Log Periodic Antenna (1)

The antenna motivation

Who needs an antenna when there's cable TV available?  What is log periodic and why log periodic?

I live about 90 kilometers from the capital Manila and TV signals are weak.  We have two local relayed channels of the biggest TV networks, GMA7 and ABS-CBN2 broadcast on channels 12 and 10, respectively.  A simple dipole is enough to watch these two channels and that was our setup since moving here.  But then there is an emerging power in the Philippine TV network wars and it is Channel 5.  I believe the guys behind this channel is quite aggressive in designing their programming and it is also refreshing to watch an alternative.  I like channel 5 and the kids like it too which is enough reason for me to construct an antenna with a better reception.  To answer the first question, I don't think we need cable TV.  Some news and a little of those documentaries is enough for me.  The kids are happy with Ben 10, Sponge Bob, etc.  Why pay when all of these are available and free?

The log periodic antenna

So what is a log periodic antenna?  The complete name for this type of antenna is Log Periodic Dipole Antenna (LPDA) TV channels are in the so-called VHF and UHF segment of the RF spectrum and each channel has its own transmission frequency.   A dipole antenna can be optimized to receive one channel if cut according to a known formula but it won't be able to give you a good reception when you change the channel.   Since it is quite impractical to cut a dipole for each channel, a log periodic antenna is a good option.  Log periodic are wideband antennas and thus capable of receiving multiple channels.

Why part 2

Since long posts are somewhat boring,  I'll be posting another installment on the same subject.