Tag Archives: Antennas

Scott’s Self-Supporting Random Wire Antenna System

Many thanks to Scott (KK4Z) who shares the following post from his blog KK4Z.com:

K4SWL+ Antenna

by Scott (KK4Z)

On a recent post on QRPER.com, Teri KO4WFP was at a park in Florida that did not allow wires (or anything else) in their trees. Many POTA activators use End Fed Half Wave antennas which usually require one end in a tree. While it doesn’t happen at all parks, not being able to hoist your antenna could bust an activation.

I realized this may happen to me even though Georgia appears to be pretty lenient when it comes to such matters, I decided to switch to a park friendly antenna. I have been a fan of QRPER.com for quite some time and occasionally Thomas will repost something from my humble blog. That being said, it was K4SWL that got me started using a random wire antenna. My basis for my antenna was his speaker wire antenna which was a 28.5’ vertical antenna with a 17’ counterpoise. I used it a few times in that configuration and then started to modify it. I call this antenna my K4SWL+.

Some of the differences are I use a push-up pole to get the antenna in the air and at the base I use a 9:1 UnUn and a 1:1 Choke to keep RF out of the radio. A random wire antenna can feed RF back into the coax.

The wire is 14 ga. coated flex weave from The Wireman. This was left over wire from some other antenna projects. When I started this project I was using 22-24 ga. coated wire from SOTABeams but realizing there was no need to save weight, used the heavier wire. This allows me to dual purpose the antenna both for FunComm and EmComm. The insulator at the top is 3D printed with my call-sign and the base is U-type lugs. I find these are the best as I do not have to take the nut off of the antenna studs and if pulled hard will come loose instead of damaging the UnUn. I connect the antenna to the top of the push-up pole with a small Nite-eze “S-biner” size 1.

The 9:1 UnUn comes from Palomar Engineering. I have already created a blog post about how to build it and it can be found here: https://kk4z.com/2022/05/28/91-unun-qro/

Part of this blog post was to bring the different components together into one blog post.

The 1:1 Choke can be found here: https://kk4z.com/2022/08/15/lightweight-choke-balun/

I made two different types but I found the second works much better.

The project is pretty easy, the only caveat is to pay attention to what wire goes where. Putting it all together, you need a push-up pole, a Flag holder and maybe a trailer hitch extender. I will provide links below. The Flag Pole holder I used was not available so the link I used is a probable substitute. I have a trailer hitch on both my truck and my camper, When I pull into a campsite I have a choice of which hitch to use to keep my antenna clear from the trees. With the antenna up, I wrap the antenna wire around the push-up pole from tip to base, to prevent the wire from sagging near the tip. I attach the UnUn and choke to the mast with Stretch Velcro Straps. With my antenna up I have park employees drive by me all day along. Most of the time we exchange a friendly wave and occasionally one will stop by for a chat. I have had zero issues with this antenna at any of the parks I have visited.

How does it play? It has pretty much been a main antenna for just about all of my POTA activations. You can go back through my blog post and see what equipment I used with the antenna and the accompanying QSOMap. You do need an antenna tuner with this antenna and I typically use an LDG Z-11 Pro which I’ve had for 15+ years. The antenna tunes up from 80 to 6 meters and I have run the power as high as 65 watts. I normally run 10-35 watts depending on band conditions. I have tried it on 160 meters and while I can get a match, I don’t think much RF is leaving the antenna. I’ve made a few contact with it on 160. If you like to work 160 meters during a POTA activation, I suggest a Chameleon EmComm II with a 60’ antenna and a 50’ counterpoise. I run it as an inverted L with the apex about 20’ up my push-up pole and the end sloping down to something not a tree. Last time I tied it to the lantern stand at the campsite. It worked pretty well and I was able to make contacts on 160.


Click here to view on YouTube.

If you’re looking for an antenna that you can set up almost anywhere, with little or no hassles, take a look at this one. Don’t forget to check out the short video above. 73 — Scott

SSB and CW QRP POTA: Testing my new KM4CFT End-Fed Antenna Kit!

A few weeks ago, I mentioned that Jonathan (KM4CFT) sent me one of his new QRP end-fed half-wave/random wire antenna kits.

When my friend, Alan (W2AEW), caught wind that I planned to buy some 26AWG wire for this build, he sent me a spool of wire from a large reel he’d recently picked up at a hamfest.

What a nice guy! The blue wire is absolutely ideal for portable antennas.

Being the nice guy he is, Alan actually published a video about building Jonathan’s antenna kit on his YouTube channel. I highly recommend watching it!

Before I received the kit, I already knew what type of antenna I’d build: a 30 meter end-fed half-wave (EFHW) linked with a 40 meter extension. This antenna design has been on my mind for some time and Jonathan’s kit was the perfect excuse to build one.

Why a 30M EFHW with a 40M extension? Because a 40M EFHW gives me excellent SWR matches on 40, 20, 15, and 10 meters without needing an ATU.  A 30M EFHW gives me matches 30 and 17 meters.

Thus, with one linked wire antenna, I can cover 40, 30, 20, 17, 15, and 10 meters! That’s a lot of bands!

And since the antenna needs no extra matching, it’ll work with my transceivers that lack an internal ATU.

The Mountain Topper MTR-5B I acquired earlier this year.

In fact, I originally thought about this antenna design to use with my Mountain Topper MTR-5B which covers 40, 30, 20, 17, and 15 meters.

I built this antenna by first trimming it for a 1:1 match on 30 meters including a loop and strain relief to attach the extension.

When I was satisfied with my 30M EFHW, I then made the 40M extension, attached it to the 30M section with 2mm bullet banana connectors, then trimmed the antenna for a 1:1 match on 40M.

I spent the better part of 60 minutes trimming this antenna. I feel like patience really pays off because it’ll set up the antenna for good matches on all of the upper harmonics. Admittedly, I was a bit pressed for time that day, so I only tested this antenna in one configuration (an inverted vee shape) so hadn’t checked the SWR as a sloper or vertical.

My advice is to aim for a 1.3:1 or better match on 30M and 40M–that should be very doable if you wound your transformer correctly.

This was my first attempt at making in-line links, so I wouldn’t consider link my method as a “best practice”–rather, check out K7ULM’s guidance for making in-line links. Continue reading SSB and CW QRP POTA: Testing my new KM4CFT End-Fed Antenna Kit!

GW4OKT’s “Cheap & Cheerful Telescopic SPOTA Antenna”

Many thanks to Keith (GW4OKT) who shares the following guest post:

Cheap & Cheerful Telescopic SPOTA Antenna

Available on eBay for around £45, this 5m whip with a ground spike and counterpoise/radial.

Sold as a QRP antenna, yet in the specs, quote it as ‘able to withstand 300W’, I think I will stay at 5-10W to be honest!

Well, I used it on two POTA activations on the 11th of November, coupled to my KX2 and internal ATU. You can obviously adjust the whip for best match, but I was lazy and left it at full height.

Most QSOs where on 20m and 17m.  The seller quotes that it will tune 20m to 10m and I found this to be correct.  It will also ‘tune’ on 30/40m, but don’t expect decent performance.

This is truly a cheap compromise antenna, but I was surprised how reasonable the build quality was!   As you can see, it doesn’t take up much space, the aluminium ground spike is 10” long including the threaded portion.

The closed up whip is 20.25 “ including the threaded portion.

The ribbon counterpoise is also 5m long and is terminated with an eyelet that attaches to the ground spike threads.  I did consider splitting the ribbon to make a fan pattern, but thought it would be pretty messy to deploy an store, I kept it simple and still achieved good results!

This is a handy standby antenna, or for holiday activations, but bring your tuner along!

72 de GW4OKT

eBay Links:

Jan’s Unun and Balun antenna PCBs

Over on Mastodon, Jan (DG1JAN) posted a few images of a PCB-based antenna project he made available on github. At my request, Jan kindly shared the following information so you can order your own PCBs with design files he has made available.

Jan writes:

Hello Thomas,

I mostly do portable operation (SOTA, COTA, WWFF,…) and I
like playing around with different antennas (EFHW, Linked Dipoles, OCFD…).

So I came up with a little PCB some time ago that you can use as an UnUn (1:49, 1:9) or BalUn (1:1, 1:4) in different configurations.

I’ve put this under CC License so everybody can reuse or modify the Design (PCB Files in Kicad-Format) or order PCB from any Manufacture (e.g. like JLCPCB) by using the Gerber-Zip-File in the repository.

Please have a look to the Project Page on github for details and source-files: https://github.com/DG1JAN/UniBalun

In addition I’ve done some variations of the PCB, e.g. as a
“UnUn only” variant:

Or a “micro” variant of a UnUn:

There are some videos from (mostly) German OMs on YT about the build and usage.

vy 73 de Jan, DG1JAN

Thank you so much for sharing this, Jan! Readers, it’s pretty affordable to use a service like OshPark to order a few of these PCBs. Simply upload the provided Gerber files and they’ll make them for you.

A Portable Oblong Antenna for 2 Meters

Many thanks to Andrew (VK2ZRK) who writes:

Hello Thomas,

The area I live near Canberra in Australia has many SOTA summits that are easily activated on 2m with a HT. That said a good antenna always helps. The 2m oblong antenna is very popular in these parts. It is easy to make, light to carry and packs small. It is horizontally polarised.

This is the second oblong I have built. I gave my dad VK4FASR my first one and have finally built another. I mostly use the bottom of the band for SSB/morse, the middle for APRS on 145.175 and 145.500 for SOTA. The antenna is cut accordingly.


Andrew VK1AD

Peter VK3YE

(Sorry about the lack of Freedom units)

    • 8mm fibreglass tube.
    • 8mm ID kite nocks (both from a kite supply).
    • Double walled glue lined heat shrink.
    • 2200mm Antenna wire – DX Commander in this case.
    • 2mm ‘ZingIt’ dyneema.
    • A BNC to banana adapter.


I cut the tube so the centre to centre distance between the holes in the kite nocks was 360mm as per Andrew VK1AD’s instructions.

With the wire I started with 2200mm and trimmed until I had the best SWR at 145.000 when I lost my nerve and stopped cutting. [See photos below.]

Everything is held together with the glue lined heat shrink.
The top tube includes a little loop made from the ZingIt to suspend the antenna. Total weight is 102g.

The 2mm ZingIt can hold about 200Kg. I hope the pics make sense

Andrew VK2ZRK

Photos with detail

Chameleon MPAS Lite: Using the coax shield as a counterpoise and how this might affect directionality

Many thanks to Dale (N3HXZ) who shares the following guest post:

Portable Operation Using a Vertical Antenna Without a Counterpoise Wire!

by Dale (N3HXZ)

In a previous article that Thomas was kind enough to post, I ran experiments to determine if the counterpoise wire orientation of the Chameleon MPAS LITE antenna system in the vertical configuration in any way shaped the antenna pattern.  The configuration of the antenna is shown below.

The system consists of a 17’ telescoping whip antenna, a matching transformer, a 50’ coax cable with an in-line RF choke, and a counterpoise wire (60’ long, but unwound to only 25’ for use in the vertical configuration).

Subsequent studies I performed have reinforced my earlier conclusions that the positioning of the counterpoise wire in this setup does not appreciably shape the antenna pattern. One of the comments from my post came from Stephan (HB9EA). He commented on the fact that the coax cable is indeed a counterpoise via the coax shield and that in fact my system set-up had two counterpoises.

It was Stephan’s comment which led me to contact Chameleon Antenna to discuss counterpoises with the MPAS LITE antenna in the vertical configuration. I communicated with the Director of Research and Development group at Chameleon and found out some interesting information that I wanted to pass on.

He mentioned that the system can be used with the coax cable acting as the lone counterpoise as long as the coax cable is at least 25’ long, and preferably 50’ long.  The coax should be spread out and not coiled along any portion of its length. It was stated that the counterpoise wire provided with the product should be used with short-length coax cables.

With regards to a counterpoise orientation shaping the propagation direction, he stated that it is generally accepted that using only the coax as a counterpoise tends to have the antenna pattern slightly favor the direction in which the coax is laid out. Adding the counterpoise wire in a direction opposite to the coax would tend to balance out that pattern. Having the coax and counterpoise wire at some angle to each other introduces variables that make it difficult to determine the antenna pattern.

My initial study had the counterpoise wire oriented at an angle to the coax cable.  I mentioned that my initial study showed that orientation of the counterpoise wire did not seem to appreciably shape the antenna pattern, and he agreed. What is unknown is the overall degree to which the coax cable shapes the antenna pattern with or without use of the counterpoise wire.  This is an area I am currently investigating.

Operating the MPAS-LITE vertical configuration with only the coax cable as a counterpoise was an intriguing thought.

To test it out I teamed up with Jim (KJ3D) for a SOTA activation on W3/PT-003 (Seven Springs). We both deployed the MPAS-Lite with only the supplied 50’ coax cable attached. Coax cables were laid out in a straight line. One cable was oriented southeast, the other one oriented east. We operated on 10 Watts in CW mode. The activation successfully worked all bands from 40M to 10M. I operated an Elecraft KX2 and Jim operated a KX3. The internal tuner of both rigs easily obtained a 1:1 match across all bands.

A map of the QSO’s is shown below. Note that despite the coax cables facing to the southeast and east, we easily worked stations in the opposite directions. Hence any minor shaping of the antenna pattern by the coax orientation does not appear to impede successful communication in all directions.

In summary, the MPAS-LITE antenna system in the vertical configuration utilizing the 50’ coax cable with an in-line RF choke as the single counterpoise has been demonstrated to perform well in the field.

For portable operation where fast deployment and simplicity is paramount, using the furnished coax as a counterpoise is a quick and dirty way to get the antenna erected and on the air with reliable communication capability. Eliminating the counterpoise wire allows for quicker set-up and tear-down, and one less thing to put in the backpack!

POTA on Mount Mitchell: The new REZ Ranger 80 and how to use the Over/Under method to coil wire and cable

The REZ Ranger 80 antenna system ships with everything you need, including a nice backpack.

Back in March, I received an email from Mike Giannaccio (W5REZ) the owner of REZ Antenna Systems–he was curious if I’d like to check out his REZ Ranger 80 antenna system.

At the time, my plate was pretty full, so he arranged to send it to me on loan in July.

If you’re not familiar, the Ranger 80 is a portable vertical antenna with a tuning coil at the base that employs a sliding tap for tuning. The Ranger 80 will cover anywhere from 80 – 15 meters without needing any sort of external matching device (like an ATU).

The Ranger 80 Tuning Coil.

If you’re familiar with the Wolf River Coils antenna systems, then you’re familiar with this type of vertical antenna. The difference is that the Ranger 80 is built to what I could only describe as MilSpec standards.

Much of the Ranger 80’s components are CNC machined from premium materials. It sports a Delrin body, black anodized 6061 aluminum, and all stainless steel hardware.

This is not a featherweight antenna: it has the heft to match the caliber of materials used in its construction. It’s not an inexpensive antenna either–it’s currently about $560 US at DX Engineering.

The base of the Ranger 80: note the beautifully CNC-machined holes for the four counterpoises.

The Ranger 80 is also rated for 500W SSB and 250W CW/Digital–in other words, quite a bit more power than I’d ever use in the field, but this design will make activators and field ops happy that like to push some wattage.

I was curious how easy the Ranger 80 would be to deploy and tune, so on Sunday, August 6, 2023, I took it to one of my favorite parks on the planet.

Mount Mitchell State Park (K-2747)

I wasn’t alone on this trip: it was a proper family picnic with my wife, daughters and, of course, Hazel.

The weather was very moody that day–driving up to the park, we watched clouds and mists rise up through the trees like waves crashing on a rocky coast line. Continue reading POTA on Mount Mitchell: The new REZ Ranger 80 and how to use the Over/Under method to coil wire and cable

Barry reviews the RigExpert AA-650 Zoom

Many thanks to Barry (KU3X) for sharing the following review originally posted on his website:

Product Review: RigExpert AA-650 Zoom

by Barry G. Kery, KU3X

If you are building a ham radio station, whether it be a contest station, a station for working DX or just daily rag chewing, this may be the tool you need to help you maximize your signal.

The AA-650 Zoom is a very user friendly antenna analyzer. It is super easy to navigate through the menu to choose what task you want the analyzer to perform.

Let’s start with frequency range. This unit will cover from 100 kHz up to 650 MHz. To get accurate readings, you must enter three factors. You must enter, “Frequency, span and sampling points. “  Here is one of many areas where the AA-650 Zoom shines and that is, “Sampling Points.”

When you sweep a frequency range, whether it’s just the 20 meter band or maybe sweep from 7000 kHz to 30000 kHz, sampling points have a direct impact on the results.

Antenna analyzers do not take a reading one Hertz at a time. They take a reading at numerous points within your sweep range. You can select how many sampling points you want to use. The 650 Zoom gives you 5 options. They are 20, 50, 100, 250 and 500 sampling points.

Let’s say you want to sweep from 7000 kHz to 30000 kHz, like the usable frequency range of a 40 meter off center fed antenna. If you choose to use 50 sampling points, the 650 Zoom will take a reading at every 460 kHz in that range. Once the sweep is finished, the analyzer takes an average and fills in the display with an SWR curve. So it kind of guesses what’s between each point.

Now take that same frequency range but sweep it with 500 sampling points. The 650 Zoom now takes a reading at every 46 kHz.  Remember one thing: the more sampling points you use, the slower the sweep but the higher the accuracy. For single band use, I like to use 100 sampling points.

Most of the time, that’s all you need. But let’s say the antenna you are testing has some quirk at a given frequency. If your sampling points are set too low, your sampling points may not be close enough to detect the problem. So now the analyzer will not know there’s an issue and fills in the display with an average reading.

There are two ways to setup the analyzer for a frequency and range. To the left shows where you can manually enter the center frequency and the span of the sweep. Press the, “Frequency key” on the keypad to access this feature. Within that display, to the far left you will see meter bands. If you press the, “F key” on the keypad, a band will be highlighted. Use the up / down arrow keys on the keypad to select your band of choice. When you let up on the, “F key” the analyzer will program that band with a predetermined span.

The picture on the right shows yet another super easy way to set up the analyzer. To access this screen, press and hold the, “F key” and then press the zero key on the keypad. The rest is easy. Pick a number that corresponds to the band you want to check.

Top picture shows an SWR curve of my 40 meter beam. This reading was taken from my shack. Take note of the bottom of the display. The analyzer lets you know what the minimum SWR is at a given frequency. On the top of graph, the SWR is shown in relation to the pointer.

The top right picture shows the SWR of my 20 meter beam at a given frequency. You may find this feature useful for adjusting a manually operated transmatch or adjusting the tuned inputs of your home brew amplifier. On the bottom of the display, it shows return loss at 14150 kHz.

When you sweep a frequency, you can save the SWR plot in any one of the 99 non-volatile memory slots so you can retrieve them at a later date.

If you want to check more than one frequency at a time, like on a tri band Yagi or an off center fed antenna, the AA-650 lets you pick up to 5 different frequencies to check at one time.

Shown below are return loss figures for a low power 4 to 1 Guanella Current Balun. The balun was designed to be used from 80 to 10 meters. The sweep is from 2 MHz to 30 MHz.

Let’s talk OSL Calibration…

Using Open, Short, Load calibration is a way to cancel out your transmission line so you can take a reading of your antenna like you are attaching the antenna analyzer to the feed point of the antenna. Let’s take a 100 foot length of RG-8X as our coax used for testing antennas. Hook the coax to the 650 Zoom and run OSL Calibration. Once you do that, it’s like the coax is transparent. Continue reading Barry reviews the RigExpert AA-650 Zoom

Barry reviews the PAC-12 portable antenna

Many thanks to Barry (KU3X) for sharing the following guest post originally posted on his website:

Product Review: PAC-12 Portable Multi Band Vertical Antenna

by Barry G. Kery, KU3X


I am always on the hunt for a better mouse trap. Dave, NB3R came across a great multi band vertical antenna for portable operating. It’s a, “ PAC-12 7-50MHz Shortwave Antenna “ found on AliExpress.com.

The PAC-12 antenna is designed to operate on any frequency from 6 meters down to 40 meters.

Numerous manufactures make multi band vertical antennas designed to be used for portable operating. Some have quality issues and others may have performance issues, or both? Any hunk of wire or aluminum will radiate if RF is applied to it, but how much will be radiated is the question.

When it comes to ground mounted vertical antennas, one major factor that effects performance is the ground radial field. The PAC-12 comes with a long ribbon cable that you will have to separate each wire and cut to a quarter wave length per band of operation. There are ten wires within the ribbon cable. The length of the ribbon cable is 18 feet. This is too short for 40 meters but perfect for 20 meters. I made four 35 foot long radials out of some wire I had laying around the shack. This will increase the performance on the 40 meter band as well as making a better match. Spread the radial wires out equally around the base of the antenna.  Since the radials are not elevated, they do not have to be tuned but it does make for a better match.

The antenna comes with a short stake that can be driven into the ground for attaching the ground radial crimp on to and attaching the feed insulator.

The stake is strong enough to support the entire antenna, even on windy days. The feed insulator has an SO-239 for connecting your coax. The feed insulator must be attached to the ground stake correctly. Make sure the writing on the insulator is on top of the SO-239 and the black portion of the insulator is attached to the ground stake.

So what makes this antenna perform better than most other commercially made portable vertical antennas? Answer, “the mast!”

Most manufactures, not all, use a tapped base loading coil to make the antenna resonant on numerous bands.  On a quarter wave antenna, the wire or aluminum closest to the feed point of the antenna is the current portion of the antenna and the current portion does the most radiating. Continue reading Barry reviews the PAC-12 portable antenna

Do I allow antenna wires to touch tree branches during field activations?

Many thanks to Keysrawk on my YouTube channel, who asks:

Do you usually try to use an isolator or do you often let your wires touch branches by just pulling them over? When you deploy 20m EFHWs, for example, do you try to avoid having an end touch a branch and only have the throw line going over the branch? I tried to go through your videos and look but you don’t often mention how far you pull the wire up and possibly over. Thanks!

This is a great question!

Before I answer, I’d like to add a little context:

  1. I am a QRP operator. The maximum amount of power I use in the field is 10 watts, but 99.5% of the time, it’s actually 5 watts or even much less.
  2. I am answering this as a field operator, meaning I’ll be referring to temporary antenna deployments.

That said, the quick answer is no, during park and summit activations, I do not worry about my antenna radiator wire touching tree branches.

I do isolate the end of my wire antennas from tree branches and leaves, but I don’t worry about other parts of the radiator touching.

Also, all of my antenna wire has some sort of jacket–I don’t run bare wire in the field.

More often than not, when I deploy a longer wire antenna–say, a 40M EFHW–I simply use a tree branch to support the apex of the antenna if I deploy it in an inverted vee configuration. Continue reading Do I allow antenna wires to touch tree branches during field activations?