Log Periodic Antenna (2)

Part 2 (2011)

The objective actually was to have Channel 5 watchable since I am quite certain that Channel 2 and Channel 7 would still be clear even if I screw up with the antenna construction. I believe they have stronger transmission power compared to the other channels and besides, we still have the relayed channels which is very near (about 20-30 kms.) Unfortunately though, the towers are in the opposite direction ( south )


Continued in 2012

Today is May 21, 2012 and I can't remember when I wrote the above paragraph. Obviously, it has been a long time. In the spirit of trying to finish all unfinished posts, I'm gonna write the continuation today without pictures. Later on, I'm planning to review everything.

After several typhoons, the antenna is in a very bad state. Instead of being parallel to the ground, the front points downward. The channels from Manila are all gone suggesting a disconnect somewhere. We can only watch the relayed channels but even if the transmissions tower are nearer, the reception is still not good.

May 20, 2012, I got up early to fix the antenna. It is better to do this in the morning while it is not too hot. Rainy weather is coming and there's rain usually in the the afternoon.

I used magnet wire to connect the element for the simple reason that is quite easy to route. I know then that it was not proper way because I read somewhere that the thickness of the wire used as link affects the overall gain. The magnet wire was replaced with steel cable.

While removing the outer cover of the coaxial cable, I noticed that the insulator broke. About 0.25cm of plastic has separated itself from the rest. It seems like the insulator became brittle over time. I proceeded anyway and connected the cable to the antenna.

I pointed it North (Manila). Now the antenna is back in business with very clear receptions for stronger channels 2 and 7. Channels 4, 9, 11 are watchable although a bit noisy. There were also some UHF channels. But channel 5 which is why started this project is still a letdown with streaks that seem to flow from top to bottom. I wonder if it is caused by a mismatch or simply because the signal is just too weak.

Unable to fix the problem using the TVs fine tuning, I tried to find the optimum direction to point the antenna's front end. I used the coconut tree as the reference but I guess the tolerance is wide. The problem didn't go away. I was now beginning to suspect that something is amiss with the cable..

Fortunately, I have a spare coaxial cable. It is bit shorter compared to the one that is currently installed After making the connections, it is now confirmed that the old cable must be replaced. Channel 5 streaks are now gone and although there is some noise present in the picture which appears as white dots, this is way better and doesn't hurt the eyes as much.