Shortened BOG Array

[Gr0undPlan3]

In the past, I had a 180 feet low Beverage (~3 feet) terminated in 470 ohms facing about 340 degrees. Antenna wire was THHN stranded fed to a transformer to 75 Ohm coax. It was quiet and worked. But it was 'facing' North so somewhat limited. I was also using a crude vertical at the time.

Then I put up a proper multi-band quarter wave vertical. Still quiet and omni-directional. I could hear much more than the Beverage, including noise, especially in the lower bands. The Beverage and crude vertical came down at this point and I used only the quarter wave vertical.

I have gotten to the point where I would like some directivity, especially in the lower bands. I have a HOA lot, so towers are out of the question.
To keep it stealth, I'm going to try a 4-way BOG array, that will be far shorter than ideal. I’ve had decent results with 180 feet. And, this is a RX only array.

To implement all four directions, I need a little over 1,000 feet of coax. I currently have about 600 feet. The feedlines eat up much of the coax since there are two equal lines per feedpoint. My longest run will be for the E-W Beverage, 400 feet of feedline. I will start with the E-W leg since I have everything I need to start on hand.

Also, it may easy to test F/B using WWV to the West. I should see a signal decrease when listening to WWV on the East leg compared to the West leg. Maybe I’m wrong or my F/B will be terrible.



The lengths listed above are the total length of the coax. The feedline run measures to just over 200 feet (x2). Sections D, E and F will require connecting each section into the total 218 feet. Not certain how I will join those sections yet.

The reversible BOG is based on section 2.15.5 in ON4UN’s Low-Band DXing. Excellent book with an excellent section on receive-only antennas. The concept is based on using both the braid and center conductor as two separate wires. 2:4 transformers wound on binocular cores are used at each end to terminate either the center conductor, or the braid.

Since my ‘wires’ will be on the ground, Z_SURGE is estimated to be 300 Ohms. I’m using 75 Ohm coax and my transformers (T1 and T3) are measuring between 305 and 308 Ohms.

The feedpoint contains both the feedpoint to the shack (2X) and the other 2:4 transformer for the antenna section. Gas discharge tubes (GDT) to ground rods are used at each end for lightening protection.



The end termination will go on the West leg and the feedpoint/termination will go on the East leg.



I’m currently getting rain at the QTH and I’m hoping to get the E-W leg installed externally this week. Much easier to pound ground stakes into soft ground. Not much rain recently and very dry.

I’ve also built an entrance panel with GDTs and braid-breaker transformers on each line. More on that to come as this progresses this week.

Thanks for looking.

[Gr0undPlan3]

UPDATE#1

ENTRANCE PANEL

The entrance panel is straight-forward.



Each coax/direction will feed through a GDT and then a 2:2 transformer to isolate common mode currents. There is a pair of double coax + ground that comes into the house for a total of 4 coax and 2 grounds. I’ll tie those outside grounds together and attach a ground rod for QTH ground. The inside grounds will attach to the entrance panel.

To check for losses through the entrance panel, I performed a 5 Vpp sweep from 600 Hz to 30 MHz with my SG and saw no loss and no spill-over to adjacent lines.



E-W Beverage – 255’

Physical length of the installed E-W Beverage is 255 feet and works surprisingly well.

Even in the AM broadcast band where the antenna is really short, I am able to null out a local AM station to the west of my QTH. 1270 AM WDLR 500 W. The N-S null is also strong with the major local stations to the south almost completely nulled. Did not specifically check yet, but under the assumption the clear channels in Cleveland and Detroit would be knocked down or nulled completely.



WWV is more difficult to null although there is a 3-5 S-meter drop listening to WWV on the east Beverage.

I appear to have mis-labelled the feed ports, east was actually west and west was east. Glad I waited to WX proof until after testing! Switched the feedlines to the correct ports and WX proofed them.

Due to tree roots, I was no able to get the feedpoint ground rod very deep. I’m going to add a second ground rod 5 or 10 feet away and bond it to the existing ground rod. I’ll bury the new one to ease mowing in the area when the time comes again next season.

E-W performance has surprised me, I did not expect much nulling considering the lack of space for a proper Beverage. Working on the N-S Beverage next.

[ThaDood]

WOW!!!! Some time, $$$$, planning, and some damn good engineering, applied to that BOG project. Mine??? After listening to a friend coax me to try that, I´ve compromised to using an idea of a W.O.G., Windom On Ground. About a decade ago, A friend of mine asked if I wanted old, ripped-up, commercial RG-11 coax, like hundreds of feet of it. Price was right, so ´YEAH!!!´. Sure, the #10AWG center conductor is totally contaminated, but I didn´t care, for my application of use. That 1/2¨ solid aluminum shielding, with that heavy-duty PVC jacket, makes the perfect Grounding conductor & Low FREQ Antenna. So, I used about 250ft of that trashed RG-11 to home-brew my own W.O.G. Beverage Antenna System. So, a 40-some foot run of RG-mini-8 coax, goes to one of my W2DU 4:1 multi-toroid current Balun, the 200W version with grey PVC piping. (The key was to keep this away from the noises of the house & road power lines.) Then, have one 100ft leg hug the soil as a crescent-shape down hill to the valley floor, and away from the road power lines. The other 150ft leg hugs the shoulder of the hill, then goes 3/4-way down hill, to stay away from the garage, where my AM1620, 3 meter antenna, is transmitting. So, real rime, or reason, to the lengths here? Um, no... In-house, a quick disconnect pig-tail was made to plug IN / OUT the Beverage Antenna Inputs of whatever rig I use.  This pig-tail has a terminal strip of opposing 1N4148 diodes for spike, and severe RF, reduction. The results? This is actually a better Medium Wave Antenna System, than the raised Windom. From like late February to maybe around Halloween, or later, the raised Windom gets an earful of lightning crashes from 40M, on down. (Even on 20M.) However, during Summer months, I can again listen to Medium Wave Broadcasts, listen to 160M HAM´s, 120M Broadcasts, WWV 2.500MHz, regional 75M / 80M HAM´s, regional 60M HAM, WWV 5.000MHz, 48M Broadcasts, and even regional 40M HAM´s and Broadcasts. Will it receive above that? Well, yes, but much, much, more attenuated signals. Anyway, Saturday nights, I can again listen to This Week In Music History on Philly´s 1210 WPHT on Saturday nights, and not get an earful of lightning crashes. (As much...) The lighting crashes are attenuated like -20dB, or more. On the 75M / 80M HAM Band, imagine having the quiet noise floor of 2M SSB, or even 432MHz SSB, for that low in FREQ! Yes... This W.O.G. is not a DX Champ of an antenna system, but it does allow me to hear something locally & regionally on these lower HF & MW bands. Now, LF, below 500kHz, I have lots of attenuation here. I fault this to the lower-end spec´s drop-off of the W2DU Balun. I can still just hear WWVB at 60kHz, but in the Winter, the raised Windom gets that from S+9 to S+20/9. Being Near-South, in SW West Virginia, I can routinely hear lightning crashes from Cuba, Mexico, & the Caribbean. So, my W.O.G. as effective as  Gr0undPlan3´s? No where near, but the fact that it is usable to me on those lower FREQ´s during the warm & hot season, made it a worthy project to me nonetheless.  Oh... One more thing, The W2DU Balun is grounded at the PL-259 Connector, which seemed to make a difference on RX sensitivity even more so, below 3MHz.  Do I have any photos of all this? Um, no... That´s kind of the idea as well, out of sight, out of mind, for the many that are non-RF conscience. Could, make for a nice H.O.A. hidden project??? Maybe... Anyway, all my take on this subject.