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[Articles Home]  [Add Article]  

160 Inverted L, Welcome to Winter

from Bob Raynor, N4JTE on October 30, 2012
View comments about this article!

"Editor's Note: Due to the popularity of some of eHam's older articles, many of which you may not have read, the eHam.net team has decided to rerun some of the best articles that we have received since eHam's inception. These articles will be reprinted to add to the quality of eHam's content and in a show of appreciation to the authors of these articles." This article was originally published on: 12/10/2009





160 Inverted L Antenna; Welcome to Winter!

Submitted by N4JTE.

Between watching unending Law and Order repeats and the XYL's Lifetime movie sagas, compounded by a dead 40 meter band here at night, I became so totally bereft of late night activities that I got the bug to get back on 160 meters again with something that would fit in my backyard. I have had, in previous QTH's, the luxury of a full size 160 dipole, those were the days.

Well, 240 plus feet at any reasonable height is beyond my backyard limitations as I am sure it is, along with many of you.

The 160 band is to me, a throwback to my AM and SWL days as a youngster when I would lay in bed at night with my crystal radio and listen to all the AM broadcast stations I could discern and check them off on my Knight's Radio Log. Those days, are to me, the genesis of my love for the magic of radio, some of those AM stations are still legendary!

Enough nostalgia.

I wanted to get back on the band with a respectable signal and try out the much discussed and prevalent 160 inverted L antenna. Previous to the inverted L, I tried a few ideas, some of which I am sure others have attempted also.

PREVIOUS ATTEMPTS:

1; 80 meter dipole, coax fed. Whew, lucky I did not burn something up, I know why it stunk but there are still some out there that figure if their good old trusty tuner loads up and somehow a length antenna seems too work on 160 they are good to go, NOT! Besides the neighbors getting tvi, your tuner and feedline were probably contributing to global warming.

2; 165 ft. 40 edz at 60 ft. ladderline fed. I really thought this antenna would work as its only 60ft. short. The fact was that my 3kw tuner told me that with anything over 100 watts, I was dreaming, as Christmas came early with all the flashing lights inside the tuner.

3; The good old G5RV with the shorted feedline and ground plane approach. I'm sure I remember a contact or two on a quiet night but pretty lame imho.

160 inv L

.0x01 graphic

There are a lot of 160 designs out there on the internet with quite a few adding coils etc to match shorten verticals, or top loading with various configurations. My feeling is that the coil losses and tricky matching problems with top loaded wire antennas make the inverted L the way to go for simplicity of construction and relative ease in matching 50ohms.

The inverted L is what it is; picture your Hamstick or any vertical and bending it 90 degrees halfway up and expecting some improvement over a nice simple straight vertical. Let's be aware of the physics involved and keep our expectations within reality.

But: That's the mystery and fun unique to the 160 band, anything that approaches a well thought out antenna, even in a restricted place will compete well. The really big guns with the phased 120 ft towers and 4000 buried radials only show up for the contests. The rest of us peons have a pretty level playing field when we are content to work a new state or keep in contact with friends around the country, with the occasional DX station popping in to say hello.

THE CONSTRUCTION:

The best I could do here was to get the old trusty 2oz weighted fishing line over my now bare 65ft. maple tree. Hobby money is tight here so I scabbed together 120 ft of insulated # 14 wire form previous endeavors and pulled back some masonry line. Taking care to keep the ends from tangling, the string was attached to the 60 ft. midpoint of the insulated wire and hoisted up to the top of an outside branch on the tree with the feed point end about 6 ft. off the ground.

FIRST ATTEMP:

Because I had nothing better on first thought and it was getting dark I ended up having to slope the remaining 60 ft. to a tie off point in the backyard which resulted in the end at about 10 ft. off ground. I hooked up two raised insulated radials at 120 ft. long each and hung them up at 6ft. high along the wood fence. Definitely not as symmetrical as I would have preferred with some zigs and zags thru the available branches etc. but ran them at 180 degrees from each other. Be advised there will be a lot of voltage on the radial ends and make a supreme effort to isolate the ends from any human contact.

RESULTS:

Not bad, first of all the amp, AL80B, was finally showing some life and providing 400 watts indicated. Reports were good from local to 1500 miles out but the S/N, noise was horrendous, so I figured it was time for some improvements.

SECOND ATTEMP:

Well, I was happy to be heard and the amp and 3kw tuner were silently applauding my work so I figured lets work on the noise situation. I figured out a way to get the horizontal portion over a nearby tree at about 45 ft. high, and try to get closer to a flat top configuration, but unfortunately it is only about 40 ft. away. End result was that the last 20 ft ended up coming down in a vertical direction to the tie off point, sorta ended up with a skewed inverted U configuration.

Voila! Ended up with a relatively flat 1.5 to 1 on 1865. I know that can be misleading, especially when using a bizarre shaped vertical, but it works. See note #5 in final comments.

FINAL COMMENTS:

1; If you are in tight restricted environment, the inverted L will get you on the air with a respectable signal and good match to 50 ohm coax.

2: Yes it will be noisy in an urban near field environment; I use my 40 meter antenna as a listening antenna when my local noise competes too much.

3; I placed a 1 to 1 current balun at the feedline junction; I did not see any significant noise reduction.

4; From talking to other Hams more advanced and experienced with the 160 inverted L, I found a few that liked the 3/8 wl configuration as it moves the current point further up the antenna and improves efficiency beyond the 28% we can expect from the inverted L. However I believe the 3/8 configuration is adding more horizontal polarization as a trade off for better efficiency which is fine if your interests are more in line for closer in contacts. I don't see any major signal loss on close in stations but the inv L definitely shows it's worth beyond 800 or so miles, (whose counting ?) as compared to a 165 ft. flattop at 60 ft.

5: If you build it, I offer the following insights from my experiment. Going the raised radial route is the only way I could consider this or any vertical design with my rocky conditions, your mileage may vary, but read up on them. If you do use raised radials make every effort to run the feed line away at a right angle if possible, mine isn't. As mentioned, a 1 to 1 current balun is a big MUST; it will reduce any stray induced current on the coax shield.

My MFJ analyzer indicated 40 ohms resistance and about 1.2 to 1 swr. Anything way above or below that number should tell you that your ground plane is inadequate or you have common mode current problems.

To achieve your best match, prune the horizontal section length.

Lastly, the hard part, try to make the vertical section as tall as possible and if you are concerned with a DC path to ground while using elevated radials, throw a choke between the coax shield and the ground rod or equivalent. Do not just hookup the coax shield directly, unless you like talking to worms.

FINAL FINAL COMMENTS:

The setup as laid out in this article is working than better than expected and has reawakened my appreciation for the challenge and fun to be found on the 160 meter band. It is noisy at times here in upstate NY with my backyard surrounded by commercial businesses and transformers for the extended care facility 100 ft away, (there, but for the grace of God go I) so I use my flattop 40 as a backup receive antenna when it gets too annoying.

Try it out, the inverted L is as cheap as it gets and will give you a horizontal and vertical sky wave easily matched to coax. Definitely more entertaining than the Lifetime Channel!

Don't forget; 160 meters separates the men from the boys, see you there!

Tnx for reading,

Bob

Member Comments:
This article has expired. No more comments may be added.
 
160 Inverted L, Welcome to Winter  
by K3VAT on October 30, 2012 Mail this to a friend!
Thanks for republishing the 160M Inverted L article. This antenna and those of similar design will get you on the air. Those wanting a bit more of a technical explanation on short verticals and possible alternatives may want to read a recent article of the same name here: http://rudys.typepad.com/files/short-160m-verticals.pdf

GL, 73, Rich, K3VAT
 
RE: 160 Inverted L, Welcome to Winter  
by W4VKU on October 30, 2012 Mail this to a friend!
I built my inv-L out of #14 gauge multi-stranded wire.
It runs 70 vertical and then horizontal for 25ft and then vertical down another tree.

With about 15, 72ft radials and 6, 59ft radials, i was able to get the swr around 2.4 around 1.82mhz. I
tried adjusting the vertical length, and found that
i had to fold back by almost 10ft from the original
130ft to get the SWR below 3:1.

It works very well. I was able to work DR1A,PJ2T,CN2R,HK1NA,C50C.... over the CQ WW SSB
contest.

Now on to try an 80m L (70ft long)to use the same
radial field and separated from the 160m-L by 2ft
and selected by a remote coax switch.
I am trying this to avoid
adding a trap in the single 160/80m L configuration.
Fingers crossed. Already have a 80m G5RV @65ft, but
am sure the 80m inv-L will help with the long haul.

Any thoughts, tips? Please fire away.

Good luck.
73s
krish
w4vku

 
RE: 160 Inverted L, Welcome to Winter  
by K3AN on October 30, 2012 Mail this to a friend!
My inverted L is 130 feet in total length, with half going up and the other half horizontal at about 65 feet. I use a SGC autotuner to match it because the L is also my 80, 40 and 30 Meter antenna.

On the upper half of the band the tuner didn't really like what it was seeing, but a 2200 pf silver mica capacitor, inserted in series between the tuner output and the bottom end of the wire, fixed that. The antenna still tunes up fine on the other bands. I only have seven radials, ranging in length from 25 to 50 feet and the ground (soil) here would be considered "poor."

However, in the ARRL 160M contest I have reached the west coast including VE7, plus the Caribbean and western Europe. I confirmed WAS on 75M SSB in one season. That's with just a hundred watts, from western South Carolina.

Try it, you'll like it.
 
160 Inverted L, Welcome to Winter  
by WW3ZZ on October 31, 2012 Mail this to a friend!
Nice article..I'm using an Alpha Dela DX-A antenna on 160. It works very well and doesn't require alot of space. I'm also in the process of building a loop antenna for 80 meters. I hope to come up with a design so I can use it on 160 meters as well. Your article is a very good one because it is a limited space antenna and I hear so many people cry about not able to work that band because of available space. A good ham operator always finds a way. Appliance operators just cry.
 
160 Inverted L, Welcome to Winter  
by W5DQ on October 31, 2012 Mail this to a friend!
Good article however I am only short 2 elements of the design ..... namely a pair of 60' trees. Closest tree to me is about 300 feet across the road and in my neighbor's front yard. I somehow think that even though he is not combative towards ham radio and antennas, he (and the county road crews) probably would not take kindly to me stringing wire across a public road and into his yard :) I personally have no issues doing it and even have the wire to do so but ......

I recently setup a loaded 160M sloper off of my 40 foot tower using a Force 12 C3S as the top hat. While this isn't a 3 element monster 160M yagi, it does at least afford me some activity on 160M. This, in conjunction with my modified Hustler 6BTV vertical top loaded with a DX Engineering Hot Rodz 6 foot cap hat and the 80M Super Resonantor coil, let me put a signal on 160M and it appears to be doing fairly well as I have lots of US/Canada contacts as well as a few into the Carribean area over the last couple of winters. I hope to add a few more DX this winter.

Gene W5DQ
 
160 Inverted L, Welcome to Winter  
by N8XI on November 1, 2012 Mail this to a friend!
In 1997 I put up a coax fed 80M Inverted L, not bad considering I didn't use any radials.
Then in 2006 I put up an Inv L fed with 450 ohm twinlead.
Total length 35' Vertical 90' Horizontal to 15' high at the far end.
I use 2 sets of radials. One pair 65' long.
The other pair (I don't know how long) are connected to our cyclone fence, at the far end, that runs for miles throughout the neighborhood.
I had 13 entities on 160M using prior antennas but this antenna 'plays' on all bands(except 80M CW)and in 3 years picked up my 160M DXCC cert in 2009.

73, Rick - N8XI
 
RE: 160 Inverted L, Welcome to Winter  
by KC2WI on November 1, 2012 Mail this to a friend!
I put up a mostly horizontal end fed wire about 120' long using available supports. Can hardly call it an invrted L. Basically threw it over the top of a carabapple tree near the house then to a branch at the far end of the yard. The wire exits out a window, slopes up about 15 feet over the tree and then across the yard. Counterpoise is just under the grass out of necessity and was made out a a convenient handy piece of wire about 100' long. If I had it elevated just above head level it would only be 15 feet below the antenna. The wires are attached directly to the back of my transmatch which is conveniently near the window. Resonant about 1950 but the internal tuner in my 746pro will match it anywhere on 160M. Far from a perfect system but it gets me on the air.
 
160 Inverted L, Welcome to Winter  
by K4IA on November 2, 2012 Mail this to a friend!
Try feeding it at the top - up there in the middle of the antenna at the top of the left hand tree. Run one side of the antenna with a horizontal wire and then down vertically (or sloped). On the other side of the antenna, you have a vertical wire followed by a horizontal one.

You raise the feed point which improves the radiation. You also eliminate the need for radials.
 
RE: 160 Inverted L, Welcome to Winter  
by N8TI on November 2, 2012 Mail this to a friend!
This antenna works well on all bands with the raised radials. Oh, the quad will work better on the upper bands and a dipole will work as well or better with stations broadside to you, but this antenna will do it all and 99% of the time it will be all you need unless you really chase the rare DX. If I were building a station today, I would not spend the money on a tower and expensive antenna. I would go with this antenna and use a tuner on all bands. My inverted L with three raised radials (2 hung on a 6 foot high plastic fence and the third strung through a line of evergreens), works very well. Of course I do use my tower for a support, but I could have used any one of several available trees. This is a very inexpensive antenna that just works well on ALL bands. I relied on this original article to build my antenna. Thanks.

Joe N8TI
 
RE: 160 Inverted L, Welcome to Winter  
by W4VR on November 4, 2012 Mail this to a friend!
As you know Bob,I've been using inverted L's for decades. My inverted L's are 3/8 wave long with 35-50 ground radials. I use 3/8 wave to get the max current lobe up the wire a bit and as a consequence reduce the current at the feedpoint which translates into less power going into the ground system (increased efficiency in other words).
 
RE: 160 Inverted L, Welcome to Winter  
by W4VKU on November 4, 2012 Mail this to a friend!
Finally i was able to get the second 80m L tuned.
I have a single rope up the tree for the L. The 160m
L was already up and tuned. When i later decided to
add the 80m L, the 2 wires were interacting. I found
that the 2ft separation from the ground level to 70ft
did not help.

So i picked up 1/2" conduit gray pvc, cut it into
2 halves and used the 5ft to separate the wires at
the top at 70ft.

Once i did this, i found that i could get the 80m L
at 1.4swr at 3.7Mhz, ie when i did not plug the coax
for the 160m L to the coax switch at the base. The
moment i plug in a piece of free floating coax to
the 160m L, the swr for 80m would jump from 1.4 to
8.1 or so. so i reduced the length of the wire for
the 80m L and got the swr below 3 for 3.7Mhz and
left it at that. Now both the L's are connected to
the remote coax switch. I can run the L's without
the tuner and as i move away from the resonant spot,
i might need to bring the tuner inline at some point.

So within the bounds of the interaction, each of them
work at this point without any other matching at the
based of the verticals/feedpoint.

73s
krish
w4vku
 
160 Inverted L, Welcome to Winter  
by W4PAH on November 5, 2012 Mail this to a friend!
You mention that having a 1:1 current balun is a big must, but then also state that it didn't affect feedline noise. So, which is it? ;)

Also, I'm interested in the design of your current balun (i.e., air wound or on a toroid, how many windings, etc.).

Thanks for the article!
 
RE: 160 Inverted L, Welcome to Winter  
by N4JTE on November 5, 2012 Mail this to a friend!
The balun was placed in the line to help eliminate any coupling to raised radials, the comment about noise not being diminished was just an observation. Standard store bought 1 to 1 current balun.
Tnx
bob
 
160 Inverted L, Welcome to Winter  
by K2JX on November 14, 2012 Mail this to a friend!

I have been using a 66' end fed wire with a 1:1 balun for quite sometime in an urban setting here near NYC.
One side of the balun (10kw rated) is grounded through a standard 5/8" x 8' copper ground rod. The hot end to the antenna wire. I feed the balun with RG-213AU coax from the station tuner through a Poly Phaser lightning arrestor mounted on a 1" x 36" solid copper ground bus in my shack. The grounded side of the balun acts as a static drain reducing much of the man made noise here.

I suppose I should add a counterpoise and I plan on doing just that once all the leaves and brush have gone for the Fall making that task a lot easier. How does my EF wire work, well just great, for 66' of #12 solid [TW insulated] building wire. TW is thermoset weatherproof insulation used in damp locations.

With 66 feet the antenna will load easily on most Amateur bands, besides it fit perfectly on my small lot. I guess it's 30' high, North-South orientation. Using it on 160, well it does work to a small degree, but it's really short electrically to do much damage on Top band. However, as pointed out by others, I CAN get on Top Band with this simple antenna.

73 es tnx de K2JX
 
RE: 160 Inverted L, Welcome to Winter  
by K2UV on November 22, 2012 Mail this to a friend!
I use wire for 160 and 80, and yagis for 40 through 6. I have experimented with virtually every type of wire antenna, even some of my own design. The best practical antenna I came up with for 160/80 was a 3/8 wave inv ell on 160 which, happily, is 3/4 wave on 80. In essence, about 180', as high as you can get it, then as far as you can get the end trying to keep it horizontal, but doing the best you can. I used a 4" diameter ferrite donut wrapped with glass cloth tape, and then even spaced with about 16 turns of uninsulated #10 wire to ground. The antenna connects to the far end of the coil, and I experimentally tapped up up for the feed for the best match. I placed a large air variable in series with the center conductor of the coax, between it and the tap. First I used a vacuum variable and measured the optimum capacitance on both 160 and 80. Then I replaced same with a fixed doorknob cap and the air variable in parallel . The variable gave me enough range to nearly perfectly match on BOTH bands- it stretched the antenna since I work both CW and SSB, but mostly the former. I threw on whatever radials I could muster: the reinforcing wire in my cement patio, the metal sides of my in the ground pool, and the hundreds of feet of coated chicken wire stapled to my post and rail wood fence. Moving up the effective voltage point makes the radials less critical.The direct coil to ground took care of much of the static build up, and tapping that coil enabled me to move the inherently low impedance match to 50 ohms. I remotely tuned the air variable with a low voltage slow , small DC motor I got at a hamfest for 10 bucks. I mounted all that in a rural mailbox. It worked quite well on both bands. I got huge signal reports on 75/80, and easily worked DXCC on 160 in about 2 1/2 years. Alas, that antenna is down, but I plan to resurrect it. The biggest problem with wire between trees is keeping it up-allowing a range of movement from tree to tree with pulleys, weights, bungy cords, whatever. I state all this not expecting anyone to do what I did exactly, but to give you ideas, and maybe some part of my approach will work for you. Have fun! 73, Warren,K2UV
 
160 Inverted L, Welcome to Winter  
by DK5FJ on November 25, 2012 Mail this to a friend!
Thanks for the good article. I tried to load up the horizontal part with a kind of 10m x 1m grid soldered copper wire. It brought down my resonance frequency , and even resticted space in your backyard can give you the chance to put out a good signal on 160. the ground was made by chicken wire. you refer to the antenna site of DJ9RB, Nob.
vy73
Gerd
DK5FJ
DU9SPQ
 
160 Inverted L, Welcome to Winter  
by AA0CW on December 13, 2012 Mail this to a friend!
Having read this, and wanting to get on 160 meters, I installed an Inverted L the other day between a couple of elm trees along the edge of a mesa. Just a ground rod, and a 1:1 balun and using the internal tuner on my Icom 756 Pro III. I was amazed at the amount of activity there is on 160! The first night I worked 8 states from California to Texas in a few hours, with 100 watts, all giving me very nice signal reports. Heard several dx stations too. My swr with the internal tuner is 1:1 across the band, without the tuner it's 1.5:1 around 1.850 and no higher than 2.0 for the rest of the band. I'm probably doing this all wrong, but I'm very happy, and it looks like I'll be staying up late this winter!
 
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