x80 antenna

A few days ago I mentioned that my HF antenna (a Par end-fed) had blown down. Sadly these days I need help with antennas as my ladder skills (even on to a flat garage roof) are probably beyond me safely.

In the garage I have an almost mint x80 antenna fed with a 9:1 un-un. Reports of these vary with some saying they can break in winds. For now, when I have got a suitable support, I shall probably erect one as it should give reasonable performance on the higher HF bands. At the old QTH, albeit higher, it worked quite well.

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

HF antenna

A few weeks ago my HF wire antenna fell down. At some point soon I need to re-erect it or a suitable alternative. There are several possibilities. Unfortunately, since my 2013 stroke I am always giddy on my feet, so even climbing a few feet up a ladder to my flat garage roof is now a real challenge. Darn!

What polarisation for VHF and UHF DX?

Ever since I started in the hobby I was told, "vertical FM for locals and horizontal for SSB/CW". Now, like many things, I have found that so called "experts" are not! My own, albeit limited, experience on 2m and 70cm is, at best, inconclusive. On 70cm FM I have made some great DX QSOs and also on 2m FM with vertical polarisation.  At the same time I have worked some great DX on 2m SSB with horizontal polarisation.

According to Southgate News, someone has done some recent research. It would not surprise me if there was actually little difference! Funny how old wives tales become facts. Don't always believe what so called "experts" have to say.

Many said my own earth-electrode "antennas" in the ground would not work, but these have now been used from ELF-MF successfully and I am pretty sure at least one VLF grabber is now using such a structure. No, experts are often wrong. Always challenge! That is part of the fun of our hobby.

See http://southgatearc.org/news/2019/april/horizontal-versus-vertical-antenna-polarisation-the-debate.htm#.XMVi2PZFy00

This was a talk on the polarisation of 6m signals given to the Reading club. The link worked for me, even though I am not a club member.

https://groups.google.com/forum/m/#!msg/radarc/3mWN6Pc-Buw/D4OQZi8NBAAJ

Tree surgery - 10m antenna still in place

We had our silver birch tree lopped today. This supports the end of my Par 10/20/40m end-fed wire antenna. This wire antenna is not very high and I was expecting to lose this when the tree was done. As it happens all the tree work was above this, so it is still in place.

Antenna choices

In the very near future, I have to get a tree surgeon in to trim my silver birch tree. This is the support for the end of my 35W Par antenna for 10m, 20m and 40m. One possibility is the erection of my x80 vertical. This is in nearly new condition and has a 9:1 unun in the base to bring the SWR down to the sort of SWR that can be matched with most auto-ATUs. The drawback is it is quite "whippy" and blows around in the wind. It has never been used at this QTH.

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

Antenna choices

Homebase-10 Antenna

When the leaves fall, I want to prune my silver birch tree, which is now far too tall. At the moment my Par end-fed covering 10m, 20m and 40m is held up by this tree. At present, I am considering options.

My main HF interest is 10m and one possibility is a rebuild of my Homebase-10 wire halo for 10m.  Via an ATU, the coax to this antenna should match on most HF bands tuned against ground.

Another possibility is my x80 vertical which is in good condition in the garage. This has a 9:1 unun in its base, so a decent match is presented to the rig on most HF bands. Verticals tend to be noisier than horizontals and the x80 can snap in winds.

I could re-erect my Par end-fed.  This is very low, especially for 20m and 40m.

At the moment, the favourite is the Homebase-10.

New Monster Antenna

Southgate News has a piece today about a new dual-band monster antenna from Innovantennas for 4m and 2m. I think if I tried to erect this I would incur the wrath of the neighbours. Perhaps you live on a remote hillside and the nearest neighbour lives 2 miles away!

See http://southgatearc.org/news/2018/august/new-2m-4m-dual-band-yagis-from-innovantennas.htm#.W3w-ZfZFzIU

Dual band antenna

Some years ago, I made this dual band antenna for 10m and 6m. It worked well.

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

10m antenna for the Es season

As we are about to enter the Es (sporadic-E) season in the northern hemisphere, quite a few people will be looking for a quick, simple, effective and low cost antenna for 10m. May I introduce the Homebase-10 antenna?

By scaling the size, it will also work on 6m and 4m too. At the old QTH it was used for many years. You'll be hard pressed to find something as simple as effective. It appeared in Practical Wireless some years ago.

This has been on this blog before, but many will not have seen it I guess.

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

Indoor 160m antenna

At the old QTH I was looking for a 160m antenna so I made this one in the loft. It worked very well. This was several years ago.

Sadly, since then, the local noise level has gradually crept upwards.

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

2m big-wheel antenna

For a couple of years now I have used a big-wheel horizontal omni antenna on 2m. This is the antenna used in the last few weeks on 2m FT8. It has a near omni-directional horizontal pattern, a little bit of gain and, of course, does not need a rotator. It is ideal for my sort of 2m operation.

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

The linked page needs updating and this is on my "to do" list!

70cm Moxon Beam

This has been posted before, but it is to show amateur radio need not be expensive or hard. I built this antenna in minutes and it worked remarkably well.

Moxon beams have a useful gain, a broad main lobe, and they work. They are ideal for portable work. As this example shows they are low cost to make, especially if you scavenge bits.

See https://sites.google.com/site/g3xbmqrp3/antennas/70cm_moxon

Compact 10m beam

If you are after a small beam for 10m you might try this Moxon 2el.

Moxons have useful forward gain, decent F/B ratio, a fairly broad forward pattern and are easy to make. When up in the air, a 2el Moxon on 10m won't look too big.

See http://www.dxzone.com/cgi-bin/dir/jump2.cgi?ID=9325 .

Some years ago I tried a Moxon on 70cms where it worked well.

Ferrite rod antennas on TX

It is some years since I tried this, but I remember being surprised how well this worked. As long as the ferrite is not saturated, a ferrite rod will work on TX. I tried it on WSPR with the antenna just on the shack table. Of course, WSPR works well.

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

Earth-electrode antennas at 472kHz

Some 4 years ago I posted this based on my results at 472kHz:

These were my conclusions in Jan 2013:

1. The earth-electrode antenna at 472kHz (2 earth rods in the soil 15-20m apart fed from the TX output) behaves like an H-field loop transmitting antenna. At the present QTH the spacing is less.
2. It has directivity, with strongest signals in the line of the loop and weakest signals at right angles to it.
3. It works as an effective RX antenna too.
4. In my environment the loop looks like about 50-60 ohms resistive, so a good match to my transverter directly without matching. At this QTH it looks a higher impedance, presumably because the soil and rock are different.
5. The structure works because much of the return current flows deep within the soil and rock beneath the earth-electrode antenna. In my case Rik OR7T calculated that the loop area in the ground is effectively 290m sq with a radiation resistance of 0.017 ohm and a loss resistance of 66 ohms.This is a BIG loop! I think the loop is smaller at this QTH.
6. Performance compared with my 9m high top loaded Marconi antenna averages only around 8dB down, not a bad figure at all, even with the connecting wire on the ground and not elevated at all.
7. Where no other antenna option is available, the earth-electrode antenna is well worth trying both on 472kHz and on 136kHz both for RX and TX. Although it works well here, your geology may be different and results not the same.

InnovAntennas

Via Southgate News, news of a new antenna from InnovAntennas.  I am sure they are very well made and perform well, but to me they are just too expensive!

See http://www.innovantennas.com/ .

Loop on the ground antenna

See The Loop on Ground Antenna - the "LoG".

I was sent this link by a blog reader who has used it very successfully. It is primarily designed as a receive antenna.

472kHz antenna calculator

See http://www.472khz.org/pages/tools/antenna-simulator.php for a very useful tool to estimate the performance of antennas on 472kHz. This tool was produced by Rik ON7YD.  Based on my own limited experience you do not need big ERP at all to have fun with WSPR on the band.

If you know your antenna current you can use it to work out your ERP or EIRP. The tool will show how much power you need to reach the ERP or EIRP limit for the band.

Antenna faulty

It looks like my tri-band Par antenna, which should be a good match on 10m, 20m and 40m is faulty.  It is a good match on 10m, but only on 20m and 40m via the ATU. Tomorrow I shall try loading it up as a long wire tuned against ground via the ATU. Somewhere I have a Sandpiper Poliakov vertical that I should erect. As I recall  this has a 9:1 unun so it matches well on most HF bands via an ATU.

Even soldering on a coax is hard work these days! Oh to be fit.

At the moment I am on 630m WSPR using the earth-electrode "antenna".

Magnetic Loops on HF TX

It is some while since I used a magnetic loop antenna on HF TX, but these antennas work well, if you can accept their very narrow bandwidth. In fact the sharper the tuning, the more efficient it is likely to be. I used a small magnetic loop made with small-bore central heating copper pipe and was amazed how well it worked with WSPR spots from Japan on 20m with the loop in the shack, which was an upstairs bedroom at the time. Ideal applications are where frequent retuning is not needed such as PSK31, JT65 or WSPR. On 10m they can be very efficient. Even on 20m I was very impressed. Bandwidths are usually measured in kilohertz. Losses have to be kept low if they are to be efficient. Even thin wire will work but the antenna will not be as efficient. As a minimum coax cable or copper pipe should be used for the loop. At QRP powers ordinary air-spaced capacitors work fine to bring the loop to resonance. At 100W these may well arc over.

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