Get On 10 GHz For 3 Euros

A frequent complaint you will hear about amateur radio is that it is a chequebook pursuit. Of course you can work the incredible DX if you spend $20k on a high-end radio, big antenna, and associated components. The reality is though that because it’s such a multi-faceted world there are many ways into it of which the operator with the shiny rig is taking only one.

On the commonly used HF and VHF bands at the lower end of the radio spectrum you will definitely find chequebook amateurs of the type described in the previous paragraph. But as you ascend into the microwave bands there are no shiny new radios on the market, so even the well-heeled licensee must plow their own furrow and build their own station.

You might think that this would remain a chequebook operation of a different type, as exotic microwave devices are not always cheap. But in fact these bands have a long history of extremely inexpensive construction, in which skilled design and construction as well as clever re-use of components from satellite TV systems and Doppler radar modules play a part. And it is a project following this path that is our subject today, for [Peter Knol, PA1SDB] has repurposed a modern Doppler radar module as a transmitter for the 10GHz or 3cm amateur band (Google Translate version of Dutch original). The best bit about [Peter]’s project is the price: these modules can be had for only three Euros.

Years ago a Doppler module would have used a Gunn diode in a waveguide cavity and small horn, usually with an adjacent mixer diode for receiving. Its modern equivalent uses a transistor oscillator on a PCB, with a dielectric resonator and a set of patch antennas. There is also a simple receiver on board, but since [Peter] is using a converted ten-Euro satellite LNB for that task, it is redundant.

He takes us through the process of adjusting the module’s frequency before showing us how to mount it at the prime focus of a parabolic antenna. FM modulation comes via a very old-fashioned transformer in the power feed. He then looks at fitting an SMA connector and using it for more advanced antenna set-ups, before experimenting with the attenuating properties of different substances. All in all this is a fascinating read if you are interested in simple microwave construction.

The result is not the most accomplished 10 GHz station in the world, but it performs adequately for its extremely low price given that he’s logged a 32 km contact with it.

Though we cover our fair share of amateur radio stories here at Hackaday it’s fair to say we haven’t seen many in the microwave bands. If however you think we’ve been remiss in this area, may we point you to our recent coverage of a microwave radio receiver made from diamond?

Via Southgate ARC.

17 thoughts on “Get On 10 GHz For 3 Euros

  1. “Of course, the signals are extremely weak. But we are talking about a 15 mW transmitter 10 369 GHz over a distance of 18 km.”
    Well that’s incredible.

    Also, apparently a slice of spacecake has the same attenuation as a Spanish dictionary. These guys have priorities.

    1. The succes of this HB100 device depends on antenna height’s. 18 km distance was made with a 50 cm offset dish at 18 meter above ground level as receive station. The TX antenna (18dB horn) was at about 9 m agl. We made 32 km with the same receiver setup, but the transmitter at top of a 24m high building…

      1. I have a vintage Gunnplexer to, but it is less frequency stable in relation to a HB100. Two things are Important when operating a HB100. 1) Try to mount the PCB friction free. Little mechanical stress at the PCB lets the frequency drift. 2)Temperature isolate the box to let wind, sun and rain has less as possible influence at the device. Succes ;-)

          1. Actually I did use that phenomenon by talking directly into the dish ;-) The RX station (PD0SBS) was able to hear my voice due the vibration of my voice at the HB100 PCB in the focus of a dish. I did also a experiment by placing a HB100 at top of a HifI speaker. The speaker audio did modulate the HB100 in FM due vibrations. That is why you have to install that HB100 PCB stress free in a box, or whatever you like to mount it in, to make the frequency as stable as possible.

    1. Licensed Hamradio operators are allowed to operate the 3 cm band between 10.000 GHz and 10.500 GHz. In that band are ATV stations and repeaters active. Also beacons, smallband voice DX, digimodes and Moonbouncing. At least in Europe…

  2. Yesterday (11 January 2017) we did a open field experiment in ATV (amateur radio TV) with a HB100 device. Take a look here if you like to see a overview of the setup under terrible bad weather conditions (8bf storm). Just a HB100 with modified SMA connector output, connected at a penny-feed in a 40 cm dish.

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