Today John m3eqq and Rebecca and myself M0hfh put the club antenna 10m in the air slung between two trees on nylon rope. We are using an 80m rectangular loop this year courtesy of Garry g7nvz having ratios of L1 (30m) to L2 (10m) total length one wavelength (80m) which has a theoretical gain of 4db compared to a dipole. We will be using the Yaesu 450d with the club manual ATU; Generators should give the full 100w output.
The Field Day site is at GL13 9TH hook street, field located behind Hook House 51°41’44.0″N 2°28’16.7″W
John Rowden M0hfh (@johnrowden59) tweeted at 10:28 am on Thu, Aug 12, 2021: Well done Peter, we always knew you were clever, and that was before your degree, keep going we will be proud to have Dr. Peter Barnes in Tsgarc. Best wishes from all at club in Thornbury. (https://twitter.com/johnrowden59/status/1425751055682478084?s=03)
Well perhaps the way we calculate and the calculators and computers we use to get the answer. Our test equipment and radio’s have also taken a great leap forward; I have smiths charts on my analyser these days where it used to be complicated and time consuming to get the resolution to complex number problems.
The link below takes you to Frank Jones antenna handbook
I like to try some of the old designs and compare the performance with some of the improved antenna designs we have today,( Roll on Field day 2021) but mostly its the detail of the design description that leads to ideas for improvements.
It seemed sensible to test the antenna matching before attaching it to a kite however the half wave for 80m was too long to put up at my QTH so i swapped it out for a half wave on 40m and attached it to the matching unit; using a mini VNA and MFJ 259B i set about matching the radiator. The starting point indicated resonance at 6.6mhz so trimming the length i slowly brought it to resonance at 7.04mhz with vswr of 1: 1.2. To achieve this i had to attach a counterpoise of 3m, my only criticism being there was no attachment point for a counterpoise.
The screen shot shows the WSPR test at 200mw from my QTH on the 09/08/2020.
A CW QSO into Kazakhstan at 50 watts was also achieved, it seems to work well.
Great antenna IP65 rating with good mounting clamp setup will report back when i test the full 80m half wave antenna supplied with the unit at field day.
The fox hunt on Wednesday evening turned into a damp affair and was attended by Mike g0jmd, Paul m0znb , Garry g7nvz and John m0hfh. Peter Barnes m0swn was the fox who had gone to ground in the Mundy Playing fields accompanied by Brittany M6LVB. First hound to see the fox was John m0hfh using body shielding and a hand held, second was Garry g7nvz and Paul m0znb bringing up the rear. We had a cream cup cakes as our prize and returned to rock street around 9.15, a fun evening.
Weather is not great for this event however the Mundy playing fields has a car park. The 5 watt Transmitter will be operating from 19.00 hrs this evening, 3.568mhz CW and can be received in Alveston at 599 so try your receivers on the way over and report the distances. The second transmitter will be <1 watt @ 3.579.3 Mhz cw and will be at the Mundy playing fields in Thornbury;decode the Identifiers for both signals and report your findings via qrz or the website or to John m0hfh.
Both transmitters send the club callsign initially G4ABC , with a short message for just over a minute which is repeated at approximately 30 second intervals.