It was an eyeball clubbed with a antenna workshop. We began with a discussion on Radio wave, Radio Frequency, Wave length, Resonation & Resonant frequencies. While explaining resonant frequencies VU2ASH/ Ashok Joshi used the example of resonation of sound in a dome. He then went on to speak about Velocity factor and velocity factor of transmission lines.
The discussion then moved to Radiating elements of an antenna, Lobe formation of the radiated signals & Ground factor. Ashok spoke about 3dB bandwidth and cut-off frequency of an antenna. Evolution of antennas right from basic half wave dipoles to full length quad antennas were discussed. He explained why a Dipole works best when hoisted at least lambda by 4 from the ground. Ashok then went on to explain about Termination of an antenna & its resonation, about feed point impedance and the need for Matching networks & baluns. While discussing impedance, Ashok used the example of Dipoles that have a 75 ohms impedance and how when the ends are brought down to 120 degrees to form an Inverted V the antenna impedance drops down to 50 ohms and elaborated on how the impedance of the antenna changes according to its shape.
There were various types of 2m home-brewed antennas that were on display which included a ground plain antenna, a vertical dipole, 3 element tape yagi, a aluminium 3 element yagi antenna with a matching unit, a 3 element quad & a TV ribbon cable slim jim antenna.
We first tuned the yagi made out of measuring tape with the help of a antenna analyser. We stopped briefly for a working lunch that included McDonald’s veg burgers, french fries, lots of Coke some Ice cream with chocolate topping, Kiwi fruit pastry.
After lunch till late evening we went on to construct and test 3 new ground plain antennas. In all a very fruitful exercise.
Here are some pics of the event:
Some of the comments from those who attended the workshop:
[02/08 21:34] Mohan Paralkar VU2MMJ: Dear PHARS team today was an excellent session n practical workshop for the members special thanks Ashokji n Udayaji for guidance for us..
[02/08 22:09] Vinayak Mali – Swl/ Pune Fire Brigade: Today I enjoyed the sessions and took actual effort for ham
[02/08 23:00] Udaya Patil VU2UPQ : The workshop was excellent. It was very energising to see the enthusiasm & participation of each one who attended the workshop.
It was a learning process for each one of us.
Many Thanks to Swati, Monica, Vinayak, Devendar, Amogh, Mohan, Sailesh, Kushal for participating & to you ASHOK / VU2ASH for your guidance support & participation & for the input session.
[02/08 23:15] Swati Patil SWL: Todays meeting was assume. Lots of things shared with us by VU2ASH & VU2UPQ. Thanks to all who attended the workshop & for all the snacks & goodies
[02/08 23:16] Ashok Joshi VU2ASH Thanks everyone . your eagerness and enthusiasm to do something was exceptional.
I enjoyed every bit of it, and what a marathon meeting/ workshop it was — 12 hours !!! Oh my