"Umbrella" Antenna for 80 mtrs and up by N4SPP
An "umbrella antenna" is basically just a vertical monopole antenna that is top-loaded with a large "end-hat". The hat consists of a number of radial wires that slope away, downward from the top of the antenna. These spoke-wires resemble the ribs of an umbrella, hence the name.
https://www.nonstopsystems.com/radio/frank_radio_antenna_Umbrella.htm

80/40m Vertical by EI7BA
I have always admired the Butternut vertical antennae. They are very well built, using good quality "doorknob" capacitors, and nice airwound low-loss coils. Having had an "HF2" for a while, I decided to see if I could make a homebrew "improved"..?? version.
https://www.qsl.net/ei7ba/80&40mVertic.htm

80/75 Meter 4-Square Array by K7EM
This array has been in use since 1989. The SWR from 3.5 to 3.9 is below 1.5:1. The F/R of the array is 20dB average and with some signals even better.
http://www.qsl.net/k7em/4square/4square.html

80m full size 1/4 wave GPA by ON7EQ
I decided to set up temporarily (during winter months) a full size GPA for 80m and check how well this would perform vs. the Butternut. I can report a very good performance on transmit for continental and transcontinental DX-ing.
https://www.qsl.net/on7eq/projects/80m_gpa.htm

80 mtrs Short Base-Loaded Verticals by N4SPP
This page is a collection of short vertical antennas that I built over the years, for the 80 mtr band. With "short" I mean between 3 and 10% of λ. That is a lot shorter than a standard 1/4 λ vertical. Anything less than 75% of full-size is actually a real compromise.
https://www.nonstopsystems.com/radio/frank_radio_antenna_80m_vertical.htm

80 mtrs Short End-Hat-Loaded Verticals by N4SPP
"Loading" is a way to lower the (primary) resonant frequency of an antenna radiator. This technique is typically used in antennas that have radiating elements that are too short for the desired resonance frequency.
https://www.nonstopsystems.com/radio/antenna_80m_vertical-end-loaded.htm

80 mtrs Short Linearly-Loaded Verticals by N4SPP
"Loading" is a way to lower the (primary) resonant frequency of an antenna radiator. This technique is typically used in antennas that have radiating elements that are too short for the desired resonance frequency.
https://www.nonstopsystems.com/radio/antenna_80m_vertical-lin-loaded.htm

80 mtrs Short Mid-Loaded Verticals by N4SPP
Let's take a vertical monopole radiator that is short with respect to the desire operating frequency. To make it resonant at that frequency, some form of loading is required. By the way: resonant operation is not a requirement - it just makes coupling to a feedline easier.
https://www.nonstopsystems.com/radio/antenna_80m_vertical-cntr-loaded.htm

Portable Vertical Antenna for 75m & 40m by VE2AZX
Portable Antenna for 75m et 40m; Low radiation angle for DX; Efficient; Easy to install. Max height: 30 ft.; Easy match to 50 ohms.
http://www.ve2azx.net/technical/PortableVertical.pdf

Self's building of a HF2V, vertical antenna for 40 and 80m by DL7JV
After different attempts with vertical 1/4 Lambda mono band antennas the desire for a vertical multiple antenna was responsible for 40 and 80m with me. However a Groundplane presupposes a good radial net, otherwise it does not work well.
https://www.qsl.net/dl7jv/e.hf2v.htm

Top Fed Linear Loaded 3/4 wave length Vertical for 80 meters by KE4UYP
This is a vertically polarized Phased array. The left Vertical wire is 180 degrees out of phase with the middle and right Vertical wire. At 1/10 wavelength spacing from the right Vertical wire to the left Vertical wire it is producing a End-Fire Bidirectional Pattern,that developes a Gain of 5.9-DBi.
http://ke4uyp.tripod.com/80m_Antenna.html