Flower pot antenna

Steve G1KQH recently sent me an email with some useful links on how to make 1/2 wave verticals. I am sharing it with you in case this gives you ideas.

"The latest G4NSJ video pointed me to investigate..

Cheap to make for anything from 28MHz to UHF I guess.. Ideally a starting point is to make one for 2m

Gain 1dB over 1/4 Wave

Details here: 

http://vk2zoi.com/articles/half-wave-flower-pot/

You can even make it Dual band:

http://vk2zoi.com/articles/dual-band-half-wave-flower-pot/

There is even an online calculator:

https://nomonsuhendar.blogspot.com/2020/12/flower-pot-antenna-calculator.html

73's G1KQH"

The tiny indoor loop

This is the inside of my loop antenna used successfully on 20m FT8 to 10m FT8. I am amazed how well it works. 

The wire used for the loop is quite small and I might try much thicker wire. Tuning should be sharper, but efficiency should be higher. My concern is higher Q means higher voltage at the high impedance point. 

Antenna ideas

For many with small gardens or difficult neighbours, antennas can be a problem. The biggest antenna I have ever used is a CB halfwave. I have never used an HF beam. Despite this, I have worked QRP DXCC with 10W SSB. Most  times I have used just a low wire dipole.

One "antenna" I have found useful is the earth-electrode "antenna" in the ground. This has proved very effective on VLF, LF and MF. Only last evening I was copying Italy on it on 630m and the night before there were lots of stateside stations spotted on 160m FT8. An advantage is the XYL and neighbours do know even notice it is there at all! 

Another possibility is to use the coax outer feeding maybe a VHF antenna via an ATU on the HF bands tuned against ground. Such antennas can be quite effective. OK against a beam on a tower this maybe an S-point or 2 down, but for the lack of neighbour hassle is a tall tower and big beam worth the fuss? This is a hobby after all. If you don't work DXCC entity 247 does it really matter? Get a life!!!

See https://sites.google.com/site/g3xbmqrp3/antennas/earth-electrode-antennas .

Indoor loops

One of the great advantages of QRP is in the design of loop antennas for TX. With 100W, the voltage at the high impedance part of the loop can be very high, so that special capacitors are needed with low loss and a very high breakdown voltage. 

With QRP powers, ordinary capacitors may be used. Most times I use an old Wonder Wand Loop for 20m, 17m, 15m, 12m and 10m. My 10m loop, homemade with copper pipe, is sharper and more efficient, but harder to tune.

See https://sites.google.com/site/g3xbmqrp3/antennas/magloop.

Antenna projects

During the next few months I have a couple of antenna projects that need doing. 

Firstly I need to get an antenna for 10m erected. The easiest would be either an dipole or inverted vee. My problem is erecting this, even though it is small. At about 5m overall length this is quite compact.

My second project is to replace the wire back to the shack from the far electrode of my earth-electrode "antenna". This should be straightforward.

Another possibility is an end fed antenna via a 49:1 unun. This should be a low impedance and multiband antenna even without an ATU. With a modest ATU I should be able to get a good match on all HF bands.

Antenna video

A friend, Chris, passed on the link to this old talk and demonstration about antennas. You might find it helpful. 

For some reason, the video did not work, so I hope this link works!

See https://www.youtube.com/watch?v=LEigIMS6bo4

Not an amateur radio tower

I have never had a head for heights! Luckily, this is not one of my amateur antennas!

Magnetic loop on windowsill

After the recent experiments with the Rybakov antenna, I am trying the tiny magnetic loop antenna on the windowsill indoors (see photo). Although it matches on all HF bands, I get some RF feedback on some bands.

On 15m RX it seems to do pretty well.

UPDATE 1347z: On 17m FT8 it works (see logbook and map) with 6 stations spotting my 10W to the magnetic loop so far.

17m FT8 TX with 10W to the tiny magnetic loop

UPDATE  1356z: Just after posting the above I get spotted by WN4N (4339 miles) in Florida on 17m FT8!! Not bad with this tiny magnetic loop and 10W. Also spotted by 5T5PA (3791km) in Mauritania, West Africa on 17m FT8.

UPDATE 1420z: 8 stations in 3 continents  spotting my 10W 17m FT8 TX to the tiny indoor magnetic loop antenna so far today. Quite amazing.

UPDATE 1429z: 111 stations spotted so far today on 17 FT8 RX with the tiny indoor magnetic loop antenna.

UPDATE 1452z: A 2-way QSO with AV4VV (3938 miles) in North Carolina with 10W 17m FT8 to the tiny magnetic loop. I am now beginning to believe anything is possible!

UPDATE 1511z: Quite remarkable the stations spotted so far today on 17m FT8 RX with the tiny loop.

Stations spotted so far today on 17m FT8 RX
with the tiny magnetic loop on the windowsill

UPDATE 1530z: I am wondering if 17m is fading out now? There would appear to be far fewer stations on 17m FT8 RX now.

UPDATE 1735z:  In all, I was spotted 8 times by USA stations on 17m FT8 with the tiny magnetic loop on the windowsill indoors.

Stations spotting my 10W 17m
FT8 with the magnetic loop today

A Rybakov antenna on the bench?

In the garage I have a virtually unused SRC X80 end-fed vertical antenna. This was very briefly erected in about 2011 and has remained unused for years. I took it down as reports said it blew around in high winds and at the time my interest was mainly on 10m for which I had a suitable antenna at that time.

The X80 is a sort of Rybakov antenna. These are end fed antennas fed via a unun transformer so the very high end impedance is transformed into a VSWR less than 3:1 that can usually be matched via the auto-ATUs in most modern HF rigs.

As an experiment, I tried loading up the coax to my 2m big-wheel via this Rybakov transformer. I can get quite a good match on a couple of HF bands (at least) but on some bands the VWSR was so bad that the rig just turned off!

By ear, I think my small indoor magnetic loop is as good!

Antennas

One possibility I have is to erect a BuddyPole or similar multi-band /P antenna in the garden when needed. This cannot be as effective as a larger antenna, but would give me multi-band capability. I imagine on 10m, 12m and 15m they could be quite effective.

Certainly on FT8, they should work. This might solve my antenna erection issues. I could put it out when required and put it away when not needed.

If you have any views, please let me know.

G3XBM shack and antennas

Just over a year ago I made a video showing the shack and antennas in use at that time. My voice is very poor!

Since then, I have made a few changes, but still mostly use FT8. There are other videos on the G3XBM channel, most made when my voice was OK!

10m antenna

Since my Par antenna started giving a very high VSWR, I have been looking for a 10m antenna for the next cycle and for Es. Being considered are CB verticals of various types, wire dipoles and my Homebase-10, which is basically a wire halo. I used the latter at my old QTH very successfully, although I cannot get it as high at this location. Verticals tend to pick up more local noise but are good omnidirectional antennas. Dipoles are not so good off their ends. In all cases I need help with erection, sadly.

There is a video showing the Homebase-10 erected at the old QTH. The video is actually about a 500kHz antenna, but shows the 10m antenna pretty well. There are other videos on the G3XBM channel.

160m antennas

Although my earth-electrode "antenna" in the ground has got me over 1300km on 160m FT8 recently, some may prefer more conventional antennas. I had this problem at the old QTH and came up with this compact indoor vertical in the loft.  It seems pretty effective. It was wound on an old piece of PVC pipe.

See https://sites.google.com/site/g3xbmqrp3/antennas/160m_loft_ant

HF antennas

Some years ago I bought an x80 vertical antenna. These are basically Rybakov vertical antennas. I erected mine briefly at the old QTH, but have not done so here. I would need help with erection, whereas my end-fed I managed to string to a nearby tree on my own. The end-fed is a good match on 10m (my favourite HF band) , where it seems to do quite reasonably on FT8.  So, for now, the x80 is unused.

At the time (2011) the x80 had mixed reviews. Some said the aluminium flexed too much and broke. Being a vertical, it is probably noisier than a horizontal antenna. If you have an auto ATU it is quite an easy way to get on several HF bands. These days I think there are stronger versions around.

See https://sites.google.com/site/g3xbmqrp3/antennas/x80

End fed 10/20/40m antenna re-erected

After being down for all the summer, I have re-erected my 10/20/40m end fed antenna. It broke earlier in the year and I thought some ladder work was needed. I am wobbly on ladders these days. Luckily I could reach the parts that mattered without a ladder and it is now strung to a different tree in the back garden. Getting the wire over the tree was surprisingly hard for me. Years ago this would have been trivial, but not any more.

Although I get a good match on 10m there is a high VSWR on 20m and 40m even with the tuner. At least I am able to WSPR and FT8 again on 10m. Most of the far end (after the 10m choke) is in the tree. To get a decent match on 20m and 40m , I need to choose another end point. It is probably fine on RX on 20m and 40m.

Miracle Antennas

It is some years since I last used my Miracle Whip. In fact, I am not even sure where it is! These days there are commercial alternatives as the original inventor became a SK in 2012. Now, please do not expect miracles from any of these. As I have said many times, a 56 inch whip can only be as good as a 56 inch whip, but with a counterpoise or ground they can work reasonably well on the higher HF bands. In their favour, they are small and convenient.

See https://sites.google.com/site/g3xbmqrp3/antennas/mwhip

Compact 160m loft antenna

This has appeared before but may spark some ideas in some people. At the old QTH (we moved 6 years ago, which seems incredible) I had a need for a simple antenna for 160m. At that time, I had easy access to the loft, so this antenna resulted. It was quite effective.

See https://sites.google.com/site/g3xbmqrp3/antennas/160m_loft_ant

Ferrite rod transmitting antennas

This has been posted before, but results may surprise many.

Perhaps I should repeat these tests with FT8 from this QTH. FT8 is not as good as WSPR with weak signals but it is better than CW.

These tests were done at least 6 years ago and I have not tried since.  It must be used with QRP or the ferrite may saturate.

See https://sites.google.com/site/g3xbmqrp3/antennas/ferrite_tx

2m big-wheel antenna

For many years now my main 2m antenna (and 70cms!) for SSB, CW and digital modes has been a 2m big-wheel omni, sometimes called a clover leaf. This has a little horizontal gain, but is a fixed antenna that does not need a rotator. It well suits my style of operating. I use this for 2m and 70cm UKAC sessions and casual use at other times.

Most days, irrespective of conditions, I spot at least 7 countries on FT8 RX and I am spotted at ranges of 400-500km when I call QRP CQ on FT8. For me, this antenna is perfect. For FM I use the V2000 vertical. At one time I had a hand-rotated small dual band beam, but I find the big wheel better suited.

See https://sites.google.com/site/g3xbmqrp3/antennas/bigwheel

Mending the HF antenna

As long as I can get up the ladder to my flat garage roof, I intend to mend my Par 10/20/40m end-fed antenna next week. This is not the best antenna in the world, but I know how it works. It can handle QRP power levels (actually up to 35W). The wire fatigued at a joint (after nearly 6 years), so it should be easy to fix. We have guests this week, so it can wait. The biggest challenge will be getting on and off the ladder!