Page updated 6th May 2022
40 Meter 4 Square Antenna Specifications
Between posts: 10.5 meters
Antenna height: 10.240 meters
Radial length: 12 meters
Number of radials per antenna: 32
Single antenna ressonance: 7.080 MHz, 1.26:1, 51 Ohm.
RG-11 75 Ohm feed cables: Cut for 7.140 MHz
VSWR readings in shack on 7.100 MHz:
NE 1.31, 50 Ohm
NW 1.15, 50 Ohm
SE 1.24, 56 Ohm
SW 1.36, 52 Ohm
OMNI 1.76, 31 Ohm
HYTOWER HYGAIN VERTICAL INFORMATION
|Number of radials||16||24||36||60||90||120|
|Length in wavelengths||0.1||0.125||0.15||0.2||0.25||0.4|
|1.840 MHz||16.30 Mtrs||20.38 Mtrs||24.46 Mtrs||32.61 Mtrs||40.76 Mtrs||65.22 Mtrs|
|3.600 MHz||8.33 Mtrs||10.42 Mtrs||12.50 Mtrs||16.67 Mtrs||20.83 Mtrs||33.33 Mtrs|
|7.100 MHz||4.23 Mtrs||5.28 Mtrs||6.34 Mtrs||8.45 Mtrs||10.56 Mtrs||16.90 Mtrs|
|14.200 MHz||2.11 Mtrs||2.64 Mtrs||3.17 Mtrs||4.23 Mtrs||5.28 Mtrs||8.45 Mtrs|
|21.150 MHz||1.42 Mtrs||1.77 Mtrs||2.13 Mtrs||2.84 Mtrs||3.55 Mtrs||5.67 Mtrs|
|28.300 MHz||1.06 Mtrs||1.33 Mtrs||1.59 Mtrs||2.12 Mtrs||2.65 Mtrs||4.24 Mtrs|
|Spacing in Degrees||22.5||15||10||6||4||3|
|Total length of wire in Wavelengths||1.6||3||5.4||12||22.5||48|
|Power gain Db due to increased efficiency||3||3.6||4||4.7||5.2||6|
|Feed-point impedance with 1/4 wave radials||52||46||43||40||37||35|
|Radial end buried.||YES||YES||YES||NO||NO||NO|
A 27MHz Ringo has been collecting dust in the shed for years, and after successfully constructing a vertical for 6 meters, it was time to put the Ringo to good use.
The plan is to remove the ring and connect 4 x ¼ wavelength radials for each band. The center of the SO239 connector is connected to the 5.3 meter driven element via a short piece of aluminum. The driven element is already a 1/4 wavelength on 20 meters. A bracket was made from aluminum strip to bolt the radials to and was screwed to the existing earth bracket left over after removal of the ring.
A 50mm x 500mm pipe is hammered into the ground leaving 200mm above the ground for the base of the vertical to slip into. Radials were cut from 2.5mm diameter aluminum wire scavenged from old power line cable. Initially the 10 and 20 meter radials were bolted to the earth bracket. A random length of RG58 coax was run from the antenna to the shack where a dip meter coil was screwed on. One would have thought that 20 meters would have tuned/dipped perfectly being a 1/4 wavelength vertical. But not so. Adjusting the length of the antenna had no real effect on the reading of 18MHz dip.
After several failed attempts on other frequencies, the coax was tested resulting in – yes – a 18MHz dip. (It is interesting to note that the coax had little effect on resonance when the antenna was setup for a 1/4 wavelength on 28MHz, but played havoc when used for other wavelengths and/or bands). A new 27.85 meter length of coax was cut and terminated with PL259 plugs. This cable now dipped on the amateur bands and was duly plugged into the antenna. Hey presto, a perfect VSWR was obtained on 14MHz as expected. The length of coax cut is the only length of cable that is resonant on all HF ham bands. One could cut a single 1/4 wavelength piece to match one band but the aim here was to use all bands with one vertical.
Two radials for 7MHz were now attached and laid out across the ground. (The other two are yet to be cut). 10cm of each end was bent down and pushed into the soil to hold them in place till a proper burial can take place. Further testing confirmed the entire 14MHz band was 1:1 and 1.4:1 on 6 meters. With the aid of an ATU, all other bands were tunable including 80 meters. Yet to add is 2 more radials for 7 MHz, and radials for 21MHz. It will be interesting to see what improvements, if any, take place once they are in place.
The following table was used as a guide for measurements. Radials were cut using the measurements in the 1/4 wavelength column.