This is not a portfolio. It is a working log — experiments in progress, results that didn't go as expected, and observations worth writing down. Finished builds with full documentation live on the Projects page. Everything else lives here.
Ran a 60 ft wire end-fed as a long-wire antenna for the SDR, targeting FM broadcast reception. No matching network. Out of the gate it produced nothing usable — the impedance mismatch between an unmatched end-fed wire and the SDR's 50 Ω input is severe enough to kill sensitivity before the signal ever reaches the receiver.
Added a 20 ft counterpoise to give the RF a return path. Reception improved marginally but remained poor — scratchy, difficult to follow, marginal SNR. Both the wire and the counterpoise were laid on the floor of the house at the time of testing, which compounds the problem: a wire antenna that close to the ground loses effective height, picks up conducted noise from the building, and has its radiation pattern severely distorted.
Built a 3-element Yagi from PVC tubing with 26 AWG copper wire elements, designed for the GMRS band (462–467 MHz). Driven element is a half-wave split dipole. Director and reflector are sized around the driven per standard Yagi geometry — reflector longer, director shorter.
Getting to a working SWR required significantly more shortening of the driven element than the initial calculations called for. The element kept coming in high; repeated trimming brought it down to an SWR of 1.5 across the target band, which is acceptable. The director was also shortened beyond nominal — left at calculated length it was reflecting rather than directing, so it was trimmed until that behavior stopped. The reflector was left at the calculated length and not adjusted.
Field test was conducted at approximately 4 miles with a Radioddity GM30 Plus on each end — one mobile, one stationary indoors. At that range with battery running low on the mobile unit, there was a marginal but noticeable improvement when the antenna was oriented toward the other station versus off-axis. In an urban environment at 4 miles, multipath and obstructions make directionality difficult to isolate cleanly — the result was suggestive but not conclusive.
Crystal-style passive AM receiver built on a breadboard. Hand-wound PVC coil inductor, fixed ceramic capacitor, Schottky diode detector, piezoelectric earphone output. No power source — driven entirely by intercepted signal energy. Antenna was an aluminum ladder. Target station KTAR 620 kHz was received and demodulated.
Two significant findings came out of this build: grounding the circuit degraded reception rather than improving it, and the low-Q tank had insufficient selectivity to reject KTAR's 5,000 W signal regardless of how the LC values were adjusted. The receiver was sensitive but not selective — those two findings directly contradict each other and are both documented.