How is SND different to NF?

Signal to Noise Degradation, SND is a measure the extent of how the off-air or ultimate S/N ratio is degraded by a receive system. We can calculate where: Tsys is the equivalent system noise temperature at the space interface; and Tamb is the equivalent ambient noise temperature at the space interface. For more explanation of … Continue reading How is SND different to NF?

Receive only antenna for 160m – maximum receiver NF for SND

This article explores the design / analysis of a passive receive system for the 160m band, determining the maximum receiver noise figure (NF) to achieve a specified maximum S/N degradation (SND) by receiver internal noise. For explanation of the metric Signal to Noise Degradation (SND), see Signal to noise degradation (SND) concept. The antenna data … Continue reading Receive only antenna for 160m – maximum receiver NF for SND

Loop in ground (LiG) for rx only on low HF – #10 SND comparison with LoG

The Loop in Ground project is about a receive only antenna for low HF, but usable from MF to HF. The objective is an antenna of that is small, low profile, and can be located outside the zone where evanescent modes dominate around noise current carrying conductors, like house wiring to minimise noise pickup. To … Continue reading Loop in ground (LiG) for rx only on low HF – #10 SND comparison with LoG

Loop in ground (LiG) – #6 signal to noise degradation (SND)

Feasibility study – loop in ground for rx only on low HF laid out an initial design concept. This article sets out expected signal / noise degradation in a typical installation. 3.5MHz Let’s take ambient noise as Rural precinct in ITU-P.372-14. An NEC-5.0 model of the 3m a side LiG gives average gain -37.18dBi. An … Continue reading Loop in ground (LiG) – #6 signal to noise degradation (SND)

SND implications of variations on the untuned small loop at MF/lowHF

Three recent articles developed an explanation of the YouLoop-2T at MF/lowHF: Small untuned loop for receiving – simple model with transformer ; A transmission line 1:4 impedance transformer ; and Towards understanding the YouLoop-2T at MF/lowHF . The first and third articles explained the concept of signal/noise degradation (SND) statistic, and gave graphs of the … Continue reading SND implications of variations on the untuned small loop at MF/lowHF

Receive only antenna for 160m – K9AY matching and performance discussion

This article explores the design / analysis of a passive receive only antenna, a K9AY loop, for the 160m band (1.8MHz). The example and calculations assume linear systems, if there is significant nonlinearity that gives rise to significant IMD, IMD noise is not captured by the analysis. Results are for the scenarios calculated and may … Continue reading Receive only antenna for 160m – K9AY matching and performance discussion

Receive only antenna for 160m – matching and performance discussion

This article explores the design / analysis of a passive receive only antenna for the 160m band (1.8MHz). The example and calculations assume linear systems, if there is significant nonlinearity that gives rise to significant IMD, IMD noise is not captured by the analysis. Results are for the scenarios calculated and may not be extensible … Continue reading Receive only antenna for 160m – matching and performance discussion

The need for infinite preamplifier gain?

A recent posting on social media kicked off some discussion about infinite gain preamplifiers, mostly in the context of an unloaded very short vertical. Over the past couple of years I’ve had a number of comments and questions about active antennas, instigated by my ARRL book, Receiving Antennas for the Radio Amateur. The “main ingredient” … Continue reading The need for infinite preamplifier gain?