Martin's Site
  • Home
  • Ham Radio - K0BXB
    • Logging Contacts
    • The Shack
    • Operating Modes >
      • WSJT-X/FT8
      • DMR
      • D-STAR
      • Ultra Portable PSK/Digital
    • Antennas >
      • Comparing Antennas
      • The Artifically intelligent Antenna
      • Magnet Loop >
        • Mag Loop Overview
      • Portable Antennas >
        • 2 Meter Portable J-pole
        • Five Portable Antennas
        • End Fed Antennas >
          • End Fed Half Wave Antenna >
            • EFHW Summary
          • 29/35 foot end fed wire >
            • Balun or no Balun
          • 51 Foot End Fed Wire
          • 84 Foot End Fed Multi-band Antenna
        • Vertical Antennas >
          • Nine Foot Portable Vertical
          • Short Verticals >
            • DIY 40m -10m Short Vertical Antenna
            • QRPGuys DS1 40m -10m Antenna
            • Pac 12 Portable Vertical Antenna
            • Spiral Wound Vertical
          • 1/4 wavel 20 meter Veritcal >
            • DIY 6 Band Vertical
            • Make a KW4JM vertical
          • QRPGuys 3 Band Vertical
          • Silver Bullet 1000 TIA
          • Portable 17 ft. wire vertical
        • Other Portable Antenna Options
      • Dipoles/Inverted VEEs >
        • Off Center Fed Dipole OCD
        • Comparing the Trap vs. Fan Inverted Vee
        • Link Inverted Vee
        • Trap Antennas >
          • 20 & 40 meter trap dipole qrpkits
          • 40/20 Meter Trap-Inverted Vee
          • 17/20/30/40 Trap Inverted Vee
        • 40/20 Fan-Inverted Vee
        • 40 Meter Inverted Vee
        • G5RV
      • Base Station and General Antennas >
        • G5RV
      • Portable Masts
      • Antenna Test Gear >
        • NanoVNA
        • X5105 Antenna Analyzer
        • Field Strength Meter
    • Radios >
      • IC-705
      • IC-7300
      • XIEGU G90 >
        • G90 Go Kit
      • X5105 >
        • x5105 Go Kit
        • QRP (x5105) Statistics
        • Repairing Mic Cord
      • QRPLabs QCX Transceiver
      • Ten-Tec R4020 QRP Transceiver
    • Portable HF.... >
      • Pedestrian Mobile >
        • Ped Mobile Considerations
      • POTA - Parks On The Air >
        • Thots on POTA Activations
        • My Ideal POTA Kit
        • POTA - Lizard Mound State Park k-9704
        • POTA k-3383 Bald Mtn State Rec Area
        • POTA k-2314 Pine Lake State Park
        • POTA K-4429 Coronado National Forest
        • POTA K-4491 Superior Nat. Forest
        • POTA K-1440 Big Foot
        • POTA K-4265 Bong
        • POTA K-1437 Aztalan State Park
        • POTA - Ice Age Scenic trail K-4238
      • Ham Radio Field Days >
        • 2021 Field Day
        • 2021 Winter Field Day
        • 2020 Field Day
        • 2020 Winter Field Day-
        • 2019 Field Day
        • 2018 Field Day
        • 2016 Field Day
        • 2015 Field Day
      • 2020 Portable Ops
      • Thoughts on Portable Operating
      • Thoughts on Operating QRP/Portable
      • Portable Power
      • Portable CW Keys
      • Tuner/Matchbox >
        • ELECRAFT T1
        • Tuna Tunah II
        • EMTECH ZM-2 ATU
    • Going Mobile HF & VHF >
      • 2020 Mobile Installation
      • 2015 Re-install the Mobile
    • Miscellaneous Ham Radio Topics >
      • Baluns, Ununs, Etc.
      • Keeping wires and ropes untangled
      • Helping Others
      • Things Happen
  • Backpacking/Camping
    • 2020 Backpacking/Camping Season >
      • 2020 Oct Boundary Waters Trip
      • July 2020 Koehler-Andrea St. Park Birthday Camping Trip
    • 2019 Backpacking/Camping Season >
      • September 2019 High Sierra Camp Loop
      • August 2019
      • June 2019 Boundary Waters
    • 2018 Backpacking/Camping Season >
      • Oct 2018 Boundary waters
      • August 4-5, 2018 Wisconsin River Canoe Trip
      • July 16-18 Devil's Lake Birthday Campout
      • June 28-30, 2018 Backpacking/Camping
      • June 2018 ARRL Field Day Camput
      • April 2017 Ice Age National Scenic Trail
    • 2017 Backpacking/Camping Season >
      • July 2017 Camping at Timber-Lee Christian Campground
      • Cancelled Ice Age Trail Backpacking Trip
      • June 2017 Hiking/Backpacking/Camping >
        • Cave of the Mounds and Blue Mounds State Park
      • May 2017 Backpacking/Hiking/Camping >
        • May 19 Ottawa Lakes Campground
        • May 4-7 2017 Porkies Backpacking Trip >
          • Porkies Backpack Trip Day 1
          • Porkies Backpack Trip Day 2
          • Porkies Backpack Trip Day 3
          • Porkies Backpack Trip Day 4
      • April 2017 Backpacking/Camping/Hiking
      • March 2017 Hiking/Camping More Preparations
      • Feb 2017 Hiking/Camping
    • 2016 Hiking/Backpacking/Camping Season >
      • December 2016 Hiking/Camping
      • November 2016 Hiking/Camping
      • Oct 2016 Boundary Waters Canoe Area Trip
      • August 2016 Camping
      • July 2016 Hiking/Camping/Backpacking
      • June 2016 Hiking/Backpacking/Camping
      • May 2016
      • April 2016
    • Shelters >
      • Tents >
        • Reparing Tent Poles
      • Hammocks >
        • Hammock Stand >
          • Portable Hammock Stand
        • SnakeSkins or Sleeves vs. Stuff Sacks
        • Hammock Suspension
        • Keeping Warm in a Hammock >
          • Lite Top Quilt or Bag Liner
          • DIY Under Quilt
    • Glacier National Park 2015
    • Training for Glacier National Park Backpacking Trip
    • Backpacking Stoves >
      • Trangia 27-3 UL Stove >
        • Cooking with Trangia
        • ALOCS Trangia Look Alike Burner
      • Fancee Feest Stove >
        • Fancee Feest & Stanley Cook Pot
        • Another Cat Food Can Stove
      • DIY Alcohol Stove
      • DIY Igniter for Alcohol Stoves
      • Lexada Wood-Gas Stove
      • Wood Burning Backpack Stoves >
        • Emberlit Fireant
      • Gas Cannister Stoves
    • Backpacking Food >
      • Cowboy Coffee
      • Santa Fe Cheesy Beans and Rice
      • Healthy Instant Oatmeal Packets
      • Bacon Ranch Chicken Wrap
    • Other Gear
  • Adventures
    • 50th Anniversary In Alaska >
      • Day 1 Sites in Fairbanks
      • Day 2 Morning River Boat Cruise
      • Day 2 Afternoon travel to Denali
      • Day 3 Denali History Bus Tour >
        • McKinley Wilderness Princess Lodge Photos
      • Day 4 Coach ride to Anchorage/Whittier
      • Day 5 Ship Cruise at Yakutat Bay and Hubbard Glacier >
        • Photos of Yakutat Bay
      • Day 6 Galcier Bay
  • RC Planes
    • 2019 Flying Season
    • 2018 Flying Season
    • 2017 Flying Season
    • 2016 Flying Season
    • 2015 Flying Season
    • Great Planes Escapade - .40 size
    • T-6 Texan
    • Cessna 170
    • Fokker V.23 WWI Combat Sport Scale Plane
    • Great Planes PT-40 Trainer
    • Great Planes Combat Spitfire
    • Hobbico TWINSTAR
    • Other Planes >
      • Flite-Test FT-Cruiser
      • Micro Fokker Eindecker by Dave Robelen
    • Things I've learned....
  • About
    • July 12, 2017 Flood
  • Other....
    • Remembering Charles & Eva >
      • Feist Family Photos
  • KW4JM Contact Log

Comparing  40/20 Meter Fan Inverted Vee and 40/20 Meter Trapped Inverted Vee

On-Air Comparison

2018-06-27 This past weekend my friend Gary (KD9HKI) and I (K0BXB) did Field Day at the flying field of our local RC Plane Flying Club. Gary used the 40/20 meter Fan Style Inverted Vee and I used the 40/20 meter Trap Style Inverted Vee. He worked PSK-31 using about 25 watts and I worked mostly CW but four with SSB, using 5 watts. He logged 40 contacts and I logged 32 contacts. Most of his were on 20 meters and most of mine were in 40 meters. He had a manual tuner but said it required very little adjustment. I did not have a tuner but still was able to work all across the band. My FT-817nd reduced its power a little in the phone portion of the 20 meter band due to the increased SWR but I still made one SSB contact there.

Conclusion

We had no other antennas to compare with on-site, but my conclusion is that these antennas work well and are comparable with each other. Given how comparable their test specs are (see below) and their on-air performance I'd generally choose the trap style version simply because it is somewhat easier to set up given it only has two legs. That is, if I were operating QRP. The Pico Traps, according to the SOTABEAMS website are limited to ten watts. They do have versions for up to 100 watts.

SWR Comparison

2018-06-8  This SWR comparison is based on my own experimentation with a home brew 40/20 meter Fan Style Inverted Vee and a home brew 40/20 meter Trap Style Inverted Vee. I built them as similar as I could given what was at hand. My primary motivation is to have an antenna for Field Day June 23-24. I want the entire QRP station to be lightweight, simple to transport and deploy and not be dependent on trees. My tests in the back yard have convinced me that either antenna will work.
The center insulator/connector for both antennas was mounted 16-1/2 feet above ground atop a  Shakespeare TSP20 Six-Piece Wonderpole with the top section removed.   The feed line for both was 25 feet of RG-174 coax. An MFJ Model MFJ-259B HF/VHF SWR Analyzer was used for all measurements.
Picture
The 20 meter legs of the fan inverted vee are each 16 ft. 8 in. long. For the trap antenna, the 20 meter portion from the center insulator to the trap was 15 ft. 5 in. The additional 40 meter extension from the trap to the end was 14 ft. 5 in. Total leg length is 29 ft. 9 in.
Picture
The 40 meter legs of the fan dipole are each 31 ft, 3 in. long. The 40 meter legs for the trap inverted vee are each 29 ft. 9 in. which included both the 20 meter length of 15 ft. 5 in. and the 40 meter extension of 14 ft. 5 in.

Observations

For some reason the bandwidth of the 20 meter trap antenna is a bit less than for the fan antenna. Further, the SWR curve is a bit flatter for the fan antenna on both bands.
With only two legs to deal with the trap version is simpler to deploy than the fan version which has four legs.
The trap version seemed to involve more fiddling around to get it right than the fan version. That may be just me and how I approached each than an actual fact!
I found the Pico Traps from SOTABEAMS easy to build but less easy to actually attach the antenna wire. The holes provided in the small PC board on which they are built are too small for most wire one might use. Also, getting the wire lengths right involves considerable adding and taking away wire and I don't think the small plated holes and traces would last long when doing that. So I actually fabricated some loops of solid copper wire to which I then attached the actual antenna wire.
Picture
Assembled Pico Trap
Picture
Pico Trap with my wire loops for attaching to the antenna element.
The way to assemble and tune a trap antenna seems to be to first do the shorter legs, 20 meter elements in this case, without the traps or next band (40 meter) extensions attached. When you have the shorter elements tuned the way you want them, add the traps and extension and tune the longer elements. You will have to go back and change the shorter elements some but that will be relatively little and you'll get a good overall result. As everyone warns, it will take some fiddling around!
I really like the Shakespeare TSP20 Six-Piece Wonderpole for the center support. It is light weight and easy to erect and take down. I removed the top section which reduces it's height from 20 ft. to about 16-1/2 ft. I found a small rubber grommet that fit snuggly on the tip of the remaining section which I embedded in the little PC board center insulator I made and so makes it really easy to attach the antenna.
I was concerned about rain. The center insulator on both antennas is very exposed and the BNC coax connector is facing upward so water will likely run right into it and cause a problem. Further the top end of the mast is open to collect water too. So I fabricated from clear plastic sheet a cover for it. It is held in place by tie wraps on each leg of the antenna. For the trap version I did something similar to cover the traps.
Picture
Plastic cover for center insulator. Functions sort of like a rain poncho!
Picture
Plastic cover for traps. Only the top end is closed so it can block water running down the antenna.
Finally, having access to an antenna analyzer really helps with the whole process. Thankfully my neighbor Jerry N9AC loaned me his MFJ-259B. I would likely have given up without that. Using my FT-817nd and my MFJ-204B would have worked but would have taken a lot longer. The MFJ-259B allowed me to fairly quickly determine the antenna SWR across the entire band and make corrections accordingly. The MFJ-204B will show you the resonant frequency and give a reasonable indication of the SWR at that point and that is about all. I'm somewhat of a computer nut also and used LibreOffice Calc to record and plot my readings.
Proudly powered by Weebly