A thirty-six element array antenna system

Thirty-six element square array, with mutual coupling between crossed slots for array elements, is used as an electronically scanned tracking antenna. The system does not require the movement of the antenna or the presence of an operator

Evaluation of data obtained from a 35 GHz propagation experiment Technical report no. 7

Effect of atmospheric humidity, pressure, and temperature on electromagnetic wave propagatio

Improved VHF direction finding system

Direction finding device operating at very high frequencies requires a loop antenna, mechanical rotation, and large structures. The system is applicable to an unmanned configuration. Direction information is extracted in the form of a direction cosine analog

Analysis and optimization of an omnidirectional direction-finding system

System determines the direction of arrival of an electromagnetic wave with the direction information in a readily usable form. It presents a relatively small physical structure and does not require mechanical positioning

Surveying the SO(10) Model Landscape: The Left-Right Symmetric Case

Grand Unified Theories (GUTs) are a very well motivated extensions of the Standard Model (SM), but the landscape of models and possibilities is overwhelming, and different patterns can lead to rather distinct phenomenologies. In this work we present a way to automatise the model building process, by considering a top to bottom approach that constructs viable and sensible theories from a small and controllable set of inputs at the high scale. By providing a GUT scale symmetry group and the field content, possible symmetry breaking paths are generated and checked for consistency, ensuring anomaly cancellation, SM embedding and gauge coupling unification. We emphasise the usefulness of this approach for the particular case of a non-supersymmetric SO(10) model with an intermediate left-right symmetry and we analyse how low-energy observables such as proton decay and lepton flavour violation might affect the generated model landscape.Comment: 36 pages, 6 figure

A study of antenna and radio frequency tracking system Final summary report, 1 Feb. 1963 - 30 Nov. 1965

Phase stability of very low frequency radio signal propagation, electronically scanned tracking antenna array, and inverted rf tracking syste

Transport and Dissipation in Quantum Pumps

This paper is about adiabatic transport in quantum pumps. The notion of ``energy shift'', a self-adjoint operator dual to the Wigner time delay, plays a role in our approach: It determines the current, the dissipation, the noise and the entropy currents in quantum pumps. We discuss the geometric and topological content of adiabatic transport and show that the mechanism of Thouless and Niu for quantized transport via Chern numbers cannot be realized in quantum pumps where Chern numbers necessarily vanish.Comment: 31 pages, 10 figure

The Hawking-Penrose singularity theorem for C1,1C^{1,1}-Lorentzian metrics

We show that the Hawking--Penrose singularity theorem, and the generalisation of this theorem due to Galloway and Senovilla, continue to hold for Lorentzian metrics that are of $C^{1, 1}$-regularity. We formulate appropriate weak versions of the strong energy condition and genericity condition for $C^{1,1}$-metrics, and of $C^0$-trapped submanifolds. By regularisation, we show that, under these weak conditions, causal geodesics necessarily become non-maximising. This requires a detailed analysis of the matrix Riccati equation for the approximating metrics, which may be of independent interest.Comment: Minor amendments in v4: Removed non-equivalent condition from Def. 2.2 and adapted Lemma 3.5 and the proof of Lemma 3.

Parametric resonance and spin-charge separation in 1D fermionic systems

We show that the periodic modulation of the Hamiltonian parameters for 1D correlated fermionic systems can be used to parametrically amplify their bosonic collective modes. Treating the problem within the Luttinger liquid picture, we show how charge and spin density waves with different momenta are simultaneously amplified. We discuss the implementation of our predictions for cold atoms in 1D modulated optical lattices, showing that the fermionic momentum distribution directly provides a clear signature of spin-charge separation.Comment: 6 pages, 3 figures, published versio