Microwaves

This is one area of our hobby I have not done much with. 

I once borrowed a 23cm RX converter and did some tests one night with a homemade 4 el yagi in the room. I also, many years ago, made a 10GHz Gunn oscillator. I had the wrong sort of waveguide and, apart from some very short range tests, did not take it further. These days you can buy some very low cost wideband FM modules that all but eliminate the hard microwave bits. See https://www.amazon.co.uk/Aihasd-Wireless-Microwave-microwave-detector/dp/B00VVDFOHO/ref=sr_1_8?crid=3AXH2GP3143S0&dchild=1&keywords=hb100&qid=1621586561&sprefix=hb100%2Caps%2C180&sr=8-8

One of the things that put me off was the test gear.  I know some have fabricated homebrew measuring gear, but I found optical gear much easier to design, build and test.

The above link allows you to buy the HB100 units from Amazon within days for under £5 each. I am sure you will be able to get them cheaper.

Maybe I should have a go at 10GHz wideband FM?

UPDATE 0852z: A very quick look on eBay found these HB100 units on sale for £1.72 each with quite modest postal charges. See https://www.ebay.co.uk/itm/143788841984?hash=item217a7b9c00:g:VPEAAOSwY31a1FE~. If you buy more than 1 they are even cheaper!

UPDATE 1214z:   I have created a 10GHz webpage. See https://sites.google.com/view/g3xbm4/home/vhfuhfmicrowaves/homebrew/10ghz .

 

Microwave Round Table

Many years ago I went along to the microwave round table at Martlesham, Suffolk. It must have been a very long time ago. I see that on the programme for this year are talks about gear for Oscar 100 and how to make a GNUradio based transceiver. My health prevents me going these days. It is too far to drive.

See http://mmrt.homedns.org/

USA Microwave Meeting

11-14 OCTOBER : MICROWAVE UPDATE 2018

Holiday Inn Dayton, Fairborn, Ohio (near Dayton), USA. 

An international conference dedicated to microwave equipment design, construction, and operation. Hosted by The Midwest VHF/UHF Society, go to www.microwaveupdate.org/ for more information.

A list of rallies can be found at http://rsgb.org/main/news/rallies/

New microwave records

Southgate News reports on new microwave distance records in the UK on high microwave bands.

See http://southgatearc.org/news/2017/june/new-122ghz-and-24ghz-uk-distance-records.htm#.WTUZ5LpFzIU .

10GHz made simple

The HB100 Doppler radar modules can be bought for just a few UK pounds on eBay. These are the modern day equivalent of the Gunnplexers of old. A range of 161km has been achieved with one of these at the focus of a dish antenna on wideband FM.

In conjunction with a separate LNB converting down to 600MHz and a wideband FM RX and you have the makings of a low cost 10GHz system. This was recently used by G4HJW to cover a 10km path. I think Bernie was using just the HB100's own antenna. The HB100 is basically a small PCB unit.

At least one UK station is trying to design a stand-alone 10GHz transceiver based on the HB100 module. Watch this space!

Microwave TX and RX modules

I have just seen this site, although I have never used it so cannot say how good the service is.

See http://www.13cm.co.uk/index.php

47GHz Beacon

47GHz beacon reception. I wonder if this person is professionally involved in microwave work? If not, I am very impressed. Lack of access to microwave test gear has always put me off. Optical test gear and optical gear was easy.

New UK record on 241GHz

I guess we do things the hard way "because it is there".  There are far easier ways to communicate over this distance! As  I said before, personally I think 481THz (optical) is much easier than microwaves.

UK distance on 241 GHz improved to 400m in latest tests by G8ACE. Tweeted by @UKGHZ which is the UK microwave group.

See https://twitter.com/UKGHZ/status/74124618582711091 .

241GHz or optical?

Although the world record for DX on the highest microwave band (241GHz) allocated to radio amateurs is measured in several tens of km, the UK record is quite modest.

My own view is 481THz optical is much easier: test gear is trivial and all the gear can be made inexpensively by nearly anyone. Microwave gear is much harder. I know people say you can "do microwaves" with minimum test gear, but I think you will find most who are successful are, or were, in the business professionally and have access to good microwave test gear. With optical gear this is definitely not the case. Before my stroke I built all my optical gear in the back of a garage and I achieved very useful results. Others have achieved far more than me. All you need are a scope, a multimeter and an audio generator. Much of the test gear needed for optical work is freely available software on the internet.

See http://www.microwavers.org/?241ghz.htm .

IARU VHF news

The next WRC, to be held in 2019, could see some threats to some of our microwave bands. I have to confess very little interest in microwaves. I preferred lightwaves as I was able make all my own kit and test gear. Although 10GHz operation is possible without that much test gear, having some decent 10GHz test equipment must help.

At present, the after effects of my stroke have meant very little building, or field work, has been possible. I sincerely hope that things will get better next year.

See http://www.iaru-r1.org/images/VHF/newsletters/Newsletter_68.pdf

Kent Electronics Antennas

Sam Jewell G4DDK's blog recently mentioned http://www.wa5vjb.com/index.html which has some excellent PCB antennas mainly for microwave bands. If I was serious about microwaves I think I'd be buying some antennas from Texas!

Presentation on CW and other weak signal modes

Andy Talbot G4JNT has put an interesting presentation about weak signal modes onto his website. He gave this talk at a recent Microwave Round Table. See http://g4jnt.com/MartleSham.htm. It is exploring how we can push the boundaries further when working with very weak signals.

Backscatter - microwave compendium

Last week G4BAO showed me a copy of a new book running to nearly 400 pages called "Backscatter" which has been created from articles previously published in the microwave newsletter "Scatterpoint". The book is available for £14 and, if you are into microwaves from 1.3GHz upwards this is a very useful reference book.

It was fascinating to read about something called rainscatter which allows 10GHz stations to work each other by scattering signals off rain clouds/drops up to distances of 600-700kms. This mode allows narrowband uWave stations to work great distances, even from less than perfect home locations. Small 45cm dishes and about 1W RF seems all that is required at 10GHz to use this mode, which works even with NBFM. Signals sound like aurora as they get spread by the scattering process.

I can't see myself getting on 10GHz in a hurry but I can understand the fascination with such intriguing propagation modes to be explored.