Antenna Types

Resonant Antennas

Radio antennas have a bandwidth over which they can operate effectively; even wideband antennas. Many antennas operate in a resonant mode and this gives them a relatively narrow bandwidth over which they are able to provide excellent performance.

Antenna resonance and bandwidth are two properties for antennas that are closely linked.

Whether the radio antenna is used for broadcasting, cellular, amateur radio, or any other application, the performance of the antenna is very important. So the antenna resonant frequency and the antenna bandwidth are also of great importance.

Resonant antennas are resonant on the operating frequency. The most common type of resonant antenna is the dipole and it’s many derivatives.

The center point of the Dipole is low impedance (50 ohm). The ends are High impedance.

The center of the Dipole will have about 70 volts with 100 watts of transmitted power.

The end will have an impedance of 10K, which can give it a voltage of 1,000+ volts. That’s why we have good insulators at the end of the antenna and keep it away from other objects like trees, branches. Buildings Etc.

Dipole Antennas

Most true Dipole antenna are single band but they can often work on two bands since they would work on the odd 3rd harmonics. An example would be a single wire 80m dipole will also tune on 20m as that is the 3rd harmonic of 80m.

The most common dipole would be equal lengths of wire strung horizontally in air with the feed point at the center, the center is where there is a good match to 50 ohm coax.

At the ends of the wire on each end must be a good insulator, this insulates the end of the antenna and the length of rope that would tie that end of the antenna to a secure point like a mast, tree, or corner of your roof. This length of rope and the insulator at the end of the antenna wire also create a space between the end of the antenna and any other objects that might affect the antennas performance.

For optimum dipole antenna performance you don’t just need the length of the antenna to string up in your yard, but you also need some additional space at each end for the insulator and the rope to tied it up and truly isolate the end of the antenna from other structures. A good installation of a horizontal dipole will have that extra space at the end, and it will also be mounted so no one will be able to accidentally touch or come in contact with any part of the antenna when it’s transmitting.

Dipoles should be at least ¼ wave above the ground or higher. With the exception being on 80m and 40m bands where this is usually not required. So if we’re not worried about the exact height for 80m and 40m, then 20m would be the next popular HF bands where your dipole should be at least ¼ of that off the ground. ¼ of 20m would be 5 meters or 16 ½ feet off the ground. So any height over 16-17 feet should be sufficient for the mounting of a horizontal dipole, but generally the higher the better.

Strung up in the air the wire from an 80m dipole would be 120ft from end to end with additional space at the ends for the insulator and rope.

A popular example of a multi-band dipole can be built with 3 wires all connected at the center feedpoint and fanned out at the ends so they don’t contact each other. When building these fanned dipoles on your own it’s common to use smaller diameter PVC pipe in various lengths to create the fan along the length of the wires so they stay in place, and remain separated from the other wires. The top wire is the longest length wire for the lowest band, and the smaller wires hang below it reducing in length one after the other.

The first and top most wire would be cut for 80 meters, the second wire would be for 40 meters, and then the last would be on 10 meters.

The 80 meter wire would also use it’s 3rd harmonic for 20 meters. And the 40 meter wire would use it’s 3rd harmonic for 15 meters.

With the 3 wires properly tuned this one fanned dipole design would be useful on 80 / 40 / 20 / 15 / and 10m.



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.

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.

While traps provide an effective compromised solution to a shorter antenna design, it’s often manufactured antennas that use traps. Hams who build their own antennas on the cheap will often avoid the complexity of traps and just build full length antennas without the use of traps.



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 very good ground. This is usually made with radials buried in the ground or lawn.

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 less height.

The vertical are a true Omni directional antenna and they have a low angle of radiation.

Trapped vertical have a common height of 10 – 30 feet.

Some of the newer popular verticals are 53 foot tall and use no traps and works most bands (best on 80, 40, and 20M). It will require an antenna turner at the base.


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 a wire that is 200+ feet long.

Tuner is under the antenna and takes a different kind of tuner.


G5RV Antenna

G5RV antennas are multi-band antennas.

They are not a resonant antenna (except maybe on 20M band).

They will work most bands 80 – 10 with a good antenna tuner.

They look like a dipole except that on the center insulator it will have 450 ohm ladder line dropping 30’ vertically towards the ground. The ladder line is part of the antenna and does radiate as well.

The ladder line has to hang vertical and cannot be near anything. So this type of antenna needs to be mounted at least 30’ off the ground at the center point so the ladderline can hang straight down.

You need an antenna tuner for this type of antenna.

Normal size is 102’ top and 30’ of 450 ladder line – need ~70’ of coax for antenna to perform properly.

Earlier I noted that the 80m dipole was 120’ in length, as you can see one of the advantages of the G5RV is that it’s almost 20’ shorter at 102’ end to end.

G5RV Jr. measures out at 51’ across the top and a 17’ drop of 450 ladder line – it need 35’ of coax for antenna to perform properly. This antenna is good for 40M and up.

There is a lot of opinion 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 due to bad installations. The antenna really should be higher than 34’. The top of the antenna needs to be as level and straight as possible.

The ladder line has to hang straight down and not touch anything or be near anything. And you should have long lengths of coax for it to work properly as previously noted.

What makes the G5RV popular is that it’s a bit shorter than a traditional dipole, and for newcomers interested in a cheap antenna that can operate on multiple HF bands they sell for typically $50 - $100 online.


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 typically talking to stations behind us.

We direct this wasted energy into a more useable direction (in front / and lower down towards the horizon).


The most common Gain antenna is the Yagi. Other Gain antennas include the Cubic Quad, Hex Beam, Moxon.

In the HF bands these antennas can become quite large and you need a rotor to turn them.


Yagi Antennas

A Yagi antennas has 2 or more elements and looks like the old roof mounted TV antennas of our youth. They have a center pole that runs the length of the antenna and attached to that are 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 which are shorter than the Driven element.

Yagi come in single band or multi-band.

Probably the most popular is the Tri-Band Beam with traps for the bands 10, 15, and 20.

Some of the multi-band beams have multiple element and become quite large and expensive needing bigger towers and rotators.


Moxon Antenna

A Moxon antenna is a 2 element antenna with bent elements. It is smaller than a normal 2 element Yagi.

The Moxon antenna or Moxon Rectangle is a simple and mechanically robust two-element parasitic array antenna. It takes its name from the amateur radio operator Les Moxon. The design is rectangular, with roughly half the rectangle being the driven element and the other half being the reflector. It is electrically equivalent to a two element Yagi antenna with bent elements and without directors.

Because of the folded ends, the element lengths are approximately 70% of the equivalent dipole length. The two element design gives modest directivity with a null towards the rear of the antenna yielding a high front to back ratio.

The Moxon antenna is popular with amateur radio enthusiasts for its simplicity of construction.

It can be built using normal items from a hardware store and can use wire for the elements. Spacing and dimensions are critical so there is software available for the for the design.


Hex Beam

Hex Beams are another reduced sized beam. They look very much like the vertical cloth hanging racks that people used to mount in their back yards. They kind of look like an umbrella that was caught by a strong wind and the top was inverted. Instead of fabric covering the umbella wire is strung between the support arms.

The Hex Beam uses bent elements (wires) and a non-conductive frame.

The Frame is usually fiberglass rods.

The frame is made with 60 degree angles.

The name comes from beam configuration an 8 sided (Hex).

Hex Beams are usually multi-band and can have up to 5 bands on one antenna.

They bend the rods and string the wiring.

Like I said it looks like a large upside down umbrella.

There is a lot of information on the Internet to build your own.

Commercially manufactured Hex Beams are also very popular. Something to keep in mind is that hex beams are

Hex beams are directional so they need to be tower or roof mounted with a rotor.


So that’s it for the information that I’ve gathered for today.

We’ve covered resonant, non-resonant, and gain antennas.

We’ve covered single band and multiband dipoles, Verticals, G5RV’s, Yagi’s, Moxon’s, and Hex Beams.

Antenna design and theory is a huge part of ham radio and it’s very active in both home brew and retail options for purchase.

This was just a short teaser and I hope you got some good basic information out of it.