In amateur radio circles, the 50MHz band is quite often referred to as the magic band. This is very much the case, but in the microwave bands, the magic band would have to be 10 GHz or the 3cm band. A close second would have to be the 9cm band (3.4 GHz) as it’s free of WiFi noise, but 10 GHz, in my opinion, is an amazing band. This page looks at narrow band 10 GHz Amateur Radio. (SSB)
Unless you have a great location, chances are like most amateur’s who have an interest in microwave, you’ll be going portable quite a bit. Where I live, I’m lucky to overlook Port Philip Bay with views to Melbourne and the western suburbs. I’m also lucky to know a few active amateurs with similar interests living in those western suburbs of Melbourne. Going portable IS a lot of fun.
If you’re considering going down the microwave path, the best advice I can give any aspiring ham is to find a mentor. If you know others who have ventured to the higher bands, then team up with them. Sure it’s possible to do it alone, it’s just a lot more fun building gear with those who have been there before you. Not only is their experience going to exponentially increase your knowledge, you’re going to find a group of like-minded individuals who have test gear, transverters and antenna systems already working, which is so important from a mechanical point of view.
If you love the sound of big numbers when it comes to microwave, you’ll find the frequencies are big but the RF power not so. 250mW is all you need for contacts over hundreds of kilometres. Obstacles such as dirt and buildings are impenetrable for this kind of frequency. Hight, minimal coax runs, and antennas are everything for microwave. The possible exception is EME.
Most transverters are capable of delivering 200 mW (23 dBm) at 10 GHz.
Getting out of the shack and up on a hill is the key to successful microwave contacts. You may be lucky and have a high QTH, but most people don’t. For this reason, when your planning your gear, try and keep it as small and lightweight as possible. That’s not easily the case at times, but if you’re lugging it up a hill you’ll appreciate a lightweight kit. Especially if you’re setting up other bands too.
Pictured here is Robert VK3KRD running portable with 10 GHz at Mt Kororit in Melbourne’s north-west. Rob’s antenna was a 600mm prime focus dish fed with a home brew waveguide and flange.
Rob’s IF radio was a Yaesu FT780R with a 15dB pad between the radio and the transverter. Inside the box is a Kuhne 3rd Generation 3cm transverter with 250mW RF out.
Starting at the microphone, you’ll need an IF radio. Two popular radios currently available and used as an IF transceiver is the Yaesu FT-818 and the Icom IC-705. These two are by no means the only radios you can use. Most transverters can accept a 2m (VHF) or 70cm (UHF) input at less than 5 watts. These are the rig of choice by most microwave operators today, but many have used IC-202s, IC-471s and the Yaesu FT-780R.
The last thing you want to do is destroy a transverter with too much RF as an IF stage. Most transverters use 2 or 3 watts drive as a maximum. Hi-power rigs are a bit of a no-no too as they can suffer from ALC overshoot at the beginning of transmission which can also damage a transverter.
Another feature of the FT-818 and the IC-705 is both radios can be configured as beepers without the use of external hardware. Well, the 818 needs an open 3.5mm jack in the key jack. Details on how to configure the radios are on this site.
Beepers are used to fine-tune signal paths with small antenna adjustments to maximise signal strength.
Both of these radios have internal batteries and both can charge while the radios are powered up. The IC-705 has the added benefit of being able to delay the TX output by up to 30ms. Handy for switching applications. Also, they’re both capable of ground switching TX if needed.
A transverter is an RF device that consists of an upconverter and a downconverter contained in one unit. Transverters are used in conjunction with transceivers to change the range of frequencies over which the transceiver can communicate.
A transverter is the easiest way to get on 10 GHz. There are very few manufacturers of these devices, and the alternative is to build your own if you don’t want to buy.
Building your own may be challenging for those who struggle with SMD components but if you’re interested have a look at Paul Wade’s, WIGHZ’s simple and cheap transverter for 10 GHz. He says his design can be built for around $100 USD.
The image above is a look inside of the Kuhne 10GHz transverter. This is the 4th Generation transverter they’ve made which is now no longer available as the G5 is out. The MKU 10 G5, 3 cm Transverter caters more to the European 10 GHz spectrum demands for the geostationary amateur radio satellite Es’Hail-2.
The image above shows a typical transverter’s IOs. The first SMA connector is the connection port for the IF radio. TX and RX SMAs connect to the coaxial relay or preamps/amps as required. Above the SMAs is where +12v, PTT, +12v TX out and a monitor out is connected. The +12 TX out can be used to energise a coax relay or key a sequencer.
Transverters typically require a UHF or VHF drive of up to 5w. A couple of watts is not uncommon. To switch the antenna from transmit to receive, you’ll need an appropriate coaxial relay. The Kuhne transverters have a +12v TX out @ about 500mA which can be used to engage TX relays, but other systems may require the use of a sequencer.
The Minikits sequencer can be used to control transverters with various components like antenna relays, power amplifier, or receive pre-amplifiers. It is also suitable for sequencing the switching of high power RF amplifiers with a transceiver. It’s a kit that has many small SMD components.
This particular sequencer can handle an input power of 4 watts max. It can also attenuate the TX signal from anywhere between -14dB to -39dB should you need less drive for your transverter.
Below you’ll see the Kuhne transverter and the Minikits sequencer fitted off in a diecast box. What you can’t see is the coax relay underneath the sequencer. Space was a premium in this build as I was using the largest diecast box I could buy, so multilevel design was key.
Now this is where we can open Pandora’s box. so I’m going to keep it simple here and focus on what I’ve been using and my future plans.
Recently I picked up a Phoenix 75cm Ku Offset Dish which I found on eBay for $40. It’s sharp. Very sharp as you may have seen in some of the videos posted recently. Then I was in the right place at the right time – which is a bit how amateur microwave goes – to be fortunate enough to get on the list for one of Paul Wade’s (W1GHz) Dual-band 10 & 24 GHz Feedhorn for Offset Dishes. This was a limited run by Paul, and at the time he said it would be the last. The cost was $185 AUD landed.
The horn is a one-piece machined horn designed for common offset dishes that works very well on both bands. The dual-band feedhorn is intended to feed common offset dishes. All TVRO offset dishes use the same basic geometry, regardless of size or shape. That is why there are so many universal LNBs available, which all have a feedhorn suitable for offset dishes.
Other offset dishes intended for applications including transmitting, like satellite internet, might use a slightly different geometry, but the dual-band feedhorn is probably suitable for these as well.
The common offset dishes require a feed with an illumination angle equivalent to an f/D around 0.6 to 0.7. Efficiency plots for the dual-band feedhorn are shown in Figures 3 and 4, both at the optimum phase center for 24 GHz, 23.6 mm inside the aperture. At 10 GHz, the best f/D is about 0.65, with a calculated efficiency of about 75%.
So pairing Paul’s horn with a garden variety offset dish (OD) was a great option.
Other antenna options include prime focus dishes and homemade horns as Robert VK3KRD uses. Smaller 300mm dishes are much easier to take portable. The images below show Rob’s 10 GHz amateur Radio setup including his 600mm prime focus dish, his station, which includes a Kuhne G3 3cm transverter and the FT-780R IF radio.
Setting up, and learning about how offset dishes work, when you haven’t had much experience with them, can be challenging. The bigger the dish, the smaller the beamwidth, hence the more accuracy needed in aligning your math. There are reasons why experience amateurs use gun sights and micrometers for aligning paths.
According to the manufacturer, this 75cm dish on the Ku-band has gain @ 12.5GHz of 38.5dB. From experience, the beamwidth is no greater than a few degrees horizontally and even less vertically. I initially had the antenna set with the feed arm at the bottom of the installation. Why wouldn’t you when the pay-tv dish on your roof and the installation instructions show that? The reason is satellites are in space and it makes for easy installation. When the station you want to talk to is on the ground, there isn’t enough tilt to align the path without doing some of the work on one leg of the tripod.
The simple solution is to mount the whole dish upside down. Thanks to Gavin, VK3HY for the tip. This is why you need mentors. Now the dish can easily tilt to find the correct elevation for the path. The diagram below shows the maths behind the mount.
The 22 degree offset means that the beam comes off the dish at an offset angle of 22 deg. With the feed at the lower edge, this means that the beam comes off the dish at a 22 deg angle upwards. So, with the feed arm at the bottom, if the front face of the dish reflector itself is vertical, the beam elevation angle is 22 deg upwards. For elevation angles lower than 22 deg the front face of the dish must be tilted forwards and downwards. For elevation angles higher than 22 deg you need to tilt the top edge of the dish backwards. A backward tilt of 68 deg would make the elevation angle 90 deg., (22 + 68 = 90), with the beam going straight upwards.
For very low elevation angles the lower edge of the dish and the back end of the feed support arm may meet up with the mount pole. In such cases, it is necessary to mount the dish upside down with the feed arm at the top. This way you can set zero elevation angle by tipping the front face of the dish 22 deg backwards – which is applicable if you want to use the dish for terrestrial purposes. If the dish is upside down and the front face of the dish reflector itself is vertical, the beam elevation angle is -22 deg (i.e. downwards into the ground). A 30 deg backward tilt of the front face of the dish will give 8 deg beam elevation angle.
I was lucky enough to acquire some 600mm microwave reflectors recently. My plan is to set these up as prime focus antennas with a multiband feeder that I purchased from RF Hamdesign in the Netherlands. They have a good range of dish feeds which may be beneficial to some building a microwave station.
The feed, including the ring mount, landed here in Australia for just under $500. These feeds come in various configurations that I’ve seen in action locally here in VK, with mixed reviews. There’s nothing like trying it out for yourself. Ond of the benefits of using a feed like this is you use one reflector for multiple bands. This means you only have to line up the path once, then simply switch bands as required. Here are the specifications for the RF Hamdesign’s 5 band feed.
5 BAND ring dish feed 23, 13, 9, 6 & 3 cm (1296, 2320, 3400, 5760 & 10368 MHz)
5 separate connector for each band (1*N-Conn / 4* SMA Female)
* 23cm N-Connector
* 13, 9, 6 and 3 cm SMA-connector Female
* 50 ohm
* Power: 23cm 250W / 13cm 100W / 9cm 50W / 6cm 50W / 3cm 20W
* Return loss all bands > 25dB
* F/D: 0.45 – 0.5 (Prime Focus)
This is Peter, VK3APW’s 10 GHz station. Note the ability to fine-tune the path with the use of azimuth and elevation adjustments. He also uses a Kuhne 3cm transverter. The image below is Peter’s RF Hamdesign ring feed which he uses on 23cm to 6cm with an offset fed dish.
SSB Call: 10368.100 MHz
SSB Contest Call: 10368.150 MHz
On February 24 2021, Robert VK3KRD, Neil VK3FS and I (VK3FS) headed out portable to try and work 10 GHz between Mt Kororoit and Mt Martha – a path of 77km with 250mW. Having had much success with the lower microwave frequencies over the past year, we finally managed the first successful 10 GHz contact between us. The path is pretty much clear line of sight, of which 2/3rds is over Port Philip Bay.
This video shows a 10 GHz contact between Rob VK3KRD at home in Glenroy. This is a comparison of his homemade horn and his dish which was quite a revelation. I was portable on Mt Martha. The path is about 68km of which 2/3rds is over water.
This list isn’t a complete list by any stretch of the imagination nor is it an endorsement. I’m adding and subtracting links as I find them. Use these as a starting point. As a general word of advice, anything you find on eBay may not be as good as what you’d probably by from a reputable dealer. Having said that, there are eBay bargains to be had, but do your research and keep in mind you do tend to get what you pay for. Maybe ask in a Facebook group and see if others can share their experiences.
Kuhne make very popular transverters amongst other things. There are products that cover most amateur bands that you need a transverter for. They are pricy and have very expensive shipping. Kuhne is located in Berg, Germany.
The Mini-Kits Microwave Transverter Kits are ideal for getting on the higher microwave bands. They are all available as a basic Kit, or fully optioned including local oscillator, sequencer, RF Amplifier, and hardware etc. Mini-Kits is a South Australian company.
Mini-Circuits design, manufacture, and distribution of RF and microwave components and integrated assemblies. With design, manufacturing and sales locations in over 30 countries, Mini-Circuits offers 27 product lines comprising over 10,000 active models. Mini-Circuits products are used widely in commercial, industrial, and military applications.
The Mini-Kits EME166 Sequencer is very popular. It makes connection to other circuitry much easier due to a single 10 way header connector on the board. The Sequencer can be used to control Transverters with various component like antenna relays, power amplifier, or receive pre-amplifiers. It is also suitable for sequencing the switching of high power RF amplifiers with a transceiver. The circuitry incorporates both DC and RF sensed inputs that can be used to control the switching of the sequencer from RX to TX mode. The sequencer suits Transverters with either a single, or dual I/F connections. The circuitry uses a PIC micro-controller and MosFET switches, and has over voltage and current protection.