Analysis of 2 Styles of Homebrew Antennas

Electromagnetic theory basics Classic Dipole Analysis

How big should our antennas be? frequency range 2.45GHz Lambda * frequency = speed of light –Lambda = (3e8m/s)/(2.45e9s^-1) Lambdba = 0.122m or 4.8in

The “Cantenna” The first type of antenna and very common in the Homebrew world is the can-based antenna or cantenna. Fabrication Parts –Can –Piece of standard 50ohm wire –N-type connector

Fabrication leads to:

So what does a cantenna radiation beam look like?

Printed Dipole Array This uses antenna strip idea as opposed to hollow conductive waveguides to do its work. Fabrication –Glass substrate –Adhesive copper roll –Vinyl cutter

Fabrication leads to

Recognizing the dipole array multiple dipoles squeezing beam and increasing gain

Dipole Array E&M field patterns

Why the tapered feed line (balun)? Balance/unbalance transmission line for VSWR characteristics

The Printed Dipole Array Antenna beam?

Which is the better antenna? VS.

Top of vassar parking structure Field Testing Duplicate parameters of cantenna test found online and compare results –1320ft Line of Sight distance –Standard dipole on AP/Source/tx –Laptop using plug-in card for destination/rcvr 1320 ft Access Point/source Laptop w/card Roof of my home

Cantenna test results mhttp://home.carolina.rr.com/harothberg/Test2.ht m Control: only using pc and wireless card –Signal Level: -89dBm -> 1.26e-12W Actual test: using can design –Signal Level: -68dBm -> 1.58e-10W dBi = log[base 10](P1/P2) –2.1dBi when compared to power from card

Printed Dipole Array Test Setup Views from Source/AP and Destination/Laptop 1320 ft: AP on home roof 1320 ft: laptop site on Vassar parking

Printed Dipole Array Test Results Control: only using pc and wireless card –Signal Strength Level: -91dB Actual test: using printed dipole array design –Signal Strength Level: -65dB dBi = log[base 10](P1/P2) –2.6dBi when compared to power from card Wireless Card Printed Dipole Array

Test Results Findings Absolutes [Cantenna vs. P.D.] Antenna Strength: 2.1dBi vs. 2.6dBi Surprise results of holding P.D antenna with and without one’s hand: –An unintended experiment happened as the antenna was being tested. One test run involved me holding the antenna with my hand (accidentally), while the other involved me holding the antenna in a nonconducting paper bag. Antenna gain showed a relative increase of +9dB in the signal when no hands were used to hold the antenna. That is a 3 time doubling of power in the signal. These results simply stress the significant affect biological contact can have on performance and points to better ways of insulating the printed dipole antenna from conductive influences.

The better antenna, based on analysis: Gain/power and coverage –P.D.: 3 dipoles focused in 1D great gain and coverage, good for community setting –Can: has 1 dipole that is focused in 2D okay on gain, low on coverage, good for point to point Fabrication –P.D.: mass production easier –Can: one-off production easier Portability –P.D.: low profile(2D), lightweight, durable –Can: bulky(3D), lightweight, durable