Antenna Handbook 1937

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Has anything changed in the maths since 1937?

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

http://www.tubebooks.org/Books/Jonesant.pdf

Still valid today? – leave a reply 

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. 

John (m0hfh)

Covid Changes

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Due to recent changes in the Covid regulations the transition back to physical meetings is now cancelled.

The club will still have it’s weekly VHF net on Friday evenings at 20:00 local time.

The other informal nets that groups of members have and the members Zoom meetings will be how we keeping in contact.

 

Return to physical club meetings

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We are planning to restart club meetings at the Chantry. Initially we are considering a fortnightly meeting on the usual Wednesday (1st and 3rd). The first meeting back is now planned for the 16th September. The first meeting will be purely a social meeting. Please let the Secretary know whether you plan to attend, this will allow us to estimate whether it is financially viable to run meetings presently. The 2nd, 4th and 5th Wednesday of each month will continue to be a Zoom meeting for members.

The following Terms and Conditions shall be adhered to;

  1. No attendance at club if you are showing any signs of COVID-19 or have been told to isolate for any other reason.
  2. All members are to perform their own personal risk assessment as to whether they should or should not attend. This should be at a level such that the individual member feels safe. Guidance if required please contact either the Secretary, Vice Chairman or Treasurer.
  3. Tables and other surfaces to be sanitised before club starts at 7:30pm. The room will be ventilated by all means possible i.e. doors and windows open.
  4. No attendance before 7:30pm. This will allow for two members to setup and sanitise the room from 7:00pm.
  5. Masks to be worn at all times.
  6. No Tea and Coffee facilities will be available. Members can bring their own ready made beverage in a suitable container.
  7. No change will be given for Subs or Membership fees, any balance will be added to your account. Please Pre-pay if possible.
  8. All members shall use hand sanitiser upon entry or re-entry to the room, which will be provided by the Chantry at the entry to the Buckingham room.
  9. Only one member in the shack at any time and only one member to use the shack radio equipment per week.
  10. Please respect social distancing when using the other facilities within the building/s (e.g. Toilets and Halls).

The above will be regularly re-assessed and either added to or amended as required by the committee. 

All members who have not yet paid their yearly membership fee will be required to do so before the end of October.

Garry G7NVZ Vice-Chairman on behalf of the committee.

Uk Antennas End fed half wave

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Thinking about a suitable antenna for use with a kite i decided to purchase UK antennas multi band end fed.

end-fed-antenna-with-mounting-bracket-80-40-20-17-15-12-10m

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.

Conclusion
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.

John m0hfh

COVID-19

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The Thornbury and South Gloucestershire Amateur Radio Club (TSGARC) has today taken the decision to postpone all future Wednesday evening meetings during the current Corona Virus outbreak.

This decision has been taken to safeguard the health of all members and to comply with the general ‘Delay’ tactic being employed currently. It is currently proposed that this course of action is taken for a period of three months however it will be reviewed regularly and shortened/extended as required.

The forthcoming Annual General Meeting will be postponed until a date in October. Yearly subscriptions will still be collected inline with the current constitution, however yearly subscriptions will only be considered overdue 1 month after weekly meetings re-commence. Should you wish to pay your subscription by bank transfer please email the Treasurer to this effect.

In the meantime…. The current Friday net at 8pm will also be added to with a Wednesday Zoom meeting commencing at 8pm local time. Details for the Zoom meeting will be sent to members by email. The Friday Net will start on 145.500MHz and typically move to 145.450MHz.

The committee wishes every member well at this time.

Paul M0ZMB

Co-opted Ordinary Member

Changes to the programme.

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Due to external influences we are unable to meet at the Chantry on the 6th May 2020.

The talk / Q&A from Andy Jenner (G7KNA) our RSGB representative will now be held on 13th May 2020.

On the 6th May we will probably be out and about, details to follow.