160 meter inverted L radials

Discussion in 'Antennas, Feedlines, Towers & Rotors' started by KG4DYN, Jan 8, 2021.

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  1. KG4DYN

    KG4DYN Ham Member QRZ Page

    Hello everyone,
    I really want to get on 160 meters and have been planning to build an inverted L. I have plenty of tall trees and enough space. My question are whether I should use ground radials or tuned raised radials. I live in the woods so I can install raised radials high enough to be out of the way of people and animals.

    Here are my questions:
    If I do raised radial, how many should I install? Do they need to be straight?
    If I do ground radials, does the length matter? I would have to run them around trees so they would not be straight.

    Any help will be appreciated.
    Doug KG4DYN
     
  2. AK5B

    AK5B Ham Member QRZ Page

    With elevated radials (7' or more for safety) you could actually get by fairly well with two---optimum is around 14 and 4 would be fine. (Don't thank me; it was Rudy Severns, N6LF who discovered this through his exhaustive testing done in the early 1990s).

    Forget ground radials if you can elevate everything; you will be pleased!

    A lot of us will be envying you with all that space.

    73,

    Jeff

    P.S. Two articles worth their weight in inv L gold:

    http://www.on5au.be/Cebik-2/StraighteningOutTheInverted-l.pdf

    http://udel.edu/~mm/ham/randomWire/
     
    Last edited: Jan 8, 2021
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  3. KG4DYN

    KG4DYN Ham Member QRZ Page

    Thank you! This is excellent info. I searched a lot but didn’t find these two.

    Thanks again!
    Doug
    KG4DYN
     
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  4. W1VT

    W1VT Ham Member QRZ Page

    I think it helps if they are symmetrical. If they are current will divide equally between all the radials. But, just do the best you can.
    I use the same radials for 160 as for 80 which means they are really short. But I have 144 countries confirmed on 160!

    I use elevated radials over wet clay and they work well considering the compromises I have living in the suburbs of Hartford CT.
    I can easily walk over to the nearest McDonalds. If I had a modest tower I could see the Golden Arches.

    Zak W1VT
     
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  5. W9JSW

    W9JSW Ham Member QRZ Page

    This is my current experiment. I went with quick elevated radials as the cold weather was close and I wanted something for 160M and I was bringing a new amp online that can do 160M.

    I have a large somewhat square-ish chicken pen. Perhaps 60ft by 100ft. The very large tree is on a S-W 90 degree corner and has a 120ft wire draped across its top and then over to an adjacent tree to the N-NW. I have one 120 ft radial heading N down one side 4ft high, turns 90 degrees to the E and goes down another 60 or so ft. I have another that goes E down the other side of the fence at 4ft high and turns a corner towards N at around 80ft. So pretty much like a open C shape. I have a 60ft radial that bisects the other 2 radials. It is laying on the ground in the chicken pen. The C opens up to the E-NE.

    No ground rod. I have a DXEngineering 1:1 current balun at the base of the tree. 135ft of RG-213 to the shack.

    Here is a pic of a 5 watt WSPR session for around an hour or two just as the band was opening up. These are all stations that heard me. As expected I get most of my contacts towards the East. For a hastily laid out antenna, not bad! I plan to experiment with a better balun and use a 200uH coil to reduce static, as well as something to link the radials to a ground rod, thru some sort of inductor. But this gets me on the band. By the way, the antenna resonates at 1.920MHz with a 1:2 SWR. I will be using it after dark with no kids around so 4ft elevation is fine. I am in the middle of a 40ac farm.

    Lots of noise - maybe S7+. Not many WSPR receives. I installed a Loop-on-Ground that helps that greatly. However it is useable as a RX antenna if the signals are rolling in good.

    erb-on-160M.PNG
     
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  6. WB3BEL

    WB3BEL Ham Member QRZ Page

    If you mainly want to work stations that are in the US and surrounding areas just put up a dipole as high as you can. If you need to, let the ends hang down to make it fit your real estate.

    If you mainly want to concentrate on DX, then the mostly vertical L or T antenna will probably be superior.
    Depending on how serious you are about DXing, then my advice would differ.

    But, you can start out with one antenna and make improvements as you go, if your interests in this band continue.

    For something that will be easy to deploy, then the inverted L with a few elevated radials will get you on the band with minimal effort.
    Four elevated radials can make for a reasonably performing system. You can make do with fewer, but you need to be more careful about their deployment and length. Elevated radial systems with just a few radials also need to have excellent decoupling by using a very good choke on the feedline to prevent currents from flowing on the lossy dirt. This is crucial between a fair system and a good performing system.

    The tradeoff, is that for every foot you elevate the radials, you will lose radiating height of the vertical section. I'd not want to put radials below 8ft if there are animals or people who are unaware of their presence. Also they will be more prone to breakage due to wind, falling tree limbs etc. then ones on the ground. They also will likely interact more with nearby antennas including receiving antennas which are really essential for effective DXing.

    For this reason, if you are more interested in serious DXing, I would recommend to put the radials on the ground. As many as you can reasonably achieve. I'd not want any less than 16, and 30 - 60 or more would likely be better. They don't have to be perfectly straight, but try to make them cover as much ground near the base of the antenna as possible. You will get lots of different advice on how long and how many. This depends to some degree on your soil conductivity. It does not hurt to put in more than needed, other than cost and hard work. If possible, make them longer than 50-60 feet. Lots of short ones can work better than a few long ones as referenced in Rudy Severn's papers. You can start with a subset and add them over time if you run out of energy at the start.
     
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  7. W1VT

    W1VT Ham Member QRZ Page

    Trespassing laws vary by state. And your obligations to protect those invited and not invited on your land.

    My radials are at 5 feet, just high enough for me to mow the yard without issue. My Inverted-L is 36 ft high. I know it would work better if it were higher but what is more important is being on the air. Can't work DX without an antenna that loads up.

    Zak W1VT
     
  8. KG4DYN

    KG4DYN Ham Member QRZ Page

    Thank you for the advice! I want to do DX, but also like stateside rag chewing. I need to survey my location again and do some measuring. It will be no problem to get raised radials high enough for safety. I just need to get busy playing with wire.
     
  9. WB5YUZ

    WB5YUZ Ham Member QRZ Page

    If you have been heard in Europe you are doing well.
     
  10. N5CM

    N5CM Ham Member QRZ Page

    I have an elevated 160m inverted L. I shot lines across three tall pine trees that form a triangle. I brought the lines together in the middle and tied a plastic clothes line pulley to them. On the ground under the pulley, I sunk a 4x4 three feet down. The base of the inverted L is 9 feet above ground level (AGL) on the 4x4. I use 3/16" double braided Dacron line through the pulley to support the vertical radiator wire.

    The vertical portion of the 160m radiator is 68 feet with the remainder horizontal. There are 1/4 wave radials fanning out from the base of the vertical radiator. They are not symmetrically distributed. My house is in the way to the north. They are not straight; however, there are no really sharp angles. To support the radials I've used support lines with insulators from low limbs and/or from nails in tree trunks. Height of radials varies from about 9 to 15 feet AGL along their length.

    I'm 100% CW and 100 watts on 160m. So, far in a little over 2 years, I've worked and confirmed all 50 states and 64 DXCC entities.

    My inverted L is a "fan" antenna with a 1/4 wave radiator attached to the feed point for the 160m. The 80m has seven elevated radials. All of the 80m radiator is vertical. Each vertical radiator comes off the base at a slight angle off vertical. The top of the 80m radiator is about 15 feet from the top of the vertical portion of the of the 160m as best I can tell from ground level.

    I have a 1:1 choke at the feed point of the antennas.

    I've been pleased with the performance of the "fan" antenna on both bands. If you've got plenty of tall trees and room, go for it.
     
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