antenna types
DESCRIPTION
Antenna Types. WB5CXC. Resonant Antennas. These are antennas that are resonant on the operating frequency. The most common is the dipole and it’s derivatives. 50 ohm coax. 1/2 Wave Dipole. Length in feet = 468/ F (Mhz). Lower Current / Higher Voltage. Higher Current / Lower Voltage. - PowerPoint PPT PresentationTRANSCRIPT
![Page 1: Antenna Types](https://reader035.vdocuments.net/reader035/viewer/2022062407/56812a99550346895d8e4ec5/html5/thumbnails/1.jpg)
Antenna Types
WB5CXC
![Page 2: Antenna Types](https://reader035.vdocuments.net/reader035/viewer/2022062407/56812a99550346895d8e4ec5/html5/thumbnails/2.jpg)
Resonant Antennas
• These are antennas that are resonant on the operating frequency.
• The most common is the dipole and it’s derivatives.
![Page 3: Antenna Types](https://reader035.vdocuments.net/reader035/viewer/2022062407/56812a99550346895d8e4ec5/html5/thumbnails/3.jpg)
1/2 Wave Dipole
Length in feet = 468/ F (Mhz)
50 ohm coax
![Page 4: Antenna Types](https://reader035.vdocuments.net/reader035/viewer/2022062407/56812a99550346895d8e4ec5/html5/thumbnails/4.jpg)
Current on a Dipole
Higher Current / Lower Voltage
Lower Current / Higher Voltage
![Page 5: Antenna Types](https://reader035.vdocuments.net/reader035/viewer/2022062407/56812a99550346895d8e4ec5/html5/thumbnails/5.jpg)
Voltage / Current on Antennas
• The center point of the Dipole is low impedance (50 ohm).
• The ends are High impedance. • The center of the Dipole will have 70 volts
with 100 w. • The end will have an impedance of 10K +
ohm which give it a voltage of 1,000+ volts. • Have good insulators at the end of the
antenna.
![Page 6: Antenna Types](https://reader035.vdocuments.net/reader035/viewer/2022062407/56812a99550346895d8e4ec5/html5/thumbnails/6.jpg)
Inverted Vee Antenna
![Page 7: Antenna Types](https://reader035.vdocuments.net/reader035/viewer/2022062407/56812a99550346895d8e4ec5/html5/thumbnails/7.jpg)
Inverted ‘L’
![Page 8: Antenna Types](https://reader035.vdocuments.net/reader035/viewer/2022062407/56812a99550346895d8e4ec5/html5/thumbnails/8.jpg)
Dipole Antennas
• Most Dipole antenna are single band or two bands. (They can work on Odd harmonics – 3rd.)
• They are a good match to 50 ohm coax.
• They should be at least ¼ wave above the ground or higher. (On 80 and 40 this is usually not the case.)
![Page 9: Antenna Types](https://reader035.vdocuments.net/reader035/viewer/2022062407/56812a99550346895d8e4ec5/html5/thumbnails/9.jpg)
Dipoles Cont’d
• Back in the 60s we made Dipoles with 3 wires.
• The first would be for 80 meters, the second would be for 40 meters, and then the last would be on 10 meters.
• 80 meters would use the 3rd harmonic for 20 meter.
• 40 meters would use the 3rd harmonic for 15 meters.
![Page 10: Antenna Types](https://reader035.vdocuments.net/reader035/viewer/2022062407/56812a99550346895d8e4ec5/html5/thumbnails/10.jpg)
3 Wire Multi-Band Dipole
![Page 11: Antenna Types](https://reader035.vdocuments.net/reader035/viewer/2022062407/56812a99550346895d8e4ec5/html5/thumbnails/11.jpg)
Dipoles Cont’d
• You can make a multi-band antenna by using traps. The highest frequency is the first portion and the lower frequency uses the entire antenna.
• The traps will also shorten the antenna somewhat.
![Page 12: Antenna Types](https://reader035.vdocuments.net/reader035/viewer/2022062407/56812a99550346895d8e4ec5/html5/thumbnails/12.jpg)
10 M
20 M
10M Trap
2 Band Trap Dipole
![Page 13: Antenna Types](https://reader035.vdocuments.net/reader035/viewer/2022062407/56812a99550346895d8e4ec5/html5/thumbnails/13.jpg)
Traps Cont’d
• The Trap is a parallel resonant circuit. At resonance it presents a very high impedance.
• This high impedance acts like an ‘Open’ circuit and disconnects the rest of the antenna.
• Off resonance the impedance is low and acts like a ‘Short’ thus connecting the two parts of the antenna.
![Page 14: Antenna Types](https://reader035.vdocuments.net/reader035/viewer/2022062407/56812a99550346895d8e4ec5/html5/thumbnails/14.jpg)
Trap
= 2 f L 2 f C
1
fXC( ) XL( )
If you reduce the frequency , then the Trap becomes Capacitive !!
![Page 15: Antenna Types](https://reader035.vdocuments.net/reader035/viewer/2022062407/56812a99550346895d8e4ec5/html5/thumbnails/15.jpg)
XLXC =
10 M
20 M
10M Trap
You cut the longest part of the antenna to work on 20M.
XLfr =XC=
With the Trap in the circuit and you lower the frequency it becomes Capacitive and thus reduces the resonant frequency (which effectively makes the antenna shorter).
(The antenna was cut for 14.2 Mhz, but now it tunes to 13.9 Mhz [too Long now]– you have to cut the antenna to make it tune to 14.2 Mhz.)
![Page 16: Antenna Types](https://reader035.vdocuments.net/reader035/viewer/2022062407/56812a99550346895d8e4ec5/html5/thumbnails/16.jpg)
Verticals
• Verticals antenna are usually a variation of the ½ wave dipole. The vertical is only ¼ wave and the ground reflection provides the other half of the dipole.
• Optimum vertical operation depends on a good ground. This is usually made with radials buried in the ground.
![Page 17: Antenna Types](https://reader035.vdocuments.net/reader035/viewer/2022062407/56812a99550346895d8e4ec5/html5/thumbnails/17.jpg)
¼ Wave Vertical
![Page 18: Antenna Types](https://reader035.vdocuments.net/reader035/viewer/2022062407/56812a99550346895d8e4ec5/html5/thumbnails/18.jpg)
Verticals Cont’d
• Traps can be added to verticals to provide multi-band operation.
• There are several advantages of verticals, the main advantage is that it requires less real estate and height.
• The vertical are a true Omni directional antenna and they have a low angle of radiation.
![Page 19: Antenna Types](https://reader035.vdocuments.net/reader035/viewer/2022062407/56812a99550346895d8e4ec5/html5/thumbnails/19.jpg)
Verticals Cont’d
• Trap vertical have a height of 10 – 30 feet.
• One of the newer popular verticals is the 53 foot. This uses no traps and works most bands (best on 80 – 20M). It requires an antenna turner at the base (similar turner as a long wire turner).
![Page 20: Antenna Types](https://reader035.vdocuments.net/reader035/viewer/2022062407/56812a99550346895d8e4ec5/html5/thumbnails/20.jpg)
Vertical Dipoles
• Vertical Dipole antennas is a new concept to amateur radio (within the last 5 years).
• It looks like an ‘H’ turn on it’s side or some call it a double ‘T’.
• It uses capacitance hats to shorten the elements.
• They require less real estate and also have approximately the same gain as a dipole.
![Page 21: Antenna Types](https://reader035.vdocuments.net/reader035/viewer/2022062407/56812a99550346895d8e4ec5/html5/thumbnails/21.jpg)
Sigma 6M Vertical Dipole
36"
20" X 5/8" Tubing20" X 5/8" Tubing
20" X 5/8" Tubing 20" X 5/8" Tubing
60" X 1" Tubing
![Page 22: Antenna Types](https://reader035.vdocuments.net/reader035/viewer/2022062407/56812a99550346895d8e4ec5/html5/thumbnails/22.jpg)
Vertical Dipoles Cont’d
• They mount low to the ground.
• The coax has to come off at ~ 45 degrees.
• They have a low angle of radiation.
• Sigma (Texas Antennas) and Transworld Antennas are two manufacturers of vertical dipoles.
• They also have multi-band vertical dipoles.
![Page 23: Antenna Types](https://reader035.vdocuments.net/reader035/viewer/2022062407/56812a99550346895d8e4ec5/html5/thumbnails/23.jpg)
Non Resonant Antennas
• There are also Non Resonant antennas.
• The Long Wire antenna is a Non Resonant antenna.
• It is multiple wave lengths long. When we think of a Long Wire antenna we think of an wire that is 200+ feet long.
• Tuner is under the antenna and takes a different kind of turner.
![Page 24: Antenna Types](https://reader035.vdocuments.net/reader035/viewer/2022062407/56812a99550346895d8e4ec5/html5/thumbnails/24.jpg)
Tuner
200' +
Long Wire Antenna
![Page 25: Antenna Types](https://reader035.vdocuments.net/reader035/viewer/2022062407/56812a99550346895d8e4ec5/html5/thumbnails/25.jpg)
G5RV Antenna
• G5RV antennas are multi-band antennas.
• They are not a resonant antenna (except maybe on 20M).
• They will work most bands 80 – 10 (not useful on 30, 17, 10M [by some comments])
• They look like a dipole except that on the center insulator it will have 450 ohm ladder line.
![Page 26: Antenna Types](https://reader035.vdocuments.net/reader035/viewer/2022062407/56812a99550346895d8e4ec5/html5/thumbnails/26.jpg)
G5RV Cont’d
• The ladder line has to hang vertical and can not be near anything.
• You need an antenna tuner for this antenna.
• Normal size is 102’ top and 30’ of 450 ladder line – need ~70’ of coax for antenna to perform properly.
![Page 27: Antenna Types](https://reader035.vdocuments.net/reader035/viewer/2022062407/56812a99550346895d8e4ec5/html5/thumbnails/27.jpg)
G5RV Cont’d
• G5RV Jr. is 51’ top and 17’ of 450 ladder line – need 35’ of coax for antenna to perform properly. This antenna is good for 40M and up.
• The ladder line is part of the antenna and radiates.
![Page 28: Antenna Types](https://reader035.vdocuments.net/reader035/viewer/2022062407/56812a99550346895d8e4ec5/html5/thumbnails/28.jpg)
G5RV Antenna
450 ohm ladder line
![Page 29: Antenna Types](https://reader035.vdocuments.net/reader035/viewer/2022062407/56812a99550346895d8e4ec5/html5/thumbnails/29.jpg)
G5RV Cont’d
• There is a lot of FOLK Lore about the G5RV.
• Some swear by it -- others say it is worthless.
• You need to be aware of what it will do and the pitfalls.
• Most of the poor operation is do to bad installations.
![Page 30: Antenna Types](https://reader035.vdocuments.net/reader035/viewer/2022062407/56812a99550346895d8e4ec5/html5/thumbnails/30.jpg)
G5RV Cont’d
• The antenna should be higher than 34’.
• The top of the antenna needs to be inline.
• The ladder line has to hang straight down and not touch anything or be near anything.
• Should have long lengths of coax for it to work properly.
![Page 31: Antenna Types](https://reader035.vdocuments.net/reader035/viewer/2022062407/56812a99550346895d8e4ec5/html5/thumbnails/31.jpg)
Gain Antennas
• Gain antenna use power radiated in unwanted areas and puts it into a more useable pattern.
• On a Dipole a lot of power is goes up in the air, most of us are not talking to planes so this is wasted power. We also are not talking to stations behind us.
• We direct this wasted energy into a more useable direction (in front / and lower).
![Page 32: Antenna Types](https://reader035.vdocuments.net/reader035/viewer/2022062407/56812a99550346895d8e4ec5/html5/thumbnails/32.jpg)
Gain Antennas Cont’d
• The most common Gain antenna is the Yagi.
• Other Gain antennas include the Cubic Quad, Hex Beam, Moxon.
• In the HF bands these antenna can become quite large and you need a rotor to turn them.
![Page 33: Antenna Types](https://reader035.vdocuments.net/reader035/viewer/2022062407/56812a99550346895d8e4ec5/html5/thumbnails/33.jpg)
Yagi Antennas
• A Yagi antennas has 2 or more elements.
• The simplest is a 2 element Yagi – Reflector & Driven Element (Driver)
• The Reflector is the longest element it is ~ 10% longer than the Driver.
• The Driver is where you feed the antenna.
• On multi-element Yagis you added Directors (shorter than the Driven element).
![Page 34: Antenna Types](https://reader035.vdocuments.net/reader035/viewer/2022062407/56812a99550346895d8e4ec5/html5/thumbnails/34.jpg)
3 Element Yagi Antenna
Reflector
Driven Element
Director
Direction of
Radiation
![Page 35: Antenna Types](https://reader035.vdocuments.net/reader035/viewer/2022062407/56812a99550346895d8e4ec5/html5/thumbnails/35.jpg)
Yagi’s Cont’d
• Yagi come in single band or multi-band.
• Probably the most popular is the Tri-Band Beam with traps – 10, 15, 20. (Reduced size)
• Some of the multi-band beams have multiple element and become quite large (and expensive – need big towers and rotators).
![Page 36: Antenna Types](https://reader035.vdocuments.net/reader035/viewer/2022062407/56812a99550346895d8e4ec5/html5/thumbnails/36.jpg)
Moxon Antenna
• A Moxon antenna is a 2 element antenna with bent elements.
• It is smaller than a normal 2 element Yagi.
• It can be built using normal items from a hardware store and can use wire for the elements.
• Spacing and dimensions are critical.
• Use Moxongen.exe for the design.
![Page 37: Antenna Types](https://reader035.vdocuments.net/reader035/viewer/2022062407/56812a99550346895d8e4ec5/html5/thumbnails/37.jpg)
Direction of R
adiationDriven Element
Reflector
Moxon Beam
![Page 38: Antenna Types](https://reader035.vdocuments.net/reader035/viewer/2022062407/56812a99550346895d8e4ec5/html5/thumbnails/38.jpg)
10M Moxon – PVC & Wire
![Page 39: Antenna Types](https://reader035.vdocuments.net/reader035/viewer/2022062407/56812a99550346895d8e4ec5/html5/thumbnails/39.jpg)
Hex Beam
• Hex Beams are another reduced sized beam.
• It used bent elements (wires) and a non-conductive frame.
• Frame is usually fiberglass rods.
• The frame is made with 60 degree angles.
• The name comes from beam configuration – 8 sided (Hex).
![Page 40: Antenna Types](https://reader035.vdocuments.net/reader035/viewer/2022062407/56812a99550346895d8e4ec5/html5/thumbnails/40.jpg)
Hex Beam Cont’d
• Hex Beams are usually multi-band and can have up to 5 bands on one antenna.
• They bend the rods and string the wiring.
• It looks like an upside down umbrella.
• There is a lot of information on the Internet to build your own.
• Commercially manufactured by Traffie Technology and others.
![Page 41: Antenna Types](https://reader035.vdocuments.net/reader035/viewer/2022062407/56812a99550346895d8e4ec5/html5/thumbnails/41.jpg)
Hex Beam
Driven Element
Reflector
Non-Conductive Frame
![Page 42: Antenna Types](https://reader035.vdocuments.net/reader035/viewer/2022062407/56812a99550346895d8e4ec5/html5/thumbnails/42.jpg)
Hex Beam