it changes the phasing or delay between voltage and current. You will also likely get magnitude difference to the two antennas that will also affect the pattern.

[WA1GFZ]

Ok, I see what you mean. I know my two inverted Vees are a bit long 62.5 feet on a side but they are all the same lengths. My old phased array I was able to adjust feed line lengths to get it dialed in.
I thinking of changing the two antennas to two 40M loops and screw 80 meters until I can get another element into the woods against the reference antenna. Too much going on between both antennas.
How do you have your loops diamonds or square and where is the feed point?
My old 20, 15, 10M quad I did diamond configuration. I could do square if i added a boom to the side of the tower but prefer not to add a pole under the LPDA.

[K1JJ]

Frank,

Unless you have the height to play with, (with 85'-90' at the apex to support 40M loops) the average height of the loops will make the take off angle inferior to a pair of 40M inverted vees.  The pattern will be sharper and lower with the inv vees including high angle suppression.

I have a 3el 40M inverted vee wire Yagi supported at the 70' APEX level with the ends at about 55'.  The avg height is about 63'. (Plus RF ground depth)  Ask Huzman - we did a f-b test on Saturday against the NE Yagi and found the f-b was approaching -45db++.  I found the average height "sweet spot" on 40M to be with inv vee apexes at 70' and the ends as high as you can get them.   Phased inv vees shud perform as well.


If you have 85'-90' apex height to play with, then it won't matter if you use loops or inv vees.   


Yes, I would go for an optimized 40M array there instead of 75M.  You will be very competitive with the big guns and have much more fun on 40M with an array at 1/2 wavelength high above ground.  On 75M, you will be less than 1/4 wave (avg) and back into the back of the bus. No fun that way.

Might as well be a lion for a day rather than a sheep for a lifetime....

T

[Steve - WB3HUZ]

They are delta loops, pointy end down (upside down triangle). The feedpoints are at the bottom. I will send you an email later today with more info.

Ok, I see what you mean. I know my two inverted Vees are a bit long 62.5 feet on a side but they are all the same lengths. My old phased array I was able to adjust feed line lengths to get it dialed in.
I thinking of changing the two antennas to two 40M loops and screw 80 meters until I can get another element into the woods against the reference antenna. Too much going on between both antennas.
How do you have your loops diamonds or square and where is the feed point?
My old 20, 15, 10M quad I did diamond configuration. I could do square if i added a boom to the side of the tower but prefer not to add a pole under the LPDA.

[WA1GFZ]

Gee that sounds very easy to do, and puts the average height further up.
I don't want to cut the 75 meter elements so would need to replace the to do  inverted vees. Yes, send me the poop on it.