Oh oh...

This page requires JavaScipt to be enabled in order to be able to view it...


First U.S. QSO on >400GHz


Hi all-

I'd like to report what I believe to be a first for QSOs above 400GHz here in the US. (DB6NT was first on the "band" at 411GHz with a 50 meter QSO)

On Nov 11, 2003 at 02:15z WA1ZMS/4 worked W4WWQ/4 on a frequency of 403GHz over a distance of 0.521km.

The details of the QSO are:
W4WWQ/4 was located at: 37-21-14.1 79-10-13.6
WA1ZMS/4 was located at: 37-21-23.6 79-10-31.1

The weather at the time of the QSO was:
Temp: 3.9C
Dew Point: 1.1C
Relative Humidity: 82%
Station pressure: 1006mb

The weather conditions result in a total atmospheric loss of 14.4dB per km!

Gear used for the QSO was the same basic gear used for our 241GHz QSOs last year but this time with new 30cm parabolic dishes. The feeds used on the parabolas are W2IMU horns designed for 241GHz, so the feed is over-moding and thus not optimal on 403GHz. When colder and dryer winter WX arrives, we have hopes of trying to break the 1km distance barrier.

Although any QSO above 300GHz is considered the same "band" by some, I would think that a QSO in the 400GHz range would be of interest to several people active on microwaves and just wanted to report it.

Brian, WA1ZMS/4

403GHz Pictures

Brian, WA1ZMS, poses for photo with 30cm dish over his shoulder.

Pete, W4WWQ, enjoys the warmth of the driver's seat while operating on 403GHz.

One of the 241/322/403GHz stations in the shack prior to making the 403GHz QSO. A specific harmonic of the 80GHz phase-locked Gunn oscillator in the station is exploited for a given "band" of operation.

Brian, WA1ZMS bangs out CW with a straight key for 403GHz QSO. Icom R-7000 IF receiver can be seen in rear of van.

Close-up view of cassegrain feed system showing W2IMU style horn and hyperbolic sub-reflector.

403GHz QSO Audio

You can listen to a an excerpt from the 0.5km 403GHz QSO (the file is a 16 second 350kB .WAV file).


For more pictures and information you can also look at

the page with the original 241 and 322GHz records
the follow on 241GHz distance record